{"version":"1.0.0","segments":[{"startTime":0.401,"endTime":2.484,"body":"(whoosh)"},{"startTime":4.98,"endTime":7.8,"body":"- So I'm Myles Allen, the"},{"startTime":4.98,"endTime":7.8,"body":"Frank Jackson Professor"},{"startTime":7.8,"endTime":9.93,"body":"of the Environment at Gresham College,"},{"startTime":9.93,"endTime":13.11,"body":"and today we're talking"},{"startTime":9.93,"endTime":13.11,"body":"about the carbon cycle"},{"startTime":13.11,"endTime":14.07,"body":"behind net zero."},{"startTime":14.07,"endTime":19.05,"body":"So understanding where the"},{"startTime":14.07,"endTime":19.05,"body":"carbon dioxide that is causing"},{"startTime":19.05,"endTime":22.41,"body":"the problem that we've been"},{"startTime":19.05,"endTime":22.41,"body":"talking about in the previous"},{"startTime":22.41,"endTime":25.86,"body":"three lectures, where it all comes from,"},{"startTime":25.86,"endTime":28.23,"body":"where eventually it will go,"},{"startTime":28.23,"endTime":31.32,"body":"and what is going to happen next."},{"startTime":31.32,"endTime":34.8,"body":"So you'll notice, we've got"},{"startTime":31.32,"endTime":34.8,"body":"a new toy with us today,"},{"startTime":34.8,"endTime":37.65,"body":"which is its first starting,"},{"startTime":34.8,"endTime":37.65,"body":"so we hope it's going to work."},{"startTime":37.65,"endTime":40.65,"body":"But I'm going to start off"},{"startTime":37.65,"endTime":40.65,"body":"talking about this curve."},{"startTime":40.65,"endTime":44.16,"body":"It's high time in any series"},{"startTime":40.65,"endTime":44.16,"body":"of lectures on climate"},{"startTime":44.16,"endTime":46.28,"body":"and climate change, we have to look at,"},{"startTime":46.28,"endTime":48.57,"body":"at some point at the Keeling Curve."},{"startTime":48.57,"endTime":52.77,"body":"Charles David Keeling started measuring,"},{"startTime":52.77,"endTime":55.11,"body":"back in the late 1950s,"},{"startTime":55.11,"endTime":58.71,"body":"he started measuring the"},{"startTime":55.11,"endTime":58.71,"body":"concentration of carbon dioxide"},{"startTime":58.71,"endTime":61.23,"body":"in the atmosphere on Mauna Loa in Hawaii,"},{"startTime":61.23,"endTime":64.953,"body":"sort of well away from any"},{"startTime":61.23,"endTime":64.953,"body":"local sources of pollution."},{"startTime":65.79,"endTime":68.61,"body":"And he noticed immediately"},{"startTime":65.79,"endTime":68.61,"body":"that it was going up."},{"startTime":68.61,"endTime":71.46,"body":"So the first thing you notice"},{"startTime":68.61,"endTime":71.46,"body":"about this curve is clearly"},{"startTime":71.46,"endTime":72.93,"body":"that it's going up."},{"startTime":72.93,"endTime":74.76,"body":"The second thing you probably notice,"},{"startTime":74.76,"endTime":76.53,"body":"regardless of where you are in the room,"},{"startTime":76.53,"endTime":79.17,"body":"is that it's curving upwards."},{"startTime":79.17,"endTime":82.5,"body":"As our rates of emissions"},{"startTime":79.17,"endTime":82.5,"body":"have been going up"},{"startTime":82.5,"endTime":83.85,"body":"throughout this period,"},{"startTime":83.85,"endTime":87.48,"body":"the rate at which carbon"},{"startTime":83.85,"endTime":87.48,"body":"dioxide has been accumulating in"},{"startTime":87.48,"endTime":90.75,"body":"the atmosphere is also going up."},{"startTime":90.75,"endTime":92.52,"body":"And the third thing you notice, perhaps,"},{"startTime":92.52,"endTime":95.64,"body":"is this sort of zigzag,"},{"startTime":92.52,"endTime":95.64,"body":"which is part of this,"},{"startTime":95.64,"endTime":99.18,"body":"which is every year, carbon"},{"startTime":95.64,"endTime":99.18,"body":"dioxide goes up rapidly"},{"startTime":99.18,"endTime":100.74,"body":"and then goes down again and up again."},{"startTime":100.74,"endTime":103.92,"body":"And each year it goes"},{"startTime":100.74,"endTime":103.92,"body":"up a little bit further."},{"startTime":103.92,"endTime":107.88,"body":"And in fact, the size of"},{"startTime":103.92,"endTime":107.88,"body":"this zigzag is comparable"},{"startTime":107.88,"endTime":112.263,"body":"to about five years or"},{"startTime":107.88,"endTime":112.263,"body":"so of the overall trend."},{"startTime":113.19,"endTime":115.38,"body":"And this is the first hint you get"},{"startTime":115.38,"endTime":118.383,"body":"that putting carbon"},{"startTime":115.38,"endTime":118.383,"body":"dioxide in the atmosphere,"},{"startTime":119.31,"endTime":120.75,"body":"it's not like any other pollutant."},{"startTime":120.75,"endTime":123.0,"body":"Well, it's not like most pollutants,"},{"startTime":123.0,"endTime":125.73,"body":"which just come from human activity."},{"startTime":125.73,"endTime":128.13,"body":"When we're putting carbon"},{"startTime":125.73,"endTime":128.13,"body":"dioxide in the atmosphere,"},{"startTime":128.13,"endTime":132.103,"body":"we're adding something to"},{"startTime":128.13,"endTime":132.103,"body":"what's already complicated,"},{"startTime":133.65,"endTime":136.692,"body":"but also very predictable"},{"startTime":133.65,"endTime":136.692,"body":"because these wiggles"},{"startTime":136.692,"endTime":141.003,"body":"are much the same size every"},{"startTime":136.692,"endTime":141.003,"body":"year, natural carbon cycle."},{"startTime":142.23,"endTime":147.23,"body":"And if we look at this"},{"startTime":142.23,"endTime":147.23,"body":"animation from produced by NASA"},{"startTime":147.84,"endTime":151.59,"body":"of carbon dioxide in the course of a year,"},{"startTime":151.59,"endTime":154.5,"body":"transparent air is the"},{"startTime":151.59,"endTime":154.5,"body":"concentrations at the beginning"},{"startTime":154.5,"endTime":155.333,"body":"of the year."},{"startTime":155.333,"endTime":158.16,"body":"And notice how we see this"},{"startTime":155.333,"endTime":158.16,"body":"pulsing of carbon dioxide"},{"startTime":158.16,"endTime":160.35,"body":"coming out of the tropical rainforests."},{"startTime":160.35,"endTime":162.3,"body":"You're probably used to"},{"startTime":160.35,"endTime":162.3,"body":"thinking of tropical rainforests"},{"startTime":162.3,"endTime":166.29,"body":"as the lungs of the planet"},{"startTime":162.3,"endTime":166.29,"body":"absorbing carbon dioxide."},{"startTime":166.29,"endTime":169.77,"body":"But they also, during the course of a day,"},{"startTime":169.77,"endTime":171.15,"body":"release a lot of carbon dioxide."},{"startTime":171.15,"endTime":173.43,"body":"That's why you're seeing this orange air"},{"startTime":173.43,"endTime":174.84,"body":"is high carbon dioxide air."},{"startTime":174.84,"endTime":176.64,"body":"Now look what's happening now, this is,"},{"startTime":176.64,"endTime":179.94,"body":"look at the time of year,"},{"startTime":176.64,"endTime":179.94,"body":"we've got to, it's November."},{"startTime":179.94,"endTime":183.33,"body":"So all the Northern Hemisphere"},{"startTime":179.94,"endTime":183.33,"body":"forests are dying off"},{"startTime":183.33,"endTime":186.99,"body":"and releasing loads of carbon"},{"startTime":183.33,"endTime":186.99,"body":"dioxide into the atmosphere."},{"startTime":186.99,"endTime":189.36,"body":"So average concentrations"},{"startTime":186.99,"endTime":189.36,"body":"in the atmosphere"},{"startTime":189.36,"endTime":192.39,"body":"are rushing upwards in the"},{"startTime":189.36,"endTime":192.39,"body":"space of a couple of months"},{"startTime":192.39,"endTime":196.14,"body":"by more than about five years"},{"startTime":192.39,"endTime":196.14,"body":"worth of human emissions."},{"startTime":196.14,"endTime":197.79,"body":"And you can see, it's accumulating"},{"startTime":197.79,"endTime":198.72,"body":"in the Northern Hemisphere."},{"startTime":198.72,"endTime":203.19,"body":"This orange is higher carbon dioxide air."},{"startTime":203.19,"endTime":205.77,"body":"This is sort of getting into February now."},{"startTime":205.77,"endTime":207.81,"body":"But watch carefully what happens now,"},{"startTime":207.81,"endTime":211.05,"body":"as surely as spring follows winter,"},{"startTime":211.05,"endTime":215.28,"body":"watch the Northern Hemisphere"},{"startTime":211.05,"endTime":215.28,"body":"carbon dioxide concentrations"},{"startTime":215.28,"endTime":217.053,"body":"as we come through April."},{"startTime":218.1,"endTime":222.81,"body":"And just as the, as you watch"},{"startTime":218.1,"endTime":222.81,"body":"carefully what's going on,"},{"startTime":222.81,"endTime":225.27,"body":"we come into May and all the plant life"},{"startTime":225.27,"endTime":228.45,"body":"in the Northern Hemisphere"},{"startTime":225.27,"endTime":228.45,"body":"starts to grow again."},{"startTime":228.45,"endTime":233.1,"body":"And suddenly, it mops up in"},{"startTime":228.45,"endTime":233.1,"body":"a very short space of time,"},{"startTime":233.1,"endTime":237.96,"body":"mops up very rapidly that"},{"startTime":233.1,"endTime":237.96,"body":"excess carbon dioxide"},{"startTime":237.96,"endTime":240.42,"body":"in the Northern Hemisphere"},{"startTime":237.96,"endTime":240.42,"body":"as the trees regrow"},{"startTime":240.42,"endTime":243.63,"body":"and reabsorb it into the biosphere,"},{"startTime":243.63,"endTime":246.0,"body":"the plant life of this planet."},{"startTime":246.0,"endTime":250.38,"body":"And then we're left come the"},{"startTime":246.0,"endTime":250.38,"body":"same time the following year"},{"startTime":250.38,"endTime":253.86,"body":"with just wisps of carbon"},{"startTime":250.38,"endTime":253.86,"body":"dioxide in the tropics."},{"startTime":253.86,"endTime":254.792,"body":"But of course, you will notice,"},{"startTime":254.792,"endTime":257.91,"body":"there's more orange there"},{"startTime":254.792,"endTime":257.91,"body":"than there was to start with."},{"startTime":257.91,"endTime":259.98,"body":"That's just one year."},{"startTime":259.98,"endTime":263.49,"body":"And that's the accumulation"},{"startTime":259.98,"endTime":263.49,"body":"from human emissions"},{"startTime":263.49,"endTime":266.52,"body":"during that, from emissions"},{"startTime":263.49,"endTime":266.52,"body":"due to human activity"},{"startTime":266.52,"endTime":269.25,"body":"just during that period."},{"startTime":269.25,"endTime":272.28,"body":"So you can see how there is"},{"startTime":269.25,"endTime":272.28,"body":"this natural carbon cycle"},{"startTime":272.28,"endTime":277.28,"body":"we have to understand in"},{"startTime":272.28,"endTime":277.28,"body":"order to understand what human"},{"startTime":277.65,"endTime":280.65,"body":"activities are doing to carbon"},{"startTime":277.65,"endTime":280.65,"body":"dioxide in the atmosphere."},{"startTime":280.65,"endTime":284.13,"body":"But it's also very predictable"},{"startTime":280.65,"endTime":284.13,"body":"because it's so tied"},{"startTime":284.13,"endTime":287.91,"body":"to the seasonal cycle to the"},{"startTime":284.13,"endTime":287.91,"body":"growth and decay of forests."},{"startTime":287.91,"endTime":289.56,"body":"But it's amazing."},{"startTime":289.56,"endTime":291.88,"body":"It's amazing the amount of carbon dioxide"},{"startTime":292.98,"endTime":295.74,"body":"that's passed every month"},{"startTime":295.74,"endTime":299.28,"body":"between the surface and the atmosphere."},{"startTime":299.28,"endTime":303.69,"body":"And this also raises some very"},{"startTime":299.28,"endTime":303.69,"body":"important practical questions"},{"startTime":303.69,"endTime":306.9,"body":"about how we deal with carbon"},{"startTime":303.69,"endTime":306.9,"body":"dioxide that we'll come to"},{"startTime":306.9,"endTime":308.64,"body":"later on in this lecture."},{"startTime":308.64,"endTime":311.82,"body":"Particularly relating"},{"startTime":308.64,"endTime":311.82,"body":"to trying to use trees"},{"startTime":311.82,"endTime":314.34,"body":"to absorb the carbon"},{"startTime":311.82,"endTime":314.34,"body":"dioxide that we're releasing"},{"startTime":314.34,"endTime":318.66,"body":"into the atmosphere when trees"},{"startTime":314.34,"endTime":318.66,"body":"are doing all this anyway."},{"startTime":318.66,"endTime":323.66,"body":"It makes it even more difficult"},{"startTime":318.66,"endTime":323.66,"body":"to manipulate the biosphere"},{"startTime":323.73,"endTime":328.14,"body":"to help us out with dealing"},{"startTime":323.73,"endTime":328.14,"body":"with what we're doing"},{"startTime":328.14,"endTime":331.683,"body":"to the rest of the climate"},{"startTime":328.14,"endTime":331.683,"body":"of the carbon-cycle system."},{"startTime":333.33,"endTime":335.97,"body":"Just to emphasize how predictable this is,"},{"startTime":335.97,"endTime":339.273,"body":"if we look back over the past,"},{"startTime":340.286,"endTime":343.68,"body":"so Charles David Keeling's observations"},{"startTime":343.68,"endTime":348.33,"body":"of the blue line here, which"},{"startTime":343.68,"endTime":348.33,"body":"was started in the 1950s."},{"startTime":348.33,"endTime":350.04,"body":"If we want to look back further than that,"},{"startTime":350.04,"endTime":353.13,"body":"we have to look at bubbles"},{"startTime":350.04,"endTime":353.13,"body":"trapped in ice cores"},{"startTime":353.13,"endTime":356.31,"body":"which preserve ancient air"},{"startTime":356.31,"endTime":357.99,"body":"and allow us to see the concentration"},{"startTime":357.99,"endTime":360.03,"body":"of carbon dioxide back over time."},{"startTime":360.03,"endTime":364.71,"body":"And if we go back to the"},{"startTime":360.03,"endTime":364.71,"body":"year zero, so 2000 years ago,"},{"startTime":364.71,"endTime":368.7,"body":"we can see that concentrations"},{"startTime":364.71,"endTime":368.7,"body":"were very constant."},{"startTime":368.7,"endTime":371.13,"body":"I'm not quite sure what happened here"},{"startTime":371.13,"endTime":375.54,"body":"and, but it may have been sort"},{"startTime":371.13,"endTime":375.54,"body":"of specific to Antarctica."},{"startTime":375.54,"endTime":378.33,"body":"So you can see that and"},{"startTime":375.54,"endTime":378.33,"body":"notice the sort of truncation"},{"startTime":378.33,"endTime":380.49,"body":"of time scales here."},{"startTime":380.49,"endTime":383.22,"body":"But you can see they were"},{"startTime":380.49,"endTime":383.22,"body":"very constant till we invented"},{"startTime":383.22,"endTime":386.55,"body":"the steam engine and started"},{"startTime":383.22,"endTime":386.55,"body":"burning coal in a serious way."},{"startTime":386.55,"endTime":389.55,"body":"And then immediately,"},{"startTime":386.55,"endTime":389.55,"body":"concentrations started going up."},{"startTime":389.55,"endTime":392.01,"body":"If you look even further back in time,"},{"startTime":392.01,"endTime":393.93,"body":"these are logarithmic scales."},{"startTime":393.93,"endTime":395.783,"body":"So as you move to the left on this,"},{"startTime":395.783,"endTime":400.08,"body":"you are really going back in"},{"startTime":395.783,"endTime":400.08,"body":"time scales as well as time."},{"startTime":400.08,"endTime":402.21,"body":"And you can see that it's really,"},{"startTime":402.21,"endTime":405.06,"body":"you have to go back to a"},{"startTime":402.21,"endTime":405.06,"body":"couple of million years"},{"startTime":405.06,"endTime":408.42,"body":"before you see carbon dioxide"},{"startTime":405.06,"endTime":408.42,"body":"concentrations as high"},{"startTime":408.42,"endTime":409.62,"body":"as they are now."},{"startTime":409.62,"endTime":412.86,"body":"And you'd have to go back"},{"startTime":409.62,"endTime":412.86,"body":"over 20 million years"},{"startTime":412.86,"endTime":414.66,"body":"to see carbon dioxide concentrations"},{"startTime":414.66,"endTime":416.55,"body":"as high as where they're going"},{"startTime":416.55,"endTime":419.538,"body":"if we carry on emitting"},{"startTime":416.55,"endTime":419.538,"body":"at the rate we're doing"},{"startTime":419.538,"endTime":421.593,"body":"over the course of this century."},{"startTime":423.18,"endTime":426.497,"body":"So that's what carbon dioxide has done."},{"startTime":426.497,"endTime":428.88,"body":"And you know, the obvious"},{"startTime":426.497,"endTime":428.88,"body":"next question is also why"},{"startTime":428.88,"endTime":431.52,"body":"is it going up so fast at the moment?"},{"startTime":431.52,"endTime":433.11,"body":"And for most people these days,"},{"startTime":433.11,"endTime":434.25,"body":"the answer's pretty obvious."},{"startTime":434.25,"endTime":437.52,"body":"But it's worth digressing"},{"startTime":434.25,"endTime":437.52,"body":"briefly on, you know,"},{"startTime":437.52,"endTime":440.97,"body":"how we're confident about"},{"startTime":437.52,"endTime":440.97,"body":"cause and effect here."},{"startTime":440.97,"endTime":443.88,"body":"Because there is a"},{"startTime":440.97,"endTime":443.88,"body":"persistent myth out there"},{"startTime":443.88,"endTime":447.005,"body":"that oh, scientists"},{"startTime":443.88,"endTime":447.005,"body":"don't really know whether"},{"startTime":447.005,"endTime":447.84,"body":"the carbon dioxide is going up"},{"startTime":447.84,"endTime":449.31,"body":"because of fossil fuel burning."},{"startTime":449.31,"endTime":452.88,"body":"It might be being released"},{"startTime":449.31,"endTime":452.88,"body":"by the oceans, for example."},{"startTime":452.88,"endTime":457.88,"body":"And the origin of this myth"},{"startTime":452.88,"endTime":457.88,"body":"is this relationship you see"},{"startTime":457.92,"endTime":462.92,"body":"between carbon dioxide"},{"startTime":457.92,"endTime":462.92,"body":"concentrations and temperature"},{"startTime":463.29,"endTime":466.32,"body":"over the past 800,000 years"},{"startTime":466.32,"endTime":470.04,"body":"through the cycle of the Ice Ages."},{"startTime":470.04,"endTime":473.79,"body":"And for a while, people thought"},{"startTime":473.79,"endTime":477.42,"body":"they could detect that carbon dioxide"},{"startTime":477.42,"endTime":480.48,"body":"was falling shortly after temperatures"},{"startTime":480.48,"endTime":483.18,"body":"started falling and rising shortly after"},{"startTime":483.18,"endTime":485.37,"body":"temperatures started rising."},{"startTime":485.37,"endTime":489.75,"body":"In fact, the modern assessment"},{"startTime":485.37,"endTime":489.75,"body":"is you can't really tell"},{"startTime":489.75,"endTime":492.21,"body":"which is leading which, there's not,"},{"startTime":492.21,"endTime":494.753,"body":"there's too much noise in the data."},{"startTime":494.753,"endTime":497.28,"body":"But this gave rise to the idea, oh,"},{"startTime":497.28,"endTime":499.217,"body":"it's temperature's driving carbon dioxide,"},{"startTime":499.217,"endTime":501.84,"body":"not the other way around."},{"startTime":501.84,"endTime":506.22,"body":"In fact, what's going on here"},{"startTime":501.84,"endTime":506.22,"body":"is that as temperatures rise,"},{"startTime":506.22,"endTime":507.21,"body":"the oceans warm,"},{"startTime":507.21,"endTime":511.328,"body":"they release carbon to the"},{"startTime":507.21,"endTime":511.328,"body":"atmosphere and that reinforces"},{"startTime":511.328,"endTime":512.91,"body":"the rising temperature."},{"startTime":512.91,"endTime":516.39,"body":"So it is a positive feedback happening,"},{"startTime":516.39,"endTime":519.93,"body":"but we wouldn't actually"},{"startTime":516.39,"endTime":519.93,"body":"expect on these time scales"},{"startTime":519.93,"endTime":523.251,"body":"to be able to detect any delay."},{"startTime":523.251,"endTime":526.11,"body":"What's going on at the moment, of course,"},{"startTime":526.11,"endTime":528.783,"body":"that's what's happened over the past,"},{"startTime":529.98,"endTime":531.93,"body":"that's where we are now and"},{"startTime":529.98,"endTime":531.93,"body":"that's what's happened over"},{"startTime":531.93,"endTime":533.25,"body":"the past century."},{"startTime":533.25,"endTime":535.62,"body":"That's a very, very different process."},{"startTime":535.62,"endTime":537.6,"body":"And we know it's a different process."},{"startTime":537.6,"endTime":541.8,"body":"We know it's being driven by"},{"startTime":537.6,"endTime":541.8,"body":"something entirely different."},{"startTime":541.8,"endTime":544.59,"body":"Thanks to the work"},{"startTime":541.8,"endTime":544.59,"body":"actually of Ralph Keeling,"},{"startTime":544.59,"endTime":547.98,"body":"who was actually, who is"},{"startTime":544.59,"endTime":547.98,"body":"Charles David Keeling's son,"},{"startTime":547.98,"endTime":552.79,"body":"who took over the job of"},{"startTime":547.98,"endTime":552.79,"body":"monitoring carbon dioxide"},{"startTime":554.357,"endTime":558.24,"body":"in Hawaii and actually"},{"startTime":554.357,"endTime":558.24,"body":"added a twist of his own."},{"startTime":558.24,"endTime":561.675,"body":"He started measuring oxygen concentrations"},{"startTime":561.675,"endTime":563.67,"body":"in the atmosphere."},{"startTime":563.67,"endTime":565.868,"body":"And this is why everybody really"},{"startTime":563.67,"endTime":565.868,"body":"panics because they think,"},{"startTime":565.868,"endTime":568.17,"body":"oh, we're going to, you know,"},{"startTime":565.868,"endTime":568.17,"body":"we're running out of oxygen,"},{"startTime":568.17,"endTime":569.04,"body":"we're all going to die."},{"startTime":569.04,"endTime":570.6,"body":"Don't panic."},{"startTime":570.6,"endTime":573.18,"body":"The changes he was measuring."},{"startTime":573.18,"endTime":575.67,"body":"This is a tremendously"},{"startTime":573.18,"endTime":575.67,"body":"impressive measurement,"},{"startTime":575.67,"endTime":577.14,"body":"these blue line here,"},{"startTime":577.14,"endTime":581.01,"body":"which is a measurement of"},{"startTime":577.14,"endTime":581.01,"body":"the falling concentration"},{"startTime":581.01,"endTime":583.47,"body":"of oxygen in the atmosphere."},{"startTime":583.47,"endTime":585.93,"body":"And you should expect he was,"},{"startTime":585.93,"endTime":589.5,"body":"he expected to find this"},{"startTime":585.93,"endTime":589.5,"body":"because when you make"},{"startTime":589.5,"endTime":594.21,"body":"a carbon dioxide molecule,"},{"startTime":589.5,"endTime":594.21,"body":"of course, by burning carbon,"},{"startTime":594.21,"endTime":597.06,"body":"you need a molecule of oxygen."},{"startTime":597.06,"endTime":600.27,"body":"C plus O2 two makes CO2."},{"startTime":600.27,"endTime":602.82,"body":"So you should expect that oxygen's"},{"startTime":602.82,"endTime":604.56,"body":"got to come from somewhere."},{"startTime":604.56,"endTime":607.5,"body":"It comes from the atmosphere."},{"startTime":607.5,"endTime":609.6,"body":"And, but the difficulty,"},{"startTime":609.6,"endTime":612.99,"body":"the reason this is a such"},{"startTime":609.6,"endTime":612.99,"body":"an impressive observation"},{"startTime":612.99,"endTime":616.47,"body":"is that there wasn't that"},{"startTime":612.99,"endTime":616.47,"body":"much carbon dioxide there"},{"startTime":616.47,"endTime":617.303,"body":"to start with."},{"startTime":617.303,"endTime":621.36,"body":"So you could detect it going"},{"startTime":617.303,"endTime":621.36,"body":"up, it's gone up by 30,"},{"startTime":621.36,"endTime":626.36,"body":"40% or so in the course"},{"startTime":621.36,"endTime":626.36,"body":"of David Keeling's record."},{"startTime":626.85,"endTime":631.85,"body":"But oxygen, over 20% of"},{"startTime":626.85,"endTime":631.85,"body":"the atmosphere is oxygen."},{"startTime":632.04,"endTime":633.87,"body":"So you are detecting a very,"},{"startTime":633.87,"endTime":638.87,"body":"very small reduction in the"},{"startTime":633.87,"endTime":638.87,"body":"concentration of oxygen,"},{"startTime":639.53,"endTime":643.74,"body":"but it's exactly the amount you'd expect"},{"startTime":643.74,"endTime":648.74,"body":"if the carbon dioxide is"},{"startTime":643.74,"endTime":648.74,"body":"coming from burning something."},{"startTime":648.87,"endTime":652.44,"body":"And we know what we're"},{"startTime":648.87,"endTime":652.44,"body":"burning because of this curve"},{"startTime":652.44,"endTime":657.44,"body":"at the bottom here, which"},{"startTime":652.44,"endTime":657.44,"body":"shows the isotopic signature,"},{"startTime":658.545,"endTime":661.53,"body":"the fraction of Carbon-13,"},{"startTime":661.53,"endTime":664.53,"body":"which is a radioactive form of carbon"},{"startTime":664.53,"endTime":667.046,"body":"that we see in the atmosphere."},{"startTime":667.046,"endTime":670.44,"body":"And that fraction is going down."},{"startTime":670.44,"endTime":673.59,"body":"And the reason we"},{"startTime":670.44,"endTime":673.59,"body":"understand it is going down"},{"startTime":673.59,"endTime":677.79,"body":"is because fossil carbon"},{"startTime":673.59,"endTime":677.79,"body":"has sat underground"},{"startTime":677.79,"endTime":679.29,"body":"for millions of years,"},{"startTime":679.29,"endTime":682.47,"body":"has very little radioactivity left in it,"},{"startTime":682.47,"endTime":685.503,"body":"whereas the natural carbon in the,"},{"startTime":686.37,"endTime":687.45,"body":"it's all natural carbon,"},{"startTime":687.45,"endTime":690.0,"body":"but the carbon dioxide that occurs"},{"startTime":690.0,"endTime":692.3,"body":"or that occurred already in the atmosphere"},{"startTime":692.3,"endTime":694.86,"body":"is being irradiated all"},{"startTime":692.3,"endTime":694.86,"body":"the time from the sun."},{"startTime":694.86,"endTime":697.56,"body":"So it's got a certain"},{"startTime":694.86,"endTime":697.56,"body":"amount of radioactivity,"},{"startTime":697.56,"endTime":700.83,"body":"of radioactive Carbon-13 in it."},{"startTime":700.83,"endTime":703.32,"body":"So as we add fossil carbon,"},{"startTime":703.32,"endTime":707.37,"body":"which has no radioactive"},{"startTime":703.32,"endTime":707.37,"body":"Carbon-13 in it to the atmosphere,"},{"startTime":707.37,"endTime":710.403,"body":"we see this Carbon-13 fraction going down."},{"startTime":711.742,"endTime":714.12,"body":"So it's all kind of belt-and-braces stuff"},{"startTime":714.12,"endTime":716.31,"body":"because it was pretty"},{"startTime":714.12,"endTime":716.31,"body":"obvious to start with"},{"startTime":716.31,"endTime":717.69,"body":"what was driving it."},{"startTime":717.69,"endTime":721.59,"body":"But this is just making it very clear."},{"startTime":721.59,"endTime":723.33,"body":"There's lots of lines of evidence."},{"startTime":723.33,"endTime":725.88,"body":"We know why the carbon dioxide's going up."},{"startTime":725.88,"endTime":729.003,"body":"It's going up because"},{"startTime":725.88,"endTime":729.003,"body":"we're burning fossil fuels."},{"startTime":730.14,"endTime":732.54,"body":"Of course, it's not just confirming that."},{"startTime":732.54,"endTime":735.072,"body":"What Ralph's observations"},{"startTime":732.54,"endTime":735.072,"body":"in particular did"},{"startTime":735.072,"endTime":737.01,"body":"was they allowed us,"},{"startTime":737.01,"endTime":740.849,"body":"they gave us an extra fix on how much"},{"startTime":740.849,"endTime":743.43,"body":"of the increase in carbon dioxide"},{"startTime":743.43,"endTime":746.46,"body":"was due to burning fossil fuels"},{"startTime":746.46,"endTime":750.75,"body":"and how much was due to burning forests"},{"startTime":750.75,"endTime":753.36,"body":"or land-use change or cutting down trees"},{"startTime":753.36,"endTime":756.3,"body":"because of course, a big chunk"},{"startTime":753.36,"endTime":756.3,"body":"of what we're putting into"},{"startTime":756.3,"endTime":760.74,"body":"the atmosphere does come"},{"startTime":756.3,"endTime":760.74,"body":"from land-use change."},{"startTime":760.74,"endTime":763.29,"body":"So this here from the"},{"startTime":760.74,"endTime":763.29,"body":"Global Carbon Project,"},{"startTime":763.29,"endTime":768.29,"body":"shows you how different sources"},{"startTime":763.29,"endTime":768.29,"body":"of carbon have contributed"},{"startTime":771.156,"endTime":773.973,"body":"to the increase we've"},{"startTime":771.156,"endTime":773.973,"body":"seen in the atmosphere."},{"startTime":775.17,"endTime":778.44,"body":"And you can see, the"},{"startTime":775.17,"endTime":778.44,"body":"usual suspects, coal, oil,"},{"startTime":778.44,"endTime":783.21,"body":"gas, others that's"},{"startTime":778.44,"endTime":783.21,"body":"primarily burning limestone"},{"startTime":783.21,"endTime":786.57,"body":"or heating limestone"},{"startTime":783.21,"endTime":786.57,"body":"to make lime for cement"},{"startTime":786.57,"endTime":788.55,"body":"that releases carbon dioxide."},{"startTime":788.55,"endTime":790.23,"body":"So that's what that gray wedge is."},{"startTime":790.23,"endTime":792.33,"body":"It's mostly cement production,"},{"startTime":792.33,"endTime":795.72,"body":"but this beige area here is emissions"},{"startTime":795.72,"endTime":798.36,"body":"due to changing land use."},{"startTime":798.36,"endTime":801.79,"body":"So cutting down trees to"},{"startTime":798.36,"endTime":801.79,"body":"clear land for agriculture"},{"startTime":804.191,"endTime":807.42,"body":"or changing agricultural practices,"},{"startTime":807.42,"endTime":809.28,"body":"releasing carbon from soil."},{"startTime":809.28,"endTime":811.02,"body":"If you over-cultivate a region,"},{"startTime":811.02,"endTime":814.59,"body":"degrade the soil, that carbon"},{"startTime":811.02,"endTime":814.59,"body":"ends up in the atmosphere."},{"startTime":814.59,"endTime":819.197,"body":"This of course is coming from by recent,"},{"startTime":820.29,"endTime":822.45,"body":"it would've been taken"},{"startTime":820.29,"endTime":822.45,"body":"out of the atmosphere"},{"startTime":822.45,"endTime":824.52,"body":"fairly recently, this carbon."},{"startTime":824.52,"endTime":826.68,"body":"So that has a lower,"},{"startTime":826.68,"endTime":829.83,"body":"that has a higher Carbon-13 signature."},{"startTime":829.83,"endTime":832.86,"body":"So what Ralph's observations"},{"startTime":829.83,"endTime":832.86,"body":"and what the observations"},{"startTime":832.86,"endTime":837.39,"body":"of Carbon-13 help us to see is to confirm"},{"startTime":837.39,"endTime":840.15,"body":"exactly how much of the"},{"startTime":837.39,"endTime":840.15,"body":"carbon we're putting in"},{"startTime":840.15,"endTime":843.3,"body":"the atmosphere is coming from fossil fuels"},{"startTime":843.3,"endTime":846.99,"body":"and how much is coming from"},{"startTime":843.3,"endTime":846.99,"body":"changing land-use practices."},{"startTime":846.99,"endTime":851.99,"body":"And that's the ratio, it's"},{"startTime":846.99,"endTime":851.99,"body":"overwhelmingly fossil these days."},{"startTime":852.96,"endTime":856.56,"body":"Of course, what we really"},{"startTime":852.96,"endTime":856.56,"body":"need to think about,"},{"startTime":856.56,"endTime":859.05,"body":"because we'll emphasize"},{"startTime":856.56,"endTime":859.05,"body":"a lot in these lectures,"},{"startTime":859.05,"endTime":863.61,"body":"how car carbon dioxide has a"},{"startTime":859.05,"endTime":863.61,"body":"cumulative effect on climate."},{"startTime":863.61,"endTime":866.67,"body":"What matters is the total amount of carbon"},{"startTime":866.67,"endTime":867.93,"body":"you dump in the atmosphere."},{"startTime":867.93,"endTime":871.74,"body":"So this is just taking these data, okay,"},{"startTime":871.74,"endTime":876.03,"body":"so this is emissions every"},{"startTime":871.74,"endTime":876.03,"body":"year and just adding them up"},{"startTime":876.03,"endTime":879.51,"body":"over time to say where have"},{"startTime":876.03,"endTime":879.51,"body":"the emissions come from?"},{"startTime":879.51,"endTime":882.15,"body":"And we're not sort of differentiating,"},{"startTime":882.15,"endTime":885.465,"body":"we're just lumping all"},{"startTime":882.15,"endTime":885.465,"body":"the fossils together."},{"startTime":885.465,"endTime":887.58,"body":"And the land use, what's interesting here,"},{"startTime":887.58,"endTime":891.51,"body":"notice that up until 1960 or so,"},{"startTime":891.51,"endTime":895.62,"body":"cumulative land-use change"},{"startTime":891.51,"endTime":895.62,"body":"emissions were bigger"},{"startTime":895.62,"endTime":897.39,"body":"than fossil fuel emissions."},{"startTime":897.39,"endTime":900.39,"body":"So land use was the big driver up until"},{"startTime":900.39,"endTime":901.71,"body":"the mid-20th century."},{"startTime":901.71,"endTime":906.06,"body":"And it's only quite recently"},{"startTime":901.71,"endTime":906.06,"body":"that fossil fuels have taken"},{"startTime":906.06,"endTime":909.213,"body":"over and of course now"},{"startTime":906.06,"endTime":909.213,"body":"dominating the picture."},{"startTime":910.32,"endTime":912.72,"body":"It's also, not only do we"},{"startTime":910.32,"endTime":912.72,"body":"know where this carbon dioxide"},{"startTime":912.72,"endTime":916.59,"body":"has come from, we also"},{"startTime":912.72,"endTime":916.59,"body":"interestingly, we know exactly"},{"startTime":916.59,"endTime":920.01,"body":"because the fossil fuel"},{"startTime":916.59,"endTime":920.01,"body":"industry keeps good records."},{"startTime":920.01,"endTime":922.05,"body":"We know who owned it."},{"startTime":922.05,"endTime":925.77,"body":"And that wedge in there"},{"startTime":922.05,"endTime":925.77,"body":"is just, and for example,"},{"startTime":925.77,"endTime":928.77,"body":"carbon that is now in the"},{"startTime":925.77,"endTime":928.77,"body":"atmosphere or has been released"},{"startTime":928.77,"endTime":932.49,"body":"to the atmosphere that was"},{"startTime":928.77,"endTime":932.49,"body":"once owned by a product sold"},{"startTime":932.49,"endTime":935.43,"body":"by 90 odd companies in the world."},{"startTime":935.43,"endTime":938.043,"body":"So we know where this carbon's come from."},{"startTime":939.21,"endTime":943.2,"body":"Quite precisely, which is"},{"startTime":939.21,"endTime":943.2,"body":"important for what we do about it,"},{"startTime":943.2,"endTime":945.27,"body":"and we know where it's going."},{"startTime":945.27,"endTime":947.55,"body":"So if you look at this figure,"},{"startTime":947.55,"endTime":950.94,"body":"this shows you the"},{"startTime":947.55,"endTime":950.94,"body":"carbon that's accumulated"},{"startTime":950.94,"endTime":952.2,"body":"in the atmosphere."},{"startTime":952.2,"endTime":955.41,"body":"That's just the Keeling Curve again,"},{"startTime":955.41,"endTime":957.12,"body":"it's exactly the same shape as the curve"},{"startTime":957.12,"endTime":958.173,"body":"I showed you earlier."},{"startTime":959.67,"endTime":962.91,"body":"It's now in units of tons of CO2 here,"},{"startTime":962.91,"endTime":965.07,"body":"but that's just the same"},{"startTime":962.91,"endTime":965.07,"body":"as parts per million."},{"startTime":965.07,"endTime":967.293,"body":"There's a simple conversion there."},{"startTime":968.61,"endTime":972.16,"body":"And then the green wedge is"},{"startTime":968.61,"endTime":972.16,"body":"the carbon that's accumulated"},{"startTime":973.68,"endTime":978.18,"body":"into the land that's been"},{"startTime":973.68,"endTime":978.18,"body":"taken up by the land."},{"startTime":978.18,"endTime":979.62,"body":"And the blue is carbon."},{"startTime":979.62,"endTime":983.125,"body":"That's this extra carbon that"},{"startTime":979.62,"endTime":983.125,"body":"we've put into the atmosphere"},{"startTime":983.125,"endTime":986.46,"body":"that's been taken up by the ocean."},{"startTime":986.46,"endTime":990.78,"body":"And if you just, if I flick"},{"startTime":986.46,"endTime":990.78,"body":"between this slide and this one,"},{"startTime":990.78,"endTime":994.456,"body":"you can see that the dotted"},{"startTime":990.78,"endTime":994.456,"body":"line here is the total amount"},{"startTime":994.456,"endTime":999.456,"body":"we've released over the"},{"startTime":994.456,"endTime":999.456,"body":"past couple of centuries"},{"startTime":1001.32,"endTime":1004.7,"body":"and these three wedges"},{"startTime":1001.32,"endTime":1004.7,"body":"pretty much exactly add up"},{"startTime":1004.7,"endTime":1007.34,"body":"to the dashed line."},{"startTime":1007.34,"endTime":1010.67,"body":"And that small discrepancy"},{"startTime":1007.34,"endTime":1010.67,"body":"is a lot of people"},{"startTime":1010.67,"endTime":1011.66,"body":"still working on it."},{"startTime":1011.66,"endTime":1015.11,"body":"This is what the Global Carbon"},{"startTime":1011.66,"endTime":1015.11,"body":"Projects and Corinne Le Quere"},{"startTime":1015.11,"endTime":1017.87,"body":"and Pierre Friedlingstein"},{"startTime":1015.11,"endTime":1017.87,"body":"founded this project."},{"startTime":1017.87,"endTime":1021.59,"body":"And it's again, it's a"},{"startTime":1017.87,"endTime":1021.59,"body":"remarkable achievement"},{"startTime":1021.59,"endTime":1024.29,"body":"that we understand so well"},{"startTime":1024.29,"endTime":1028.07,"body":"what's happened to carbon"},{"startTime":1024.29,"endTime":1028.07,"body":"in our climate system"},{"startTime":1028.07,"endTime":1030.77,"body":"over the past century"},{"startTime":1028.07,"endTime":1030.77,"body":"because a lot of this is,"},{"startTime":1030.77,"endTime":1033.56,"body":"goes back a long way and well beyond"},{"startTime":1033.56,"endTime":1035.99,"body":"many standard records."},{"startTime":1035.99,"endTime":1037.64,"body":"The fact that we understand"},{"startTime":1035.99,"endTime":1037.64,"body":"what's going on now"},{"startTime":1037.64,"endTime":1039.77,"body":"is much less impressive than"},{"startTime":1037.64,"endTime":1039.77,"body":"the fact we can work out"},{"startTime":1039.77,"endTime":1042.38,"body":"what was going on back"},{"startTime":1039.77,"endTime":1042.38,"body":"in the mid-20th century"},{"startTime":1042.38,"endTime":1044.413,"body":"when there were all sorts"},{"startTime":1042.38,"endTime":1044.413,"body":"of things happening."},{"startTime":1046.295,"endTime":1050.87,"body":"And so, and, they're working"},{"startTime":1046.295,"endTime":1050.87,"body":"to close this gap even further."},{"startTime":1050.87,"endTime":1054.26,"body":"In fact, Pierre was complaining"},{"startTime":1050.87,"endTime":1054.26,"body":"that I still show this slide"},{"startTime":1054.26,"endTime":1055.58,"body":"because in fact, it's a bit better now"},{"startTime":1055.58,"endTime":1059.45,"body":"so that annoying discrepancy"},{"startTime":1055.58,"endTime":1059.45,"body":"is getting smaller."},{"startTime":1059.45,"endTime":1064.438,"body":"So I should stress that"},{"startTime":1059.45,"endTime":1064.438,"body":"point 'cause anyway,"},{"startTime":1064.438,"endTime":1066.083,"body":"but it's a nice, tidy slide."},{"startTime":1067.7,"endTime":1072.7,"body":"So the important, so what"},{"startTime":1067.7,"endTime":1072.7,"body":"we want to talk about now is"},{"startTime":1073.46,"endTime":1077.66,"body":"this carbon that's not"},{"startTime":1073.46,"endTime":1077.66,"body":"gone into the atmosphere,"},{"startTime":1077.66,"endTime":1081.757,"body":"but has gone into the land or the ocean."},{"startTime":1081.757,"endTime":1084.8,"body":"The land sink and the ocean sink"},{"startTime":1084.8,"endTime":1087.98,"body":"because they're, it's a source"},{"startTime":1087.98,"endTime":1092.21,"body":"of much unnecessary confusion."},{"startTime":1092.21,"endTime":1096.95,"body":"And for example, here's"},{"startTime":1092.21,"endTime":1096.95,"body":"one source of confusion"},{"startTime":1096.95,"endTime":1101.95,"body":"that this extra carbon going"},{"startTime":1096.95,"endTime":1101.95,"body":"into the land and the oceans"},{"startTime":1102.11,"endTime":1103.43,"body":"gives rise to."},{"startTime":1103.43,"endTime":1105.11,"body":"I've shown you this slide before,"},{"startTime":1105.11,"endTime":1107.88,"body":"I think in the opening"},{"startTime":1105.11,"endTime":1107.88,"body":"lecture and it goes back"},{"startTime":1108.933,"endTime":1113.933,"body":"to climate policy before we"},{"startTime":1108.933,"endTime":1113.933,"body":"realized the need for net zero."},{"startTime":1114.35,"endTime":1117.68,"body":"And I'm just picking it up"},{"startTime":1114.35,"endTime":1117.68,"body":"because it is representative"},{"startTime":1117.68,"endTime":1120.5,"body":"of the way people"},{"startTime":1117.68,"endTime":1120.5,"body":"thought about the problem"},{"startTime":1120.5,"endTime":1125.5,"body":"that we would need, they looked"},{"startTime":1120.5,"endTime":1125.5,"body":"at the emissions in 1990,"},{"startTime":1125.69,"endTime":1130.69,"body":"they realized that the oceans"},{"startTime":1125.69,"endTime":1130.69,"body":"were taking up about 50%,"},{"startTime":1132.86,"endTime":1135.38,"body":"the oceans and the land"},{"startTime":1132.86,"endTime":1135.38,"body":"biosphere between them"},{"startTime":1135.38,"endTime":1138.56,"body":"were taking up about 50% of the carbon"},{"startTime":1138.56,"endTime":1142.43,"body":"we were putting into the"},{"startTime":1138.56,"endTime":1142.43,"body":"atmosphere in the 1990s."},{"startTime":1142.43,"endTime":1145.13,"body":"And so it seemed perfectly logical to say,"},{"startTime":1145.13,"endTime":1148.82,"body":"well, if we reduce our emissions by 50%,"},{"startTime":1148.82,"endTime":1152.13,"body":"then concentrations in the"},{"startTime":1148.82,"endTime":1152.13,"body":"atmosphere will stop rising"},{"startTime":1153.668,"endTime":1154.553,"body":"in the oceans."},{"startTime":1156.16,"endTime":1159.05,"body":"And so, back in 1990, emissions were,"},{"startTime":1159.05,"endTime":1163.913,"body":"say maybe 30 billion tons"},{"startTime":1159.05,"endTime":1163.913,"body":"of carbon dioxide per year."},{"startTime":1165.882,"endTime":1168.98,"body":"15 billion tons were appearing"},{"startTime":1165.882,"endTime":1168.98,"body":"in the atmosphere every year."},{"startTime":1168.98,"endTime":1173.69,"body":"The other 15 billion tons were"},{"startTime":1168.98,"endTime":1173.69,"body":"being taken up by the oceans"},{"startTime":1173.69,"endTime":1175.91,"body":"and the land biosphere."},{"startTime":1175.91,"endTime":1179.14,"body":"And so, the sort of logic went, okay,"},{"startTime":1179.14,"endTime":1182.06,"body":"so if we reduce our emissions by 50%,"},{"startTime":1182.06,"endTime":1184.4,"body":"Mother Nature will take care of it."},{"startTime":1184.4,"endTime":1187.4,"body":"Concentrations in the"},{"startTime":1184.4,"endTime":1187.4,"body":"atmosphere will stop rising"},{"startTime":1187.4,"endTime":1188.75,"body":"and we're good."},{"startTime":1188.75,"endTime":1190.79,"body":"And you can see this was the scenario."},{"startTime":1190.79,"endTime":1192.14,"body":"They had a bit of an increase here,"},{"startTime":1192.14,"endTime":1195.29,"body":"but basically, they're"},{"startTime":1192.14,"endTime":1195.29,"body":"talking about the target"},{"startTime":1195.29,"endTime":1200.033,"body":"of climate policy being"},{"startTime":1195.29,"endTime":1200.033,"body":"something like a 50% reduction."},{"startTime":1201.9,"endTime":1204.533,"body":"As I say, that was the"},{"startTime":1201.9,"endTime":1204.533,"body":"goal before net zero."},{"startTime":1205.79,"endTime":1208.94,"body":"And it sounds like quite"},{"startTime":1205.79,"endTime":1208.94,"body":"a reasonable argument."},{"startTime":1208.94,"endTime":1212.45,"body":"I mean, nature is taking"},{"startTime":1208.94,"endTime":1212.45,"body":"up 15 billion tons"},{"startTime":1212.45,"endTime":1213.89,"body":"of carbon dioxide per year."},{"startTime":1213.89,"endTime":1216.08,"body":"This was a situation in the 1990s."},{"startTime":1216.08,"endTime":1220.67,"body":"So provided we get our"},{"startTime":1216.08,"endTime":1220.67,"body":"emissions below 15 billion tons,"},{"startTime":1220.67,"endTime":1221.93,"body":"we'll be good."},{"startTime":1221.93,"endTime":1226.433,"body":"Nature will sort of take care"},{"startTime":1221.93,"endTime":1226.433,"body":"of any further emissions."},{"startTime":1227.63,"endTime":1231.38,"body":"And understanding why this logic is wrong"},{"startTime":1231.38,"endTime":1234.786,"body":"is one of the main points,"},{"startTime":1231.38,"endTime":1234.786,"body":"probably the main point"},{"startTime":1234.786,"endTime":1236.48,"body":"of this lecture."},{"startTime":1236.48,"endTime":1239.48,"body":"So this is the point"},{"startTime":1236.48,"endTime":1239.48,"body":"where we need to go back"},{"startTime":1239.48,"endTime":1241.49,"body":"to our climate models."},{"startTime":1241.49,"endTime":1244.64,"body":"But now, the Gresham Carbon-Cycle Model,"},{"startTime":1244.64,"endTime":1247.19,"body":"and if you're thinking this"},{"startTime":1244.64,"endTime":1247.19,"body":"looks a little bit familiar,"},{"startTime":1247.19,"endTime":1250.19,"body":"yes, but there are differences."},{"startTime":1250.19,"endTime":1254.66,"body":"So do spot the differences"},{"startTime":1250.19,"endTime":1254.66,"body":"here between this model"},{"startTime":1254.66,"endTime":1257.87,"body":"and the model we were using to understand"},{"startTime":1257.87,"endTime":1261.8,"body":"the flow of energy through"},{"startTime":1257.87,"endTime":1261.8,"body":"the climate system."},{"startTime":1261.8,"endTime":1264.98,"body":"We're now going to introduce a"},{"startTime":1261.8,"endTime":1264.98,"body":"very similar model to understand"},{"startTime":1264.98,"endTime":1268.07,"body":"the flow of carbon through"},{"startTime":1264.98,"endTime":1268.07,"body":"the climate system."},{"startTime":1268.07,"endTime":1271.43,"body":"So the first important"},{"startTime":1268.07,"endTime":1271.43,"body":"difference is the fluid here"},{"startTime":1271.43,"endTime":1272.69,"body":"is blue, not red."},{"startTime":1272.69,"endTime":1275.543,"body":"That's so because it represents carbon,"},{"startTime":1276.65,"endTime":1279.325,"body":"and not thermal energy."},{"startTime":1279.325,"endTime":1282.29,"body":"But there are some other"},{"startTime":1279.325,"endTime":1282.29,"body":"really important differences"},{"startTime":1282.29,"endTime":1283.177,"body":"between this."},{"startTime":1283.177,"endTime":1286.07,"body":"I'm so tempted to ask"},{"startTime":1283.177,"endTime":1286.07,"body":"the audience what's more."},{"startTime":1286.07,"endTime":1287.9,"body":"But let me just set this"},{"startTime":1286.07,"endTime":1287.9,"body":"thing going so you can"},{"startTime":1287.9,"endTime":1290.243,"body":"sort of see it at work."},{"startTime":1296.403,"endTime":1299.99,"body":"And so, we got a low level"},{"startTime":1296.403,"endTime":1299.99,"body":"of emissions being pumped in"},{"startTime":1299.99,"endTime":1301.73,"body":"at the bottom of the atmosphere, okay?"},{"startTime":1301.73,"endTime":1304.31,"body":"So you can see as a result,"},{"startTime":1304.31,"endTime":1308.78,"body":"concentrations are"},{"startTime":1304.31,"endTime":1308.78,"body":"rising in the atmosphere,"},{"startTime":1308.78,"endTime":1311.99,"body":"but you may notice straight away only half"},{"startTime":1311.99,"endTime":1314.84,"body":"of what we're putting in the"},{"startTime":1311.99,"endTime":1314.84,"body":"atmosphere is staying there."},{"startTime":1316.04,"endTime":1317.987,"body":"Half of it's going over here,"},{"startTime":1317.987,"endTime":1320.386,"body":"but what's going to happen if I stop?"},{"startTime":1320.386,"endTime":1323.053,"body":"(machine whirs)"},{"startTime":1325.7,"endTime":1329.15,"body":"Well, it didn't take care of it"},{"startTime":1329.15,"endTime":1332.39,"body":"or if I, so, and let me just"},{"startTime":1329.15,"endTime":1332.39,"body":"do a different experiment."},{"startTime":1332.39,"endTime":1335.243,"body":"And I'll start it going again."},{"startTime":1337.64,"endTime":1338.573,"body":"So here we go."},{"startTime":1342.118,"endTime":1343.55,"body":"So, we're emitting into the atmosphere,"},{"startTime":1343.55,"endTime":1347.09,"body":"only half of what we emit is"},{"startTime":1343.55,"endTime":1347.09,"body":"staying in the atmosphere,"},{"startTime":1347.09,"endTime":1348.38,"body":"but I'll just"},{"startTime":1348.38,"endTime":1351.74,"body":"(machine whirs)"},{"startTime":1351.74,"endTime":1354.81,"body":"halve the speed to see what happens."},{"startTime":1354.81,"endTime":1357.05,"body":"(machine whirs)"},{"startTime":1357.05,"endTime":1358.874,"body":"And it slows down"},{"startTime":1358.874,"endTime":1361.64,"body":"(machine whirs)"},{"startTime":1361.64,"endTime":1365.06,"body":"only slightly because"},{"startTime":1361.64,"endTime":1365.06,"body":"it won't receive that."},{"startTime":1365.06,"endTime":1366.894,"body":"Okay, sorry about this."},{"startTime":1366.894,"endTime":1368.12,"body":"(machine whirs)"},{"startTime":1368.12,"endTime":1368.953,"body":"And."},{"startTime":1371.63,"endTime":1373.94,"body":"Sorry, I hadn't rehearsed that one."},{"startTime":1373.94,"endTime":1375.95,"body":"It didn't go quite as planned."},{"startTime":1375.95,"endTime":1377.09,"body":"Okay."},{"startTime":1377.09,"endTime":1378.628,"body":"Because there's a minimum"},{"startTime":1377.09,"endTime":1378.628,"body":"speed and I was trying"},{"startTime":1378.628,"endTime":1379.76,"body":"to drop below it."},{"startTime":1379.76,"endTime":1380.66,"body":"Anyway."},{"startTime":1380.66,"endTime":1381.8,"body":"And so in order to,"},{"startTime":1381.8,"endTime":1384.41,"body":"so at this point, I'm going to"},{"startTime":1381.8,"endTime":1384.41,"body":"do something that'd be great"},{"startTime":1384.41,"endTime":1386.6,"body":"if we could do it in the real system,"},{"startTime":1386.6,"endTime":1387.96,"body":"which is to"},{"startTime":1389.307,"endTime":1392.12,"body":"pump it all out again"},{"startTime":1389.307,"endTime":1392.12,"body":"just to sort of reset,"},{"startTime":1392.12,"endTime":1393.442,"body":"reset the system."},{"startTime":1393.442,"endTime":1394.85,"body":"(machine whirs)"},{"startTime":1394.85,"endTime":1396.2,"body":"Yeah. Wouldn't it be"},{"startTime":1394.85,"endTime":1396.2,"body":"nice if we could do that"},{"startTime":1396.2,"endTime":1397.033,"body":"for the atmosphere as well?"},{"startTime":1397.033,"endTime":1399.87,"body":"We can, but it's a little bit harder"},{"startTime":1401.123,"endTime":1402.848,"body":"than just typing a command."},{"startTime":1402.848,"endTime":1404.637,"body":"(machine whirs)"},{"startTime":1404.637,"endTime":1407.146,"body":"And I'll just pull this down"},{"startTime":1407.146,"endTime":1409.813,"body":"(machine whirs)"},{"startTime":1411.95,"endTime":1413.88,"body":"so we can go back to where we started"},{"startTime":1414.759,"endTime":1417.934,"body":"(machine whirs)"},{"startTime":1417.934,"endTime":1420.17,"body":"and I'll talk you through the meaning"},{"startTime":1420.17,"endTime":1422.175,"body":"of these different parts of"},{"startTime":1422.175,"endTime":1424.917,"body":"(machine whirs)"},{"startTime":1424.917,"endTime":1426.083,"body":"the carbon cycle."},{"startTime":1430.414,"endTime":1434.78,"body":"Okay, so It's always a bit more"},{"startTime":1430.414,"endTime":1434.78,"body":"tense using this component,"},{"startTime":1434.78,"endTime":1438.32,"body":"this demonstration than the other one"},{"startTime":1438.32,"endTime":1440.85,"body":"because there's a crucial"},{"startTime":1438.32,"endTime":1440.85,"body":"element missing here"},{"startTime":1442.16,"endTime":1444.47,"body":"or I mean, it's accurate"},{"startTime":1442.16,"endTime":1444.47,"body":"that it's missing,"},{"startTime":1444.47,"endTime":1446.09,"body":"it's also missing in the real world."},{"startTime":1446.09,"endTime":1450.86,"body":"Remember the other Gresham"},{"startTime":1446.09,"endTime":1450.86,"body":"climate model we had,"},{"startTime":1450.86,"endTime":1453.29,"body":"which was the model of the flow of energy"},{"startTime":1453.29,"endTime":1454.7,"body":"through the climate system."},{"startTime":1454.7,"endTime":1456.53,"body":"It had an outlet over here,"},{"startTime":1456.53,"endTime":1458.483,"body":"energy was escaping back out in space."},{"startTime":1459.34,"endTime":1462.05,"body":"If you raised the level in the,"},{"startTime":1462.05,"endTime":1464.18,"body":"raised the temperature of the Earth,"},{"startTime":1464.18,"endTime":1467.15,"body":"it got rid of energy back"},{"startTime":1464.18,"endTime":1467.15,"body":"out into space faster"},{"startTime":1467.15,"endTime":1468.473,"body":"and it stopped rising."},{"startTime":1469.46,"endTime":1471.95,"body":"Well, if I do that"},{"startTime":1469.46,"endTime":1471.95,"body":"here, there's no outlet,"},{"startTime":1471.95,"endTime":1473.03,"body":"so it doesn't stop."},{"startTime":1473.03,"endTime":1474.65,"body":"That's the point."},{"startTime":1474.65,"endTime":1479.65,"body":"Carbon dioxide is completely"},{"startTime":1474.65,"endTime":1479.65,"body":"stable, it doesn't go anywhere."},{"startTime":1479.69,"endTime":1482.0,"body":"If you put carbon dioxide"},{"startTime":1479.69,"endTime":1482.0,"body":"into the atmosphere,"},{"startTime":1482.0,"endTime":1485.6,"body":"into the active climate"},{"startTime":1482.0,"endTime":1485.6,"body":"system, it stays there."},{"startTime":1485.6,"endTime":1490.6,"body":"It stays there until"},{"startTime":1485.6,"endTime":1490.6,"body":"it's reformed into rock,"},{"startTime":1490.91,"endTime":1494.93,"body":"which as you might imagine,"},{"startTime":1490.91,"endTime":1494.93,"body":"takes a very, very long time."},{"startTime":1494.93,"endTime":1499.58,"body":"So putting blue fluid into this system"},{"startTime":1499.58,"endTime":1501.56,"body":"is an irreversible process."},{"startTime":1501.56,"endTime":1504.56,"body":"Putting carbon dioxide into our atmosphere"},{"startTime":1504.56,"endTime":1507.166,"body":"into the active carbon cycle is also"},{"startTime":1507.166,"endTime":1509.663,"body":"an irreversible process."},{"startTime":1510.74,"endTime":1513.17,"body":"I can reverse it here because"},{"startTime":1510.74,"endTime":1513.17,"body":"I can change the direction,"},{"startTime":1513.17,"endTime":1515.66,"body":"but it's something I have to actively do."},{"startTime":1515.66,"endTime":1519.56,"body":"Whereas in the other model,"},{"startTime":1519.56,"endTime":1522.83,"body":"Mother Nature would sort of"},{"startTime":1519.56,"endTime":1522.83,"body":"get rid of a certain amount,"},{"startTime":1522.83,"endTime":1525.41,"body":"would just get rid of"},{"startTime":1522.83,"endTime":1525.41,"body":"energy faster for us."},{"startTime":1525.41,"endTime":1527.944,"body":"So that's an important first distinction."},{"startTime":1527.944,"endTime":1530.24,"body":"Let me tell you what the"},{"startTime":1527.944,"endTime":1530.24,"body":"different things mean here."},{"startTime":1530.24,"endTime":1531.262,"body":"So this over here,"},{"startTime":1531.262,"endTime":1535.52,"body":"this is the reservoir down"},{"startTime":1531.262,"endTime":1535.52,"body":"here is labeled the geosphere,"},{"startTime":1535.52,"endTime":1539.69,"body":"that's carbon underground,"},{"startTime":1535.52,"endTime":1539.69,"body":"carbon in rocks,"},{"startTime":1539.69,"endTime":1543.443,"body":"carbon in sediments, carbon"},{"startTime":1539.69,"endTime":1543.443,"body":"of course, in fossil fuels."},{"startTime":1545.037,"endTime":1548.243,"body":"Here is carbon dioxide in the atmosphere."},{"startTime":1549.56,"endTime":1554.56,"body":"Over here, is carbon dioxide"},{"startTime":1549.56,"endTime":1554.56,"body":"in the near-surface oceans"},{"startTime":1555.11,"endTime":1558.293,"body":"and the biosphere, mostly the biosphere."},{"startTime":1559.34,"endTime":1564.03,"body":"And over here, is carbon"},{"startTime":1559.34,"endTime":1564.03,"body":"dioxide in the deep oceans"},{"startTime":1564.95,"endTime":1567.35,"body":"and the amount of carbon dioxide here"},{"startTime":1567.35,"endTime":1568.97,"body":"we'll talk about in a minute."},{"startTime":1568.97,"endTime":1572.633,"body":"But again, if I just rerun the experiment,"},{"startTime":1574.22,"endTime":1578.12,"body":"remembering, I hope to get"},{"startTime":1574.22,"endTime":1578.12,"body":"the changing direction right,"},{"startTime":1578.12,"endTime":1579.35,"body":"here we are."},{"startTime":1579.35,"endTime":1582.35,"body":"So we're pumping carbon"},{"startTime":1579.35,"endTime":1582.35,"body":"dioxide into our atmosphere"},{"startTime":1582.35,"endTime":1585.11,"body":"and you'll notice that"},{"startTime":1582.35,"endTime":1585.11,"body":"concentrations are rising,"},{"startTime":1585.11,"endTime":1587.81,"body":"they're only rising at half the speed"},{"startTime":1587.81,"endTime":1590.63,"body":"that you would expect them to,"},{"startTime":1590.63,"endTime":1592.13,"body":"they're only rising at half the speed"},{"startTime":1592.13,"endTime":1595.28,"body":"as you expect 'em to rise if"},{"startTime":1592.13,"endTime":1595.28,"body":"all of what you were pumping in"},{"startTime":1595.28,"endTime":1596.81,"body":"was staying in the atmosphere."},{"startTime":1596.81,"endTime":1600.773,"body":"But if I were to stop emissions,"},{"startTime":1603.23,"endTime":1604.97,"body":"They don't,"},{"startTime":1604.97,"endTime":1608.2,"body":"it's not as if I was to"},{"startTime":1604.97,"endTime":1608.2,"body":"halve the rate of emissions,"},{"startTime":1608.2,"endTime":1610.34,"body":"it would just go up at half the speed."},{"startTime":1610.34,"endTime":1611.29,"body":"If I was to double the rate of emissions,"},{"startTime":1611.29,"endTime":1612.86,"body":"it goes up at double the speed."},{"startTime":1612.86,"endTime":1615.38,"body":"Okay, in fact, let's"},{"startTime":1612.86,"endTime":1615.38,"body":"do that and push it up"},{"startTime":1615.38,"endTime":1616.973,"body":"to a higher level."},{"startTime":1618.14,"endTime":1619.82,"body":"But I'll do this carefully"},{"startTime":1618.14,"endTime":1619.82,"body":"so I don't actually make"},{"startTime":1619.82,"endTime":1621.353,"body":"a huge mess."},{"startTime":1624.98,"endTime":1628.25,"body":"So this is, we've cranked"},{"startTime":1624.98,"endTime":1628.25,"body":"up our emissions now, okay?"},{"startTime":1628.25,"endTime":1630.443,"body":"And you can see,"},{"startTime":1631.539,"endTime":1633.53,"body":"it's a steady rate of emissions."},{"startTime":1633.53,"endTime":1635.33,"body":"Concentrations are rising"},{"startTime":1635.33,"endTime":1637.49,"body":"and watch carefully now what happens."},{"startTime":1637.49,"endTime":1639.683,"body":"I'm going to have to time"},{"startTime":1637.49,"endTime":1639.683,"body":"this right so that I make sure"},{"startTime":1639.683,"endTime":1643.237,"body":"that I don't let it all overflow,"},{"startTime":1643.237,"endTime":1646.07,"body":"but this is just, imagine"},{"startTime":1643.237,"endTime":1646.07,"body":"constant emissions"},{"startTime":1646.07,"endTime":1651.05,"body":"for a set period of time and then somehow,"},{"startTime":1651.05,"endTime":1653.54,"body":"I just switch off the emissions, okay?"},{"startTime":1653.54,"endTime":1655.64,"body":"Imagine being able to do"},{"startTime":1653.54,"endTime":1655.64,"body":"that in the real world."},{"startTime":1655.64,"endTime":1657.174,"body":"I'll do that here."},{"startTime":1657.174,"endTime":1660.41,"body":"(machine whirs)"},{"startTime":1660.41,"endTime":1662.75,"body":"Now look at what happens, okay?"},{"startTime":1662.75,"endTime":1667.4,"body":"There's a rapid fall over"},{"startTime":1662.75,"endTime":1667.4,"body":"a short period of time"},{"startTime":1667.4,"endTime":1670.913,"body":"and then it stops falling or does it?"},{"startTime":1672.56,"endTime":1674.9,"body":"I'll put my finger where it is."},{"startTime":1674.9,"endTime":1675.733,"body":"Okay."},{"startTime":1676.82,"endTime":1680.63,"body":"Notice it's still gradually falling, okay."},{"startTime":1680.63,"endTime":1684.56,"body":"Very slowly because through"},{"startTime":1680.63,"endTime":1684.56,"body":"exactly an analogous,"},{"startTime":1684.56,"endTime":1686.305,"body":"through exactly the same process actually,"},{"startTime":1686.305,"endTime":1687.95,"body":"that we were talking about,"},{"startTime":1687.95,"endTime":1691.91,"body":"about temperature being mixed"},{"startTime":1687.95,"endTime":1691.91,"body":"down into the deep ocean,"},{"startTime":1691.91,"endTime":1695.93,"body":"we're seeing carbon"},{"startTime":1691.91,"endTime":1695.93,"body":"being slowly mixed down"},{"startTime":1695.93,"endTime":1697.82,"body":"into the deep ocean."},{"startTime":1697.82,"endTime":1700.61,"body":"So if we stop emissions,"},{"startTime":1700.61,"endTime":1703.94,"body":"first of all, we get a rapid equilibration"},{"startTime":1703.94,"endTime":1706.16,"body":"between the atmosphere and the biosphere"},{"startTime":1706.16,"endTime":1708.29,"body":"and near-surface oceans."},{"startTime":1708.29,"endTime":1711.38,"body":"And then we see a very gradual decline"},{"startTime":1711.38,"endTime":1713.6,"body":"as the deep oceans"},{"startTime":1713.6,"endTime":1716.87,"body":"absorb more carbon from the surface."},{"startTime":1716.87,"endTime":1719.69,"body":"But it's not going to"},{"startTime":1716.87,"endTime":1719.69,"body":"go all the way back down"},{"startTime":1719.69,"endTime":1721.13,"body":"to pre-industrial."},{"startTime":1721.13,"endTime":1723.86,"body":"So pre-industrial was down here,"},{"startTime":1723.86,"endTime":1725.06,"body":"you can probably see by eye,"},{"startTime":1725.06,"endTime":1727.1,"body":"we'll leave it at it and"},{"startTime":1725.06,"endTime":1727.1,"body":"we'll see where it gets to."},{"startTime":1727.1,"endTime":1729.53,"body":"But you can see by eye where"},{"startTime":1727.1,"endTime":1729.53,"body":"it's what's going to happen,"},{"startTime":1729.53,"endTime":1733.01,"body":"we're going to end up"},{"startTime":1729.53,"endTime":1733.01,"body":"with permanently elevated"},{"startTime":1733.01,"endTime":1735.41,"body":"carbon dioxide concentrations"},{"startTime":1733.01,"endTime":1735.41,"body":"in the atmosphere."},{"startTime":1737.33,"endTime":1740.27,"body":"So just remind me what we hear."},{"startTime":1740.27,"endTime":1741.77,"body":"This is part number one,"},{"startTime":1741.77,"endTime":1745.01,"body":"additional carbon in the"},{"startTime":1741.77,"endTime":1745.01,"body":"atmosphere and the level indicates"},{"startTime":1745.01,"endTime":1747.244,"body":"the concentration in the atmosphere."},{"startTime":1747.244,"endTime":1750.41,"body":"Number two is additional"},{"startTime":1747.244,"endTime":1750.41,"body":"carbon in the biosphere"},{"startTime":1750.41,"endTime":1752.3,"body":"and the near-surface ocean."},{"startTime":1752.3,"endTime":1755.9,"body":"And the level indicates the"},{"startTime":1752.3,"endTime":1755.9,"body":"concentration of carbon dioxide"},{"startTime":1755.9,"endTime":1758.45,"body":"in the atmosphere that"},{"startTime":1755.9,"endTime":1758.45,"body":"would be in equilibrium"},{"startTime":1758.45,"endTime":1760.96,"body":"with that amount of"},{"startTime":1758.45,"endTime":1760.96,"body":"carbon in the biosphere"},{"startTime":1760.96,"endTime":1763.13,"body":"and near-surface ocean."},{"startTime":1763.13,"endTime":1766.1,"body":"As you think the concentration"},{"startTime":1763.13,"endTime":1766.1,"body":"of carbon dioxide in a plant"},{"startTime":1766.1,"endTime":1769.7,"body":"is a bit of a sort of odd,"},{"startTime":1766.1,"endTime":1769.7,"body":"so we can't, we don't,"},{"startTime":1769.7,"endTime":1771.92,"body":"we can't use that, but that's what I mean"},{"startTime":1771.92,"endTime":1773.72,"body":"by the level in that."},{"startTime":1773.72,"endTime":1775.58,"body":"And finally, the additional"},{"startTime":1773.72,"endTime":1775.58,"body":"carbon in the deep ocean."},{"startTime":1775.58,"endTime":1777.05,"body":"And likewise, the level indicates"},{"startTime":1777.05,"endTime":1780.263,"body":"that sort of equivalent"},{"startTime":1777.05,"endTime":1780.263,"body":"atmospheric CO2 concentration."},{"startTime":1782.03,"endTime":1784.643,"body":"So one question you might"},{"startTime":1782.03,"endTime":1784.643,"body":"ask, just looking at this,"},{"startTime":1785.604,"endTime":1788.3,"body":"if you're sort of a skeptical"},{"startTime":1785.604,"endTime":1788.3,"body":"bent is why's he made"},{"startTime":1788.3,"endTime":1790.4,"body":"the deep ocean so small,"},{"startTime":1790.4,"endTime":1792.14,"body":"because you probably know the deep oceans,"},{"startTime":1792.14,"endTime":1793.52,"body":"we emphasized that in the last lecture"},{"startTime":1793.52,"endTime":1796.1,"body":"how enormous the deep oceans are."},{"startTime":1796.1,"endTime":1800.477,"body":"And yet, this pipe is, its"},{"startTime":1796.1,"endTime":1800.477,"body":"area's what matters, of course."},{"startTime":1800.477,"endTime":1804.11,"body":"And the area of that pipe"},{"startTime":1800.477,"endTime":1804.11,"body":"is double the combined area"},{"startTime":1804.11,"endTime":1806.33,"body":"of those two pipes, but only double."},{"startTime":1806.33,"endTime":1809.33,"body":"See, I think why is it"},{"startTime":1806.33,"endTime":1809.33,"body":"not massively larger?"},{"startTime":1809.33,"endTime":1814.22,"body":"In fact, naturally, there"},{"startTime":1809.33,"endTime":1814.22,"body":"are 40-odd trillion tons"},{"startTime":1814.22,"endTime":1816.65,"body":"of natural carbon in the oceans,"},{"startTime":1816.65,"endTime":1819.95,"body":"that's equivalent to 148"},{"startTime":1816.65,"endTime":1819.95,"body":"trillion tons of CO2,"},{"startTime":1819.95,"endTime":1821.84,"body":"many, many times what's in the atmosphere"},{"startTime":1821.84,"endTime":1824.993,"body":"or even what's in total"},{"startTime":1821.84,"endTime":1824.993,"body":"fossil-fuel reserves."},{"startTime":1826.55,"endTime":1831.437,"body":"So why can't we rely on the"},{"startTime":1826.55,"endTime":1831.437,"body":"deep oceans to just dilute away"},{"startTime":1831.437,"endTime":1835.1,"body":"the carbon we put into"},{"startTime":1831.437,"endTime":1835.1,"body":"the system indefinitely?"},{"startTime":1835.1,"endTime":1836.505,"body":"And that's an important"},{"startTime":1835.1,"endTime":1836.505,"body":"question because for many,"},{"startTime":1836.505,"endTime":1838.91,"body":"many years people thought we could."},{"startTime":1838.91,"endTime":1841.34,"body":"Svante Arrhenius wasn't really worried"},{"startTime":1841.34,"endTime":1843.71,"body":"about carbon dioxide"},{"startTime":1841.34,"endTime":1843.71,"body":"concentrations going up very much"},{"startTime":1843.71,"endTime":1846.83,"body":"or he reckoned it would"},{"startTime":1843.71,"endTime":1846.83,"body":"take thousands of years,"},{"startTime":1846.83,"endTime":1849.32,"body":"although, so therefore his theory"},{"startTime":1849.32,"endTime":1852.26,"body":"about CO2 infecting climate was for him"},{"startTime":1852.26,"endTime":1856.613,"body":"a completely academic"},{"startTime":1852.26,"endTime":1856.613,"body":"idea because it wasn't,"},{"startTime":1857.81,"endTime":1859.55,"body":"he didn't expect it to happen"},{"startTime":1859.55,"endTime":1862.94,"body":"in any foreseeable timeframe"},{"startTime":1859.55,"endTime":1862.94,"body":"because he knew that there was"},{"startTime":1862.94,"endTime":1866.18,"body":"this amount and for many"},{"startTime":1862.94,"endTime":1866.18,"body":"years, that was the view."},{"startTime":1866.18,"endTime":1871.18,"body":"And it wasn't until Roger"},{"startTime":1866.18,"endTime":1871.18,"body":"Revelle came along in the 1950s"},{"startTime":1871.28,"endTime":1875.72,"body":"to point out a very important"},{"startTime":1871.28,"endTime":1875.72,"body":"aspect of ocean chemistry"},{"startTime":1875.72,"endTime":1876.98,"body":"that was also going on"},{"startTime":1876.98,"endTime":1879.62,"body":"as we raised carbon dioxide concentrations"},{"startTime":1879.62,"endTime":1882.53,"body":"in the atmosphere that was"},{"startTime":1879.62,"endTime":1882.53,"body":"likely to have an impact"},{"startTime":1882.53,"endTime":1886.28,"body":"on how much carbon the"},{"startTime":1882.53,"endTime":1886.28,"body":"oceans could absorb."},{"startTime":1886.28,"endTime":1888.2,"body":"And that's the fact that as we raise"},{"startTime":1888.2,"endTime":1890.75,"body":"carbon dioxide concentrations"},{"startTime":1888.2,"endTime":1890.75,"body":"in the atmosphere,"},{"startTime":1890.75,"endTime":1894.2,"body":"we're also acidifying the oceans"},{"startTime":1894.2,"endTime":1897.29,"body":"or perhaps more accurately,"},{"startTime":1894.2,"endTime":1897.29,"body":"making the oceans"},{"startTime":1897.29,"endTime":1899.12,"body":"slightly less alkaline."},{"startTime":1899.12,"endTime":1902.33,"body":"Dunno if you knew that the"},{"startTime":1899.12,"endTime":1902.33,"body":"oceans are not actually neutral,"},{"startTime":1902.33,"endTime":1906.01,"body":"they're slightly alkaline"},{"startTime":1902.33,"endTime":1906.01,"body":"and as we add carbon dioxide"},{"startTime":1906.01,"endTime":1910.532,"body":"to the system, we're making"},{"startTime":1906.01,"endTime":1910.532,"body":"them slightly less alkaline."},{"startTime":1910.532,"endTime":1913.28,"body":"But fortunately for us,"},{"startTime":1913.28,"endTime":1918.08,"body":"the oceans act as a giant buffer solution."},{"startTime":1918.08,"endTime":1919.76,"body":"So a bit like the antacid drink,"},{"startTime":1919.76,"endTime":1923.42,"body":"this chap who's clearly"},{"startTime":1919.76,"endTime":1923.42,"body":"had a bit of a heavy night"},{"startTime":1923.42,"endTime":1928.42,"body":"is taking, that neutralizes"},{"startTime":1923.42,"endTime":1928.42,"body":"a buffer solution,"},{"startTime":1930.654,"endTime":1934.28,"body":"neutralizes the addition"},{"startTime":1930.654,"endTime":1934.28,"body":"of acid or alkaline"},{"startTime":1934.28,"endTime":1937.76,"body":"and the oceans act as"},{"startTime":1934.28,"endTime":1937.76,"body":"a giant buffer solution"},{"startTime":1937.76,"endTime":1941.613,"body":"keeping ocean pH, the"},{"startTime":1937.76,"endTime":1941.613,"body":"acidity of the ocean's"},{"startTime":1941.613,"endTime":1944.12,"body":"relatively constant."},{"startTime":1944.12,"endTime":1945.62,"body":"Okay, it is changing,"},{"startTime":1945.62,"endTime":1948.53,"body":"but it's not changing nearly"},{"startTime":1945.62,"endTime":1948.53,"body":"as much as it would do"},{"startTime":1948.53,"endTime":1952.67,"body":"if the oceans didn't have"},{"startTime":1948.53,"endTime":1952.67,"body":"this buffering capability."},{"startTime":1952.67,"endTime":1954.98,"body":"And that's a very good thing"},{"startTime":1952.67,"endTime":1954.98,"body":"because if it wasn't for"},{"startTime":1954.98,"endTime":1957.62,"body":"the buffering capabilities of the oceans,"},{"startTime":1957.62,"endTime":1960.26,"body":"life could never have"},{"startTime":1957.62,"endTime":1960.26,"body":"evolved on this planet"},{"startTime":1960.26,"endTime":1965.18,"body":"because we need a very"},{"startTime":1960.26,"endTime":1965.18,"body":"constant pH environment."},{"startTime":1965.18,"endTime":1969.86,"body":"Well, the microbes needed a"},{"startTime":1965.18,"endTime":1969.86,"body":"very constant pH environment"},{"startTime":1969.86,"endTime":1972.05,"body":"in order to evolve in the first place."},{"startTime":1972.05,"endTime":1974.213,"body":"So it's a great thing the ocean does this,"},{"startTime":1975.453,"endTime":1979.91,"body":"but it does it at a cost in"},{"startTime":1975.453,"endTime":1979.91,"body":"that the oceans that limits"},{"startTime":1979.91,"endTime":1982.55,"body":"the amount of carbon dioxide"},{"startTime":1979.91,"endTime":1982.55,"body":"the oceans can absorb"},{"startTime":1982.55,"endTime":1985.4,"body":"'cause they're having to"},{"startTime":1982.55,"endTime":1985.4,"body":"work so hard to buffer"},{"startTime":1985.4,"endTime":1988.67,"body":"the change in pH that occurs as a result"},{"startTime":1988.67,"endTime":1990.95,"body":"of dissolving carbon dioxide."},{"startTime":1990.95,"endTime":1994.79,"body":"So that means that actually"},{"startTime":1990.95,"endTime":1994.79,"body":"when you take this into account,"},{"startTime":1994.79,"endTime":1999.32,"body":"oceans have a limited"},{"startTime":1994.79,"endTime":1999.32,"body":"ability to take up carbon"},{"startTime":1999.32,"endTime":2000.34,"body":"from the atmosphere."},{"startTime":2000.34,"endTime":2003.16,"body":"So if we look at what we expect to see,"},{"startTime":2003.16,"endTime":2005.17,"body":"do you remember when I"},{"startTime":2003.16,"endTime":2005.17,"body":"switched off emissions?"},{"startTime":2005.17,"endTime":2009.64,"body":"So this is a simulation,"},{"startTime":2005.17,"endTime":2009.64,"body":"lots of simulations, in fact."},{"startTime":2009.64,"endTime":2012.25,"body":"The gray band is sort of"},{"startTime":2009.64,"endTime":2012.25,"body":"the range of uncertainty"},{"startTime":2012.25,"endTime":2014.02,"body":"from lots and lots of different models."},{"startTime":2014.02,"endTime":2016.75,"body":"Simulation of what happens"},{"startTime":2014.02,"endTime":2016.75,"body":"when you put a whole lot"},{"startTime":2016.75,"endTime":2018.94,"body":"of carbon dioxide into the atmosphere"},{"startTime":2018.94,"endTime":2023.2,"body":"and then just see what happens"},{"startTime":2018.94,"endTime":2023.2,"body":"to concentrations after that."},{"startTime":2023.2,"endTime":2027.43,"body":"And just like our Gresham"},{"startTime":2023.2,"endTime":2027.43,"body":"Carbon-Cycle Model, it fell very,"},{"startTime":2027.43,"endTime":2031.36,"body":"falls very rapidly to start"},{"startTime":2027.43,"endTime":2031.36,"body":"with and then it starts to fall"},{"startTime":2031.36,"endTime":2033.13,"body":"much more slowly."},{"startTime":2033.13,"endTime":2034.36,"body":"And as you can see,"},{"startTime":2034.36,"endTime":2037.51,"body":"it's still falling in"},{"startTime":2034.36,"endTime":2037.51,"body":"the atmosphere but very,"},{"startTime":2037.51,"endTime":2039.73,"body":"very slowly indeed."},{"startTime":2039.73,"endTime":2040.563,"body":"Okay?"},{"startTime":2040.563,"endTime":2043.9,"body":"And in fact, that's after a hundred years."},{"startTime":2043.9,"endTime":2046.9,"body":"If we look over the first thousand years"},{"startTime":2046.9,"endTime":2050.44,"body":"and we add that sort of"},{"startTime":2046.9,"endTime":2050.44,"body":"this is the first 100 years,"},{"startTime":2050.44,"endTime":2052.24,"body":"I've just added it on here,"},{"startTime":2052.24,"endTime":2054.76,"body":"you can see it goes down"},{"startTime":2052.24,"endTime":2054.76,"body":"very rapidly to start with"},{"startTime":2054.76,"endTime":2057.28,"body":"and then very, very slowly indeed."},{"startTime":2057.28,"endTime":2061.03,"body":"And in fact, we can even look"},{"startTime":2057.28,"endTime":2061.03,"body":"over even longer time scales."},{"startTime":2061.03,"endTime":2064.21,"body":"And this was work done"},{"startTime":2061.03,"endTime":2064.21,"body":"largely by David Archer"},{"startTime":2064.21,"endTime":2066.91,"body":"in the 2000s about what,"},{"startTime":2066.91,"endTime":2070.75,"body":"he asked the question of"},{"startTime":2066.91,"endTime":2070.75,"body":"what actually happens to CO2"},{"startTime":2070.75,"endTime":2072.67,"body":"that we put into the atmosphere."},{"startTime":2072.67,"endTime":2074.17,"body":"And to start with,"},{"startTime":2074.17,"endTime":2078.01,"body":"it goes down through reactions"},{"startTime":2074.17,"endTime":2078.01,"body":"with calcium carbonates."},{"startTime":2078.01,"endTime":2080.95,"body":"And that's in David Archer's"},{"startTime":2078.01,"endTime":2080.95,"body":"terms, pretty quick."},{"startTime":2080.95,"endTime":2081.94,"body":"He's a geologist."},{"startTime":2081.94,"endTime":2084.643,"body":"So 2000 years is lightening quick,"},{"startTime":2086.751,"endTime":2089.8,"body":"But then he, beyond that, the only way"},{"startTime":2089.8,"endTime":2091.72,"body":"of getting rid of carbon dioxide"},{"startTime":2091.72,"endTime":2094.09,"body":"is reaction with igneous rocks."},{"startTime":2094.09,"endTime":2094.923,"body":"In other words,"},{"startTime":2094.923,"endTime":2098.51,"body":"basically turning carbon dioxide"},{"startTime":2094.923,"endTime":2098.51,"body":"back into the Earth's crust"},{"startTime":2099.546,"endTime":2101.26,"body":"and that takes a long time,"},{"startTime":2101.26,"endTime":2103.21,"body":"millions and millions of years."},{"startTime":2103.21,"endTime":2108.19,"body":"So that's the origin of"},{"startTime":2103.21,"endTime":2108.19,"body":"this completely irreversible"},{"startTime":2108.19,"endTime":2112.18,"body":"increase or irreversible over"},{"startTime":2108.19,"endTime":2112.18,"body":"any imaginable time scale"},{"startTime":2112.18,"endTime":2115.85,"body":"in carbon dioxide"},{"startTime":2112.18,"endTime":2115.85,"body":"concentrations that results from"},{"startTime":2119.65,"endTime":2122.863,"body":"its interaction with the geosphere."},{"startTime":2125.958,"endTime":2128.95,"body":"So that was sort of"},{"startTime":2125.958,"endTime":2128.95,"body":"the first hint I guess,"},{"startTime":2128.95,"endTime":2130.22,"body":"David Archer's work"},{"startTime":2132.858,"endTime":2136.54,"body":"and others before him, like"},{"startTime":2132.858,"endTime":2136.54,"body":"Siegenthaler and Oeschger"},{"startTime":2136.54,"endTime":2137.62,"body":"in the late 1980s."},{"startTime":2137.62,"endTime":2138.52,"body":"They did point out"},{"startTime":2139.937,"endTime":2141.1,"body":"that carbon dioxide"},{"startTime":2141.1,"endTime":2143.292,"body":"would have an irreversible impact"},{"startTime":2143.292,"endTime":2146.68,"body":"on climate and that therefore,"},{"startTime":2143.292,"endTime":2146.68,"body":"there must have been a limit"},{"startTime":2146.68,"endTime":2149.68,"body":"to how much we could"},{"startTime":2146.68,"endTime":2149.68,"body":"put into the atmosphere."},{"startTime":2149.68,"endTime":2152.08,"body":"But it was, they were very much talking"},{"startTime":2152.08,"endTime":2154.21,"body":"on geological time scales."},{"startTime":2154.21,"endTime":2157.69,"body":"And in the 2000s, this again, was seen"},{"startTime":2157.69,"endTime":2162.193,"body":"as a bit of a sort of theoretical issue,"},{"startTime":2165.72,"endTime":2168.34,"body":"but what was going to"},{"startTime":2165.72,"endTime":2168.34,"body":"happen on much more sort"},{"startTime":2168.34,"endTime":2170.35,"body":"of policy-relevant time scale,"},{"startTime":2170.35,"endTime":2172.72,"body":"say the next sort of few decades"},{"startTime":2172.72,"endTime":2174.973,"body":"to couple of centuries or so."},{"startTime":2176.02,"endTime":2181.02,"body":"And this shows you what"},{"startTime":2176.02,"endTime":2181.02,"body":"this kind of system would do"},{"startTime":2181.42,"endTime":2186.22,"body":"if we were to put carbon into"},{"startTime":2181.42,"endTime":2186.22,"body":"it for a set period of time"},{"startTime":2186.22,"endTime":2188.32,"body":"and then switch it off again, okay?"},{"startTime":2188.32,"endTime":2189.55,"body":"And remember what it did,"},{"startTime":2189.55,"endTime":2193.79,"body":"it fell rapidly to start"},{"startTime":2189.55,"endTime":2193.79,"body":"with and then it levels off"},{"startTime":2194.65,"endTime":2198.52,"body":"and it's going to carry"},{"startTime":2194.65,"endTime":2198.52,"body":"on going down slowly,"},{"startTime":2198.52,"endTime":2200.92,"body":"but never go all the way back down to zero"},{"startTime":2200.92,"endTime":2202.513,"body":"for a very, very long time."},{"startTime":2204.75,"endTime":2207.762,"body":"So it's a, and that's the"},{"startTime":2204.75,"endTime":2207.762,"body":"concentration of carbon dioxide"},{"startTime":2207.762,"endTime":2209.353,"body":"in the atmosphere."},{"startTime":2210.79,"endTime":2215.79,"body":"And if we express this as the"},{"startTime":2210.79,"endTime":2215.79,"body":"impact on the energy imbalance"},{"startTime":2216.1,"endTime":2218.644,"body":"due to the excess carbon"},{"startTime":2216.1,"endTime":2218.644,"body":"dioxide in the atmosphere,"},{"startTime":2218.644,"endTime":2220.84,"body":"it's pretty much the same shape."},{"startTime":2220.84,"endTime":2223.99,"body":"There's a slight change in"},{"startTime":2220.84,"endTime":2223.99,"body":"shape because of what you may"},{"startTime":2223.99,"endTime":2226.33,"body":"remember from the second lecture."},{"startTime":2226.33,"endTime":2228.67,"body":"The fact that every"},{"startTime":2226.33,"endTime":2228.67,"body":"doubling of carbon dioxide"},{"startTime":2228.67,"endTime":2232.15,"body":"has the same impact as the"},{"startTime":2228.67,"endTime":2232.15,"body":"last on the energy budget."},{"startTime":2232.15,"endTime":2236.066,"body":"So there's a slight change"},{"startTime":2232.15,"endTime":2236.066,"body":"in shape between the impact"},{"startTime":2236.066,"endTime":2237.849,"body":"on the energy budget and the impact"},{"startTime":2237.849,"endTime":2239.83,"body":"on carbon uptake concentrations."},{"startTime":2239.83,"endTime":2242.683,"body":"But that's a detail for us now."},{"startTime":2244.48,"endTime":2246.64,"body":"So we can understand"},{"startTime":2244.48,"endTime":2246.64,"body":"this with an expression,"},{"startTime":2246.64,"endTime":2248.05,"body":"with an equation."},{"startTime":2248.05,"endTime":2253.01,"body":"The change in the height"},{"startTime":2248.05,"endTime":2253.01,"body":"of the fluid in this column"},{"startTime":2254.2,"endTime":2257.72,"body":"is equal to the amount"},{"startTime":2254.2,"endTime":2257.72,"body":"of fluid I'm pumping in"},{"startTime":2258.64,"endTime":2260.21,"body":"over a period of time"},{"startTime":2261.19,"endTime":2263.8,"body":"minus a small term"},{"startTime":2263.8,"endTime":2267.01,"body":"which corresponds to"},{"startTime":2263.8,"endTime":2267.01,"body":"the fluid trickling out"},{"startTime":2267.01,"endTime":2268.783,"body":"into the deep oceans."},{"startTime":2270.49,"endTime":2274.81,"body":"So that's a sensible"},{"startTime":2270.49,"endTime":2274.81,"body":"expression for the behavior"},{"startTime":2274.81,"endTime":2276.613,"body":"of the fluid in these pipes."},{"startTime":2277.96,"endTime":2282.67,"body":"And we can rearrange"},{"startTime":2277.96,"endTime":2282.67,"body":"that and say emissions in"},{"startTime":2282.67,"endTime":2286.45,"body":"is just the change plus this trickle out"},{"startTime":2286.45,"endTime":2288.013,"body":"into the deep ocean."},{"startTime":2290.14,"endTime":2291.123,"body":"Why is this relevant?"},{"startTime":2291.123,"endTime":2294.28,"body":"We can write down exactly"},{"startTime":2291.123,"endTime":2294.28,"body":"the same expression"},{"startTime":2294.28,"endTime":2296.44,"body":"for the carbon cycle."},{"startTime":2296.44,"endTime":2300.31,"body":"Emissions in is just the increase"},{"startTime":2300.31,"endTime":2305.31,"body":"in the energy imbalance over"},{"startTime":2300.31,"endTime":2305.31,"body":"a period plus the average,"},{"startTime":2308.335,"endTime":2311.53,"body":"some constant times the"},{"startTime":2308.335,"endTime":2311.53,"body":"average energy imbalance"},{"startTime":2311.53,"endTime":2313.09,"body":"over that period."},{"startTime":2313.09,"endTime":2315.82,"body":"You might think why is he"},{"startTime":2313.09,"endTime":2315.82,"body":"bamboozling us with this math?"},{"startTime":2315.82,"endTime":2318.76,"body":"So at this point, well, I"},{"startTime":2315.82,"endTime":2318.76,"body":"just want to remind you,"},{"startTime":2318.76,"endTime":2320.98,"body":"if you're looking at that expression,"},{"startTime":2320.98,"endTime":2322.36,"body":"does it remind you of anything?"},{"startTime":2322.36,"endTime":2324.25,"body":"Well, I'm hoping it does."},{"startTime":2324.25,"endTime":2327.01,"body":"So basically, if you"},{"startTime":2324.25,"endTime":2327.01,"body":"look, one of the things"},{"startTime":2327.01,"endTime":2330.91,"body":"you'll notice about this is"},{"startTime":2327.01,"endTime":2330.91,"body":"that if we shut that off,"},{"startTime":2330.91,"endTime":2334.69,"body":"if I set this to zero, then this change,"},{"startTime":2334.69,"endTime":2336.4,"body":"this has to be zero,"},{"startTime":2336.4,"endTime":2339.37,"body":"which means that this change has to be,"},{"startTime":2339.37,"endTime":2341.41,"body":"remember in the last lecture here,"},{"startTime":2341.41,"endTime":2345.22,"body":"this change has to be negative"},{"startTime":2341.41,"endTime":2345.22,"body":"because that is positive."},{"startTime":2345.22,"endTime":2350.05,"body":"They have to add up to zero"},{"startTime":2345.22,"endTime":2350.05,"body":"so we get a decline, okay?"},{"startTime":2350.05,"endTime":2353.14,"body":"A fractional decline once"},{"startTime":2350.05,"endTime":2353.14,"body":"this initial adjustment"},{"startTime":2353.14,"endTime":2357.28,"body":"is over of interestingly"},{"startTime":2353.14,"endTime":2357.28,"body":"about 0.3% per year,"},{"startTime":2357.28,"endTime":2360.523,"body":"that's a number you may remember"},{"startTime":2357.28,"endTime":2360.523,"body":"from the ocean's lecture."},{"startTime":2362.11,"endTime":2365.08,"body":"And you've seen an expression"},{"startTime":2362.11,"endTime":2365.08,"body":"rather like this before."},{"startTime":2365.08,"endTime":2366.843,"body":"This is what we said temperatures did"},{"startTime":2366.843,"endTime":2370.03,"body":"over decade to century time scales."},{"startTime":2370.03,"endTime":2372.7,"body":"Change in temperature is"},{"startTime":2370.03,"endTime":2372.7,"body":"proportional to the change"},{"startTime":2372.7,"endTime":2375.79,"body":"in energy imbalance plus the"},{"startTime":2372.7,"endTime":2375.79,"body":"term which is proportional"},{"startTime":2375.79,"endTime":2379.24,"body":"to the average energy"},{"startTime":2375.79,"endTime":2379.24,"body":"imbalance over a period."},{"startTime":2379.24,"endTime":2381.373,"body":"So when we put these things together,"},{"startTime":2382.42,"endTime":2384.8,"body":"temperature response to"},{"startTime":2382.42,"endTime":2384.8,"body":"forcing looks like that"},{"startTime":2385.87,"endTime":2389.29,"body":"and the forcing response to"},{"startTime":2385.87,"endTime":2389.29,"body":"emissions looks like that."},{"startTime":2389.29,"endTime":2393.52,"body":"You'll notice these expressions"},{"startTime":2389.29,"endTime":2393.52,"body":"look remarkably similar."},{"startTime":2393.52,"endTime":2398.35,"body":"Indeed, if these two"},{"startTime":2393.52,"endTime":2398.35,"body":"constants are the same"},{"startTime":2398.35,"endTime":2401.65,"body":"and we'll talk in the next"},{"startTime":2398.35,"endTime":2401.65,"body":"lecture about whether they are,"},{"startTime":2401.65,"endTime":2406.65,"body":"then we end up that the"},{"startTime":2401.65,"endTime":2406.65,"body":"warming cause by carbon dioxide"},{"startTime":2406.84,"endTime":2410.47,"body":"is very simply proportional"},{"startTime":2406.84,"endTime":2410.47,"body":"to the total amount"},{"startTime":2410.47,"endTime":2413.14,"body":"of carbon dioxide we"},{"startTime":2410.47,"endTime":2413.14,"body":"put into the atmosphere"},{"startTime":2413.14,"endTime":2416.38,"body":"over any multi-decade period."},{"startTime":2416.38,"endTime":2419.35,"body":"Now, I had to kind of speed through that"},{"startTime":2419.35,"endTime":2421.57,"body":"and we're going to go back"},{"startTime":2419.35,"endTime":2421.57,"body":"over that in the next lecture."},{"startTime":2421.57,"endTime":2425.23,"body":"So, if this was sort of"},{"startTime":2421.57,"endTime":2425.23,"body":"slightly bamboozling,"},{"startTime":2425.23,"endTime":2427.69,"body":"just contain your excitement"},{"startTime":2425.23,"endTime":2427.69,"body":"and we'll come back to all this"},{"startTime":2427.69,"endTime":2431.32,"body":"in the next legislature when"},{"startTime":2427.69,"endTime":2431.32,"body":"we bring the ocean system"},{"startTime":2431.32,"endTime":2434.38,"body":"and the carbon-cycle system together."},{"startTime":2434.38,"endTime":2439.38,"body":"So are we all done with the"},{"startTime":2434.38,"endTime":2439.38,"body":"carbon cycle and net zero?"},{"startTime":2439.647,"endTime":2443.29,"body":"Unfortunately, there's a problem"},{"startTime":2443.29,"endTime":2446.29,"body":"and now we're kind of"},{"startTime":2443.29,"endTime":2446.29,"body":"done with the science now."},{"startTime":2446.29,"endTime":2449.38,"body":"I'm getting on to what"},{"startTime":2446.29,"endTime":2449.38,"body":"people are doing with it"},{"startTime":2449.38,"endTime":2451.13,"body":"and what people are thinking about."},{"startTime":2453.14,"endTime":2455.143,"body":"So what do people,"},{"startTime":2456.04,"endTime":2460.9,"body":"policy makers, companies,"},{"startTime":2456.04,"endTime":2460.9,"body":"the world at the moment,"},{"startTime":2460.9,"endTime":2465.673,"body":"actually mean by net"},{"startTime":2460.9,"endTime":2465.673,"body":"carbon dioxide emissions?"},{"startTime":2467.041,"endTime":2468.52,"body":"You may think that's perfectly obvious."},{"startTime":2468.52,"endTime":2471.07,"body":"In fact, we thought it"},{"startTime":2468.52,"endTime":2471.07,"body":"was perfectly obvious"},{"startTime":2471.07,"endTime":2474.4,"body":"when we were doing this"},{"startTime":2471.07,"endTime":2474.4,"body":"work back in the 2000s."},{"startTime":2474.4,"endTime":2476.3,"body":"We never thought there was"},{"startTime":2474.4,"endTime":2476.3,"body":"really, it never occurred"},{"startTime":2476.3,"endTime":2478.78,"body":"to me personally,"},{"startTime":2478.78,"endTime":2480.85,"body":"to worry about what people meant"},{"startTime":2480.85,"endTime":2481.96,"body":"by carbon dioxide emissions."},{"startTime":2481.96,"endTime":2483.21,"body":"I thought it was obvious."},{"startTime":2484.24,"endTime":2485.89,"body":"You burn something, you"},{"startTime":2484.24,"endTime":2485.89,"body":"put it in the atmosphere,"},{"startTime":2485.89,"endTime":2486.84,"body":"that's an emission."},{"startTime":2489.109,"endTime":2492.61,"body":"Okay, well for us, for"},{"startTime":2489.109,"endTime":2492.61,"body":"carbon-cycle scientists,"},{"startTime":2492.61,"endTime":2496.48,"body":"it means net emissions means the emissions"},{"startTime":2496.48,"endTime":2500.38,"body":"that you cause by human activities minus"},{"startTime":2500.38,"endTime":2504.01,"body":"what you remove from the atmosphere also"},{"startTime":2504.01,"endTime":2506.41,"body":"as an immediate consequence"},{"startTime":2504.01,"endTime":2506.41,"body":"of human activities."},{"startTime":2506.41,"endTime":2509.861,"body":"So if I actively take carbon"},{"startTime":2506.41,"endTime":2509.861,"body":"dioxide out of the atmosphere"},{"startTime":2509.861,"endTime":2512.26,"body":"and get rid of it, that's a removal."},{"startTime":2512.26,"endTime":2514.513,"body":"That's what we called a removal."},{"startTime":2515.59,"endTime":2519.61,"body":"And these are emissions minus"},{"startTime":2515.59,"endTime":2519.61,"body":"removals resulting directly"},{"startTime":2519.61,"endTime":2523.03,"body":"from ongoing human activities."},{"startTime":2523.03,"endTime":2526.37,"body":"That's what we meant by an emission"},{"startTime":2527.29,"endTime":2528.373,"body":"or net emissions."},{"startTime":2530.95,"endTime":2533.11,"body":"For emissions accountants,"},{"startTime":2533.11,"endTime":2534.64,"body":"There isn't any accountants in the room,"},{"startTime":2534.64,"endTime":2538.45,"body":"but we're now going to get a"},{"startTime":2534.64,"endTime":2538.45,"body":"bit heavy on accountants here ."},{"startTime":2538.45,"endTime":2541.24,"body":"For emissions accountants,"},{"startTime":2541.24,"endTime":2546.24,"body":"they also include the"},{"startTime":2541.24,"endTime":2546.24,"body":"uptake of carbon dioxide"},{"startTime":2546.7,"endTime":2549.613,"body":"on so-called managed land."},{"startTime":2550.6,"endTime":2553.69,"body":"That's any land that"},{"startTime":2550.6,"endTime":2553.69,"body":"somebody declares they own"},{"startTime":2553.69,"endTime":2558.22,"body":"and they manage that results from"},{"startTime":2558.22,"endTime":2562.03,"body":"the impact of past emissions."},{"startTime":2562.03,"endTime":2567.03,"body":"So if I take a, remember that"},{"startTime":2562.03,"endTime":2567.03,"body":"amazing animation of the world"},{"startTime":2567.4,"endTime":2570.31,"body":"and how the trees were"},{"startTime":2567.4,"endTime":2570.31,"body":"absorbing all that carbon"},{"startTime":2570.31,"endTime":2573.433,"body":"in Northern Hemisphere, now"},{"startTime":2570.31,"endTime":2573.433,"body":"they're absorbing carbon,"},{"startTime":2574.51,"endTime":2575.8,"body":"remember, there's wedges as well."},{"startTime":2575.8,"endTime":2579.16,"body":"They're absorbing carbon at a"},{"startTime":2575.8,"endTime":2579.16,"body":"faster rate than they would be"},{"startTime":2579.16,"endTime":2582.07,"body":"if we hadn't raised carbon"},{"startTime":2579.16,"endTime":2582.07,"body":"dioxide in the atmosphere."},{"startTime":2582.07,"endTime":2583.54,"body":"In fact, we've got plenty"},{"startTime":2582.07,"endTime":2583.54,"body":"of evidence of this."},{"startTime":2583.54,"endTime":2585.14,"body":"Let me just go onto the evidence."},{"startTime":2586.311,"endTime":2590.53,"body":"Here's some pictures"},{"startTime":2586.311,"endTime":2590.53,"body":"of a undisturbed region"},{"startTime":2590.53,"endTime":2594.73,"body":"of African savannah, 1925, 1993, 2011."},{"startTime":2594.73,"endTime":2598.271,"body":"Look how the vegetation is"},{"startTime":2594.73,"endTime":2598.271,"body":"changing and we understand how,"},{"startTime":2598.271,"endTime":2600.1,"body":"why the vegetation's changing."},{"startTime":2600.1,"endTime":2602.32,"body":"It's changing because"},{"startTime":2600.1,"endTime":2602.32,"body":"there's more carbon dioxide"},{"startTime":2602.32,"endTime":2604.39,"body":"in the atmosphere and"},{"startTime":2602.32,"endTime":2604.39,"body":"trees like carbon dioxide,"},{"startTime":2604.39,"endTime":2608.08,"body":"they're growing faster"},{"startTime":2604.39,"endTime":2608.08,"body":"in certain conditions."},{"startTime":2608.08,"endTime":2609.64,"body":"If you're not limited by water,"},{"startTime":2609.64,"endTime":2612.61,"body":"if you're not limited"},{"startTime":2609.64,"endTime":2612.61,"body":"by lots of other things,"},{"startTime":2612.61,"endTime":2614.08,"body":"trees will grow faster,"},{"startTime":2614.08,"endTime":2615.7,"body":"plants will grow faster if you have"},{"startTime":2615.7,"endTime":2618.043,"body":"more carbon dioxide available."},{"startTime":2619.885,"endTime":2624.397,"body":"So they're doing this, I"},{"startTime":2619.885,"endTime":2624.397,"body":"would say perfectly naturally."},{"startTime":2626.637,"endTime":2630.22,"body":"And us naive scientists back in the 2000s"},{"startTime":2630.22,"endTime":2633.403,"body":"regarded this as natural."},{"startTime":2634.63,"endTime":2637.21,"body":"But of course, it's not exactly natural"},{"startTime":2637.21,"endTime":2640.51,"body":"because it's only"},{"startTime":2637.21,"endTime":2640.51,"body":"happening because we humans"},{"startTime":2640.51,"endTime":2643.4,"body":"have put more carbon"},{"startTime":2640.51,"endTime":2643.4,"body":"dioxide into the atmosphere"},{"startTime":2645.16,"endTime":2648.1,"body":"and this is why we were really naive,"},{"startTime":2648.1,"endTime":2651.59,"body":"of course, it's also"},{"startTime":2648.1,"endTime":2651.59,"body":"happening on somebody's land"},{"startTime":2653.5,"endTime":2656.84,"body":"and these days, carbon has a value"},{"startTime":2658.09,"endTime":2661.204,"body":"and if you can show that"},{"startTime":2658.09,"endTime":2661.204,"body":"carbon is being absorbed"},{"startTime":2661.204,"endTime":2663.46,"body":"on your land,"},{"startTime":2663.46,"endTime":2666.4,"body":"you can sell that carbon"},{"startTime":2663.46,"endTime":2666.4,"body":"on the offset markets"},{"startTime":2666.4,"endTime":2667.55,"body":"for a healthy sum"},{"startTime":2668.89,"endTime":2671.8,"body":"and suddenly, all land in the planet"},{"startTime":2671.8,"endTime":2674.332,"body":"is managed apart possibly"},{"startTime":2671.8,"endTime":2674.332,"body":"from Greenland and Antarctica"},{"startTime":2674.332,"endTime":2675.477,"body":"that nobody really cares about"},{"startTime":2675.477,"endTime":2678.58,"body":"'cause it doesn't really absorb"},{"startTime":2675.477,"endTime":2678.58,"body":"carbon in the first place."},{"startTime":2678.58,"endTime":2682.72,"body":"So we have a situation that everybody"},{"startTime":2682.72,"endTime":2685.24,"body":"is suddenly turning around"},{"startTime":2682.72,"endTime":2685.24,"body":"and saying, oh great,"},{"startTime":2685.24,"endTime":2687.64,"body":"there's all this carbon's being absorbed"},{"startTime":2687.64,"endTime":2690.463,"body":"by the oceans and by the land biosphere."},{"startTime":2691.54,"endTime":2693.04,"body":"So that's a negative emission"},{"startTime":2693.04,"endTime":2694.45,"body":"that we're going to take credit for that"},{"startTime":2694.45,"endTime":2697.663,"body":"and sell it to somebody"},{"startTime":2694.45,"endTime":2697.663,"body":"to offset their flight."},{"startTime":2699.49,"endTime":2701.71,"body":"You see where this is a problem?"},{"startTime":2701.71,"endTime":2705.73,"body":"Okay, who owns these helpful forests?"},{"startTime":2705.73,"endTime":2708.88,"body":"Well, Canada for example,"},{"startTime":2708.88,"endTime":2713.44,"body":"Canada's forests are absorbing"},{"startTime":2708.88,"endTime":2713.44,"body":"over 900 million tons"},{"startTime":2713.44,"endTime":2715.9,"body":"of carbon dioxide every year,"},{"startTime":2715.9,"endTime":2719.38,"body":"additional carbon dioxide"},{"startTime":2715.9,"endTime":2719.38,"body":"because of all the carbon dioxide"},{"startTime":2719.38,"endTime":2723.22,"body":"we've put into the atmosphere"},{"startTime":2719.38,"endTime":2723.22,"body":"over the past century."},{"startTime":2723.22,"endTime":2728.22,"body":"Canada's emissions are"},{"startTime":2723.22,"endTime":2728.22,"body":"about 730 million tons."},{"startTime":2728.74,"endTime":2732.13,"body":"So those lovely Canadians are"},{"startTime":2728.74,"endTime":2732.13,"body":"not causing climate change"},{"startTime":2732.13,"endTime":2734.29,"body":"at all or are they?"},{"startTime":2734.29,"endTime":2736.87,"body":"Okay, now we can be confident."},{"startTime":2736.87,"endTime":2738.7,"body":"Canadians are really nice people."},{"startTime":2738.7,"endTime":2739.96,"body":"Any Canadians in the room?"},{"startTime":2739.96,"endTime":2742.84,"body":"There's no way they would take advantage"},{"startTime":2742.84,"endTime":2746.51,"body":"of such an obvious colossal"},{"startTime":2742.84,"endTime":2746.51,"body":"accounting loophole"},{"startTime":2747.619,"endTime":2750.463,"body":"to declare themselves"},{"startTime":2747.619,"endTime":2750.463,"body":"net zero prematurely."},{"startTime":2751.657,"endTime":2754.477,"body":"Some other countries have large forests"},{"startTime":2754.477,"endTime":2757.21,"body":"and are taking a rather different line"},{"startTime":2757.21,"endTime":2759.22,"body":"in UNFCCC negotiations,"},{"startTime":2759.22,"endTime":2761.353,"body":"which is why we have a problem here."},{"startTime":2763.57,"endTime":2765.97,"body":"Are these really equivalent"},{"startTime":2763.57,"endTime":2765.97,"body":"activities, this,"},{"startTime":2765.97,"endTime":2767.23,"body":"now we're back to Canada now."},{"startTime":2767.23,"endTime":2768.67,"body":"I'm not going to say"},{"startTime":2767.23,"endTime":2768.67,"body":"anything controversial"},{"startTime":2768.67,"endTime":2769.813,"body":"about other countries."},{"startTime":2770.8,"endTime":2772.84,"body":"Canadian forests absorbing CO2,"},{"startTime":2772.84,"endTime":2775.78,"body":"Canadian tar sands releasing CO2."},{"startTime":2775.78,"endTime":2777.583,"body":"I mean, that's not net zero."},{"startTime":2778.63,"endTime":2780.793,"body":"Those activities do not net out."},{"startTime":2783.531,"endTime":2786.4,"body":"So this challenge we have is that"},{"startTime":2786.4,"endTime":2789.76,"body":"the carbon accounting systems we use,"},{"startTime":2789.76,"endTime":2791.53,"body":"the carbon accounting"},{"startTime":2789.76,"endTime":2791.53,"body":"systems that will be used"},{"startTime":2791.53,"endTime":2793.9,"body":"if you are tempted to"},{"startTime":2791.53,"endTime":2793.9,"body":"tick the box to say, yes,"},{"startTime":2793.9,"endTime":2795.34,"body":"I'd like to offset my flight."},{"startTime":2795.34,"endTime":2796.75,"body":"Next time you take a flight,"},{"startTime":2796.75,"endTime":2799.24,"body":"rest assured the person behind,"},{"startTime":2799.24,"endTime":2802.06,"body":"the company behind the"},{"startTime":2799.24,"endTime":2802.06,"body":"box tick will be using"},{"startTime":2802.06,"endTime":2804.1,"body":"a carbon accounting system"},{"startTime":2804.1,"endTime":2807.43,"body":"that is fully endorsed by UK government,"},{"startTime":2807.43,"endTime":2811.72,"body":"UNFCCC, everybody else that"},{"startTime":2807.43,"endTime":2811.72,"body":"allows them to take credit"},{"startTime":2811.72,"endTime":2815.83,"body":"for this carbon that's being"},{"startTime":2811.72,"endTime":2815.83,"body":"taken up by managed land"},{"startTime":2815.83,"endTime":2817.72,"body":"that is happening entirely natural."},{"startTime":2817.72,"endTime":2819.91,"body":"Well, not entirely naturally."},{"startTime":2819.91,"endTime":2823.3,"body":"It's happening because"},{"startTime":2819.91,"endTime":2823.3,"body":"we've put carbon dioxide"},{"startTime":2823.3,"endTime":2825.55,"body":"into the system, so"},{"startTime":2823.3,"endTime":2825.55,"body":"trees are growing faster."},{"startTime":2826.614,"endTime":2828.343,"body":"And of course, if we look at,"},{"startTime":2829.781,"endTime":2831.7,"body":"this is the part that's being taken up."},{"startTime":2831.7,"endTime":2834.91,"body":"There's all this in unmanaged"},{"startTime":2831.7,"endTime":2834.91,"body":"land and there's all this"},{"startTime":2834.91,"endTime":2836.62,"body":"going into the oceans that so far,"},{"startTime":2836.62,"endTime":2838.63,"body":"nobody's taking credit for,"},{"startTime":2838.63,"endTime":2841.51,"body":"but it's only a matter"},{"startTime":2838.63,"endTime":2841.51,"body":"of time before everybody"},{"startTime":2841.51,"endTime":2843.55,"body":"wants to start taking"},{"startTime":2841.51,"endTime":2843.55,"body":"credit for carbon uptake"},{"startTime":2843.55,"endTime":2845.29,"body":"on managed oceans."},{"startTime":2845.29,"endTime":2846.123,"body":"Watch this space,"},{"startTime":2846.123,"endTime":2850.06,"body":"it's bound to happen and"},{"startTime":2846.123,"endTime":2850.06,"body":"30% of the world's oceans"},{"startTime":2850.06,"endTime":2852.34,"body":"are in somebody's economic exclusion zone."},{"startTime":2852.34,"endTime":2853.51,"body":"So that country will say, right,"},{"startTime":2853.51,"endTime":2856.06,"body":"we want to take credit for this sink."},{"startTime":2856.06,"endTime":2858.19,"body":"And if that's then used offset,"},{"startTime":2858.19,"endTime":2862.45,"body":"ongoing fossil-fuel emissions,"},{"startTime":2858.19,"endTime":2862.45,"body":"we end up with net zero,"},{"startTime":2862.45,"endTime":2865.78,"body":"not really meaning what"},{"startTime":2862.45,"endTime":2865.78,"body":"we meant by it at all."},{"startTime":2865.78,"endTime":2869.02,"body":"That's the natural uptake, quotes natural,"},{"startTime":2869.02,"endTime":2871.93,"body":"because obviously, it's"},{"startTime":2869.02,"endTime":2871.93,"body":"not entirely natural uptake"},{"startTime":2871.93,"endTime":2874.21,"body":"due to past CO2 emissions."},{"startTime":2874.21,"endTime":2878.32,"body":"And of course, that's what would"},{"startTime":2874.21,"endTime":2878.32,"body":"happen if we allowed people"},{"startTime":2878.32,"endTime":2881.83,"body":"to carry on burning fossil"},{"startTime":2878.32,"endTime":2881.83,"body":"fuels saying it's good"},{"startTime":2881.83,"endTime":2884.17,"body":"as long as you've offset"},{"startTime":2881.83,"endTime":2884.17,"body":"it with this stuff"},{"startTime":2884.17,"endTime":2886.63,"body":"that's being taken up by the natural sinks"},{"startTime":2886.63,"endTime":2889.12,"body":"because then you wouldn't"},{"startTime":2886.63,"endTime":2889.12,"body":"ever get any decline at all"},{"startTime":2889.12,"endTime":2891.001,"body":"because you'd just be"},{"startTime":2889.12,"endTime":2891.001,"body":"allowing the fossil fuels"},{"startTime":2891.001,"endTime":2894.403,"body":"to be carried on being"},{"startTime":2891.001,"endTime":2894.403,"body":"burnt to balance it."},{"startTime":2894.403,"endTime":2896.023,"body":"So that's where we're at."},{"startTime":2897.73,"endTime":2899.47,"body":"We need to get back,"},{"startTime":2899.47,"endTime":2904.47,"body":"I think to what we originally"},{"startTime":2899.47,"endTime":2904.47,"body":"meant by net CO2 emissions,"},{"startTime":2905.74,"endTime":2909.76,"body":"i.e. the net consequences"},{"startTime":2905.74,"endTime":2909.76,"body":"of our actual activities,"},{"startTime":2909.76,"endTime":2911.11,"body":"what we did last year,"},{"startTime":2911.11,"endTime":2913.57,"body":"not just the consequences"},{"startTime":2911.11,"endTime":2913.57,"body":"of what we've done"},{"startTime":2913.57,"endTime":2915.897,"body":"over the past 150 years."},{"startTime":2915.897,"endTime":2919.903,"body":"Recent paper by Felipe Grassi"},{"startTime":2915.897,"endTime":2919.903,"body":"drawing attention to this."},{"startTime":2921.43,"endTime":2924.79,"body":"They've done a great job of"},{"startTime":2921.43,"endTime":2924.79,"body":"documenting this problem,"},{"startTime":2924.79,"endTime":2925.9,"body":"but they say don't worry about it"},{"startTime":2925.9,"endTime":2927.58,"body":"because it's all going"},{"startTime":2925.9,"endTime":2927.58,"body":"to go away soon anyway,"},{"startTime":2927.58,"endTime":2929.765,"body":"'cause as the world"},{"startTime":2927.58,"endTime":2929.765,"body":"warms, trees won't be able"},{"startTime":2929.765,"endTime":2932.47,"body":"to absorb so much carbon anyway."},{"startTime":2932.47,"endTime":2934.54,"body":"So the loophole will close."},{"startTime":2934.54,"endTime":2936.16,"body":"I don't like this logic because it's"},{"startTime":2936.16,"endTime":2938.53,"body":"a little bit like saying"},{"startTime":2936.16,"endTime":2938.53,"body":"we've got this great loophole"},{"startTime":2938.53,"endTime":2939.94,"body":"that we can take advantage of now,"},{"startTime":2939.94,"endTime":2941.89,"body":"but the next generation won't be able to."},{"startTime":2941.89,"endTime":2943.097,"body":"So we're good."},{"startTime":2943.097,"endTime":2945.4,"body":"So let's exploit it as hard as we can."},{"startTime":2945.4,"endTime":2947.5,"body":"I think that's the"},{"startTime":2945.4,"endTime":2947.5,"body":"certain sort of problem."},{"startTime":2947.5,"endTime":2951.07,"body":"It's problematic, it"},{"startTime":2947.5,"endTime":2951.07,"body":"seems to me, that logic"},{"startTime":2951.07,"endTime":2952.18,"body":"and plus anyway,"},{"startTime":2952.18,"endTime":2955.03,"body":"if we count on this loophole"},{"startTime":2952.18,"endTime":2955.03,"body":"all the time and we use all"},{"startTime":2955.03,"endTime":2956.307,"body":"these natural uptakes"},{"startTime":2957.813,"endTime":2960.257,"body":"to offset ongoing fossil-fuel emissions,"},{"startTime":2960.257,"endTime":2961.814,"body":"we're not going to get to,"},{"startTime":2961.814,"endTime":2964.03,"body":"we're not going to stabilize"},{"startTime":2961.814,"endTime":2964.03,"body":"temperatures anyway"},{"startTime":2964.03,"endTime":2968.17,"body":"because if all we do is"},{"startTime":2964.03,"endTime":2968.17,"body":"make concentrations constant"},{"startTime":2968.17,"endTime":2969.01,"body":"in the atmosphere,"},{"startTime":2969.01,"endTime":2971.653,"body":"temperatures will continue to rise."},{"startTime":2973.03,"endTime":2975.94,"body":"So that's the problem."},{"startTime":2975.94,"endTime":2980.86,"body":"There is a solution which is"},{"startTime":2975.94,"endTime":2980.86,"body":"to stop pretending that carbon"},{"startTime":2980.86,"endTime":2984.4,"body":"in the biosphere is somehow exchangeable,"},{"startTime":2984.4,"endTime":2989.17,"body":"fungible with carbon coming"},{"startTime":2984.4,"endTime":2989.17,"body":"out of the geosphere."},{"startTime":2989.17,"endTime":2993.16,"body":"Taking carbon out of the geosphere, rocks,"},{"startTime":2993.16,"endTime":2997.45,"body":"fossil fuels, and putting it"},{"startTime":2993.16,"endTime":2997.45,"body":"into the active carbon cycle"},{"startTime":2997.45,"endTime":2999.823,"body":"is an irreversible process."},{"startTime":3001.02,"endTime":3006.02,"body":"The only way to get these"},{"startTime":3001.02,"endTime":3006.02,"body":"concentrations back down again"},{"startTime":3006.12,"endTime":3008.64,"body":"is to pump it back out."},{"startTime":3008.64,"endTime":3012.15,"body":"So if I've put it in, I've"},{"startTime":3008.64,"endTime":3012.15,"body":"got to pump it back out,"},{"startTime":3012.15,"endTime":3016.65,"body":"back into the geosphere"},{"startTime":3012.15,"endTime":3016.65,"body":"taking credits for carbon"},{"startTime":3016.65,"endTime":3018.06,"body":"that's going into other parts"},{"startTime":3018.06,"endTime":3021.363,"body":"of the active carbon cycle doesn't cut it,"},{"startTime":3024.879,"endTime":3027.33,"body":"but we're going to have to work on that"},{"startTime":3027.33,"endTime":3030.57,"body":"because it is the way"},{"startTime":3027.33,"endTime":3030.57,"body":"everybody regards carbon"},{"startTime":3030.57,"endTime":3031.983,"body":"at the moment."},{"startTime":3034.213,"endTime":3037.74,"body":"And it's important to stress"},{"startTime":3034.213,"endTime":3037.74,"body":"promoting reabsorption"},{"startTime":3037.74,"endTime":3040.2,"body":"of carbon by the biosphere"},{"startTime":3037.74,"endTime":3040.2,"body":"through particularly,"},{"startTime":3040.2,"endTime":3044.34,"body":"nature-based solutions has"},{"startTime":3040.2,"endTime":3044.34,"body":"many wonderful benefits."},{"startTime":3044.34,"endTime":3047.82,"body":"And so I'm not saying"},{"startTime":3044.34,"endTime":3047.82,"body":"we shouldn't do that,"},{"startTime":3047.82,"endTime":3051.45,"body":"but what I am saying is we"},{"startTime":3047.82,"endTime":3051.45,"body":"shouldn't kid ourselves that that"},{"startTime":3051.45,"endTime":3056.4,"body":"is somehow compensating"},{"startTime":3051.45,"endTime":3056.4,"body":"for the impact of us"},{"startTime":3056.4,"endTime":3058.92,"body":"taking carbon out of the geosphere"},{"startTime":3058.92,"endTime":3062.613,"body":"and putting it into the"},{"startTime":3058.92,"endTime":3062.613,"body":"active carbon cycle."},{"startTime":3063.99,"endTime":3066.93,"body":"So here's a question."},{"startTime":3066.93,"endTime":3069.81,"body":"We have an energy bill before"},{"startTime":3066.93,"endTime":3069.81,"body":"Parliaments at the moment."},{"startTime":3069.81,"endTime":3072.087,"body":"The government has a golden opportunity"},{"startTime":3072.087,"endTime":3075.87,"body":"to embrace the concept"},{"startTime":3072.087,"endTime":3075.87,"body":"of geological net zero"},{"startTime":3075.87,"endTime":3079.65,"body":"as proposed in Chris Skidmore's review"},{"startTime":3079.65,"endTime":3082.89,"body":"of the UK's net-zero"},{"startTime":3079.65,"endTime":3082.89,"body":"target that was released"},{"startTime":3082.89,"endTime":3084.87,"body":"only a couple of months ago,"},{"startTime":3084.87,"endTime":3086.347,"body":"in which he expressly said,"},{"startTime":3086.347,"endTime":3089.01,"body":"\"Government should"},{"startTime":3086.347,"endTime":3089.01,"body":"recognize the importance"},{"startTime":3089.01,"endTime":3090.457,"body":"of geological net zero.\""},{"startTime":3090.457,"endTime":3092.55,"body":"That's a balance between"},{"startTime":3090.457,"endTime":3092.55,"body":"what's being taken out"},{"startTime":3092.55,"endTime":3094.8,"body":"of the geosphere and what's being actively"},{"startTime":3094.8,"endTime":3096.603,"body":"put back in the geosphere."},{"startTime":3097.987,"endTime":3098.94,"body":"\"And work to align"},{"startTime":3098.94,"endTime":3101.37,"body":"international ambitions towards geo zero,\""},{"startTime":3101.37,"endTime":3106.02,"body":"that's what he called it, \"by"},{"startTime":3101.37,"endTime":3106.02,"body":"2050, in line with net zero.\""},{"startTime":3106.02,"endTime":3110.58,"body":"So watch this space because our government"},{"startTime":3110.58,"endTime":3113.13,"body":"has an opportunity to do"},{"startTime":3110.58,"endTime":3113.13,"body":"something really historic here."},{"startTime":3113.13,"endTime":3115.86,"body":"We could be the first country in the world"},{"startTime":3115.86,"endTime":3119.2,"body":"to actually declare a goal"},{"startTime":3115.86,"endTime":3119.2,"body":"of geological net zero"},{"startTime":3121.47,"endTime":3126.09,"body":"and that's what it'll actually"},{"startTime":3121.47,"endTime":3126.09,"body":"take to stop global warming."},{"startTime":3126.09,"endTime":3128.31,"body":"So if we were the first to declare it,"},{"startTime":3128.31,"endTime":3130.23,"body":"eventually, all countries"},{"startTime":3128.31,"endTime":3130.23,"body":"will have to declare"},{"startTime":3130.23,"endTime":3133.62,"body":"for geological net zero and"},{"startTime":3130.23,"endTime":3133.62,"body":"Britain could be the first,"},{"startTime":3133.62,"endTime":3134.73,"body":"which would be fitting 'cause after all,"},{"startTime":3134.73,"endTime":3136.77,"body":"we were kind of the first"},{"startTime":3134.73,"endTime":3136.77,"body":"to start the problem"},{"startTime":3136.77,"endTime":3140.173,"body":"in the first place."},{"startTime":3136.77,"endTime":3140.173,"body":"(audience laughs)"},{"startTime":3141.694,"endTime":3144.27,"body":"So that sort of concludes this lecture."},{"startTime":3144.27,"endTime":3146.482,"body":"Just to remind you what we've"},{"startTime":3144.27,"endTime":3146.482,"body":"covered in this lecture,"},{"startTime":3146.482,"endTime":3149.22,"body":"how is CO2 emissions are"},{"startTime":3146.482,"endTime":3149.22,"body":"distributed in the atmosphere"},{"startTime":3149.22,"endTime":3150.81,"body":"and biosphere in the oceans?"},{"startTime":3150.81,"endTime":3152.34,"body":"It's relatively simple,"},{"startTime":3152.34,"endTime":3153.84,"body":"relatively predictable,"},{"startTime":3153.84,"endTime":3156.36,"body":"but important and"},{"startTime":3153.84,"endTime":3156.36,"body":"important to understand it"},{"startTime":3156.36,"endTime":3159.78,"body":"and how fossil the release"},{"startTime":3156.36,"endTime":3159.78,"body":"of fossil carbon dioxide"},{"startTime":3159.78,"endTime":3161.283,"body":"has a permanent impact."},{"startTime":3162.36,"endTime":3164.28,"body":"I've stressed how accounting"},{"startTime":3162.36,"endTime":3164.28,"body":"for carbon dioxide"},{"startTime":3164.28,"endTime":3166.685,"body":"in the biosphere is a bit of a mess,"},{"startTime":3166.685,"endTime":3169.17,"body":"but I don't want just to take"},{"startTime":3166.685,"endTime":3169.17,"body":"away with you the message"},{"startTime":3169.17,"endTime":3170.524,"body":"that, oh, it's a bit of a"},{"startTime":3169.17,"endTime":3170.524,"body":"mess and it's complicated"},{"startTime":3170.524,"endTime":3172.5,"body":"and I don't want to think about it."},{"startTime":3172.5,"endTime":3175.32,"body":"There's something very"},{"startTime":3172.5,"endTime":3175.32,"body":"simple that we do need to do,"},{"startTime":3175.32,"endTime":3177.42,"body":"which is getting the accounting right"},{"startTime":3177.42,"endTime":3180.0,"body":"of carbon coming in and"},{"startTime":3177.42,"endTime":3180.0,"body":"out of the geosphere."},{"startTime":3180.0,"endTime":3183.93,"body":"We take carbon out of the"},{"startTime":3180.0,"endTime":3183.93,"body":"geosphere in only four forms, coal,"},{"startTime":3183.93,"endTime":3187.35,"body":"oil, natural gas, and"},{"startTime":3183.93,"endTime":3187.35,"body":"limestone for cement."},{"startTime":3187.35,"endTime":3189.66,"body":"We have right now we put"},{"startTime":3187.35,"endTime":3189.66,"body":"it back in only one form,"},{"startTime":3189.66,"endTime":3190.953,"body":"which is liquid CO2."},{"startTime":3191.815,"endTime":3193.95,"body":"If we want to stop global warming"},{"startTime":3193.95,"endTime":3196.17,"body":"those have to balance as"},{"startTime":3193.95,"endTime":3196.17,"body":"I emphasized right back"},{"startTime":3196.17,"endTime":3198.54,"body":"at the beginning of these lectures."},{"startTime":3198.54,"endTime":3203.4,"body":"And our government has an"},{"startTime":3198.54,"endTime":3203.4,"body":"opportunity right now to embrace"},{"startTime":3203.4,"endTime":3206.58,"body":"that idea and pioneer the roots towards"},{"startTime":3206.58,"endTime":3208.05,"body":"a stable climate future."},{"startTime":3208.05,"endTime":3209.4,"body":"Let's see what they do."},{"startTime":3209.4,"endTime":3210.466,"body":"Thank you."},{"startTime":3210.466,"endTime":3213.299,"body":"(audience claps)"},{"startTime":3220.021,"endTime":3221.37,"body":"- Thank you so much Professor Allen"},{"startTime":3221.37,"endTime":3222.36,"body":"for such a fascinating lecture."},{"startTime":3222.36,"endTime":3223.8,"body":"I've got a question for you online"},{"startTime":3223.8,"endTime":3225.81,"body":"and then perhaps we can go to the room."},{"startTime":3225.81,"endTime":3226.643,"body":"The question is,"},{"startTime":3226.643,"endTime":3228.75,"body":"what impact do you think"},{"startTime":3226.643,"endTime":3228.75,"body":"this rise in CO2 emissions"},{"startTime":3228.75,"endTime":3230.79,"body":"will have on the lives"},{"startTime":3228.75,"endTime":3230.79,"body":"of the next generation"},{"startTime":3230.79,"endTime":3231.84,"body":"and for example,"},{"startTime":3231.84,"endTime":3233.703,"body":"in terms of lifespan, et cetera?"},{"startTime":3234.69,"endTime":3238.564,"body":"- Well, the important, I mean,"},{"startTime":3238.564,"endTime":3241.47,"body":"there'll be many impacts"},{"startTime":3238.564,"endTime":3241.47,"body":"because every ton of CO2 we put"},{"startTime":3241.47,"endTime":3243.99,"body":"into the atmosphere drives"},{"startTime":3241.47,"endTime":3243.99,"body":"up global temperatures."},{"startTime":3243.99,"endTime":3246.81,"body":"And we'll talk about the"},{"startTime":3243.99,"endTime":3246.81,"body":"amount by which it drives it up"},{"startTime":3246.81,"endTime":3247.983,"body":"in the next lecture."},{"startTime":3250.386,"endTime":3253.05,"body":"But so clearly, the next"},{"startTime":3250.386,"endTime":3253.05,"body":"generation will be stuck"},{"startTime":3253.05,"endTime":3257.43,"body":"with the impacts of that"},{"startTime":3253.05,"endTime":3257.43,"body":"elevated global temperature"},{"startTime":3257.43,"endTime":3259.95,"body":"unless and until we work out how"},{"startTime":3259.95,"endTime":3263.73,"body":"to reverse the pump and literally"},{"startTime":3259.95,"endTime":3263.73,"body":"take that carbon dioxide"},{"startTime":3263.73,"endTime":3265.26,"body":"back out of the atmosphere."},{"startTime":3265.26,"endTime":3267.39,"body":"So that's the important thing"},{"startTime":3267.39,"endTime":3271.012,"body":"for everybody to understand"},{"startTime":3267.39,"endTime":3271.012,"body":"is that what we're doing now"},{"startTime":3271.012,"endTime":3273.354,"body":"is causing irreversible harm or harm"},{"startTime":3273.354,"endTime":3277.08,"body":"that can only be reversed"},{"startTime":3273.354,"endTime":3277.08,"body":"with a lot of work."},{"startTime":3277.08,"endTime":3279.36,"body":"I mean, getting carbon dioxide"},{"startTime":3277.08,"endTime":3279.36,"body":"back out of the atmosphere,"},{"startTime":3279.36,"endTime":3284.36,"body":"we will talk about this in"},{"startTime":3279.36,"endTime":3284.36,"body":"the last lecture, is hard"},{"startTime":3284.88,"endTime":3289.14,"body":"and it can be done but"},{"startTime":3284.88,"endTime":3289.14,"body":"bequeathing that task"},{"startTime":3289.14,"endTime":3290.73,"body":"to the next generation"},{"startTime":3289.14,"endTime":3290.73,"body":"or the next generation,"},{"startTime":3290.73,"endTime":3293.73,"body":"but one is rough on them"},{"startTime":3290.73,"endTime":3293.73,"body":"because it's a hard one."},{"startTime":3293.73,"endTime":3296.85,"body":"- [Audience] What extent does"},{"startTime":3293.73,"endTime":3296.85,"body":"the carbon cycle also extend"},{"startTime":3296.85,"endTime":3299.76,"body":"to other potent greenhouse"},{"startTime":3296.85,"endTime":3299.76,"body":"gases like methane"},{"startTime":3299.76,"endTime":3301.02,"body":"or other hydrocarbons which have"},{"startTime":3301.02,"endTime":3303.09,"body":"a higher global warming potential?"},{"startTime":3303.09,"endTime":3305.851,"body":"- Yep, so the methane"},{"startTime":3303.09,"endTime":3305.851,"body":"cycle is totally different"},{"startTime":3305.851,"endTime":3309.78,"body":"from the carbon cycle in"},{"startTime":3305.851,"endTime":3309.78,"body":"that when you put methane"},{"startTime":3309.78,"endTime":3311.04,"body":"into the climate system,"},{"startTime":3311.04,"endTime":3313.77,"body":"it's kind of as if"},{"startTime":3311.04,"endTime":3313.77,"body":"there's an outlet as well"},{"startTime":3313.77,"endTime":3317.61,"body":"because methane is oxidized"},{"startTime":3313.77,"endTime":3317.61,"body":"naturally to carbon dioxide,"},{"startTime":3317.61,"endTime":3320.583,"body":"which has a much lower"},{"startTime":3317.61,"endTime":3320.583,"body":"global warming potential."},{"startTime":3322.966,"endTime":3325.08,"body":"So it almost couldn't be more different."},{"startTime":3325.08,"endTime":3327.42,"body":"And that's a rather short"},{"startTime":3325.08,"endTime":3327.42,"body":"answer to your question"},{"startTime":3327.42,"endTime":3330.06,"body":"and there will be a whole lecture on,"},{"startTime":3330.06,"endTime":3332.4,"body":"when we come to year"},{"startTime":3330.06,"endTime":3332.4,"body":"three of these lectures"},{"startTime":3332.4,"endTime":3334.471,"body":"where we talk specifically about solutions"},{"startTime":3334.471,"endTime":3338.297,"body":"and the different aspects of"},{"startTime":3334.471,"endTime":3338.297,"body":"solutions to the climate issue,"},{"startTime":3338.297,"endTime":3342.063,"body":"we will devote an entire"},{"startTime":3338.297,"endTime":3342.063,"body":"lecture to the whole,"},{"startTime":3342.999,"endTime":3346.02,"body":"the challenge of methane and"},{"startTime":3342.999,"endTime":3346.02,"body":"the opportunities provided"},{"startTime":3346.02,"endTime":3347.79,"body":"by methane reductions."},{"startTime":3347.79,"endTime":3350.1,"body":"But the big picture,"},{"startTime":3350.1,"endTime":3352.53,"body":"and not to discourage anybody"},{"startTime":3350.1,"endTime":3352.53,"body":"from coming to that lecture,"},{"startTime":3352.53,"endTime":3353.79,"body":"'cause it's a very interesting one,"},{"startTime":3353.79,"endTime":3357.946,"body":"but the really big"},{"startTime":3353.79,"endTime":3357.946,"body":"picture is carbon dioxide."},{"startTime":3357.946,"endTime":3360.45,"body":"We have to appreciate"},{"startTime":3357.946,"endTime":3360.45,"body":"that the most we can do"},{"startTime":3360.45,"endTime":3363.9,"body":"on methane might cut a"},{"startTime":3360.45,"endTime":3363.9,"body":"couple of tenths of a degree"},{"startTime":3363.9,"endTime":3366.573,"body":"of warming of mid-century temperatures."},{"startTime":3367.653,"endTime":3370.65,"body":"That's a few years of fossil-fueled"},{"startTime":3367.653,"endTime":3370.65,"body":"warming at the moment."},{"startTime":3370.65,"endTime":3374.313,"body":"So it can help, but"},{"startTime":3370.65,"endTime":3374.313,"body":"this is the big picture."},{"startTime":3376.05,"endTime":3376.917,"body":"- [Audience] Thank you for the lecture."},{"startTime":3376.917,"endTime":3381.27,"body":"I was in London all through last July"},{"startTime":3381.27,"endTime":3385.89,"body":"and to me, that was the standout event"},{"startTime":3385.89,"endTime":3389.31,"body":"of the entire, in fact,"},{"startTime":3385.89,"endTime":3389.31,"body":"probably the entire decade,"},{"startTime":3389.31,"endTime":3390.99,"body":"it was terrifying."},{"startTime":3390.99,"endTime":3393.03,"body":"I dunno if you were here,"},{"startTime":3390.99,"endTime":3393.03,"body":"but it was very warm."},{"startTime":3393.03,"endTime":3395.58,"body":"It was over 40 degrees heat,"},{"startTime":3395.58,"endTime":3397.83,"body":"very dry for a very long time."},{"startTime":3397.83,"endTime":3401.25,"body":"And on, I think it was the July the 19th"},{"startTime":3401.25,"endTime":3404.455,"body":"or something that the"},{"startTime":3401.25,"endTime":3404.455,"body":"height of the temperature,"},{"startTime":3404.455,"endTime":3408.96,"body":"London Fire Brigade had its"},{"startTime":3404.455,"endTime":3408.96,"body":"busiest day since The Blitz"},{"startTime":3408.96,"endTime":3410.61,"body":"and that was when the"},{"startTime":3408.96,"endTime":3410.61,"body":"Germans were actively"},{"startTime":3410.61,"endTime":3413.61,"body":"dropping incendiary bombs on the capitol."},{"startTime":3413.61,"endTime":3416.73,"body":"So that was, nevermind the Queen dying"},{"startTime":3416.73,"endTime":3419.37,"body":"and nevermind Liz Truss and everything,"},{"startTime":3419.37,"endTime":3422.1,"body":"that seems to me the most terrifying."},{"startTime":3422.1,"endTime":3424.08,"body":"That was one of the most terrifying times"},{"startTime":3424.08,"endTime":3425.43,"body":"to be in a big city."},{"startTime":3425.43,"endTime":3430.32,"body":"And to answer your question"},{"startTime":3425.43,"endTime":3430.32,"body":"about will this government act"},{"startTime":3430.32,"endTime":3433.9,"body":"on this bill, I'm still amazed"},{"startTime":3435.479,"endTime":3437.82,"body":"that the whole government"},{"startTime":3435.479,"endTime":3437.82,"body":"machinery isn't reeling"},{"startTime":3437.82,"endTime":3439.233,"body":"from last July."},{"startTime":3440.94,"endTime":3442.953,"body":"Are you at all optimistic that this,"},{"startTime":3445.652,"endTime":3448.73,"body":"forgive me, this current"},{"startTime":3445.652,"endTime":3448.73,"body":"conservative government"},{"startTime":3448.73,"endTime":3451.68,"body":"will look back on last July just pre-Truss"},{"startTime":3451.68,"endTime":3452.607,"body":"and say, wait a minute,"},{"startTime":3452.607,"endTime":3457.113,"body":"we hit 40 degrees centigrade"},{"startTime":3452.607,"endTime":3457.113,"body":"right across Britain?"},{"startTime":3461.193,"endTime":3463.05,"body":"- Well, there's a lot in that question."},{"startTime":3463.05,"endTime":3465.48,"body":"So I'll just focus in on what,"},{"startTime":3463.05,"endTime":3465.48,"body":"you have to be an optimistic"},{"startTime":3465.48,"endTime":3466.313,"body":"in this game."},{"startTime":3467.614,"endTime":3470.16,"body":"You have to be an optimist to go to work."},{"startTime":3470.16,"endTime":3472.29,"body":"I mean, I spent my entire life worrying"},{"startTime":3472.29,"endTime":3473.123,"body":"about global warming."},{"startTime":3473.123,"endTime":3475.4,"body":"I mean, imagine what that's like."},{"startTime":3475.4,"endTime":3478.02,"body":"So yes, there are, the important thing is"},{"startTime":3478.02,"endTime":3479.67,"body":"there are solutions out there"},{"startTime":3479.67,"endTime":3481.83,"body":"and there are people who get it."},{"startTime":3481.83,"endTime":3484.11,"body":"So Liz Truss commissioned Chris Skidmore,"},{"startTime":3484.11,"endTime":3486.57,"body":"one of her first actions"},{"startTime":3484.11,"endTime":3486.57,"body":"when she came into power"},{"startTime":3486.57,"endTime":3488.13,"body":"was to commission Chris Skidmore"},{"startTime":3488.13,"endTime":3492.06,"body":"to undertake a review of"},{"startTime":3488.13,"endTime":3492.06,"body":"the UK's net-zero target."},{"startTime":3492.06,"endTime":3493.95,"body":"And I have to confess, a lot of us"},{"startTime":3493.95,"endTime":3497.04,"body":"working on climate change,"},{"startTime":3493.95,"endTime":3497.04,"body":"our hearts rather sank"},{"startTime":3497.04,"endTime":3497.873,"body":"at this point."},{"startTime":3497.873,"endTime":3499.56,"body":"'Cause we thought, oh,"},{"startTime":3497.873,"endTime":3499.56,"body":"is this just going to be"},{"startTime":3499.56,"endTime":3503.82,"body":"a sort of a route to sort of diluting"},{"startTime":3503.82,"endTime":3505.53,"body":"the whole ambition entirely"},{"startTime":3505.53,"endTime":3506.76,"body":"and perhaps that was her plan."},{"startTime":3506.76,"endTime":3509.76,"body":"If it was, then I guess"},{"startTime":3506.76,"endTime":3509.76,"body":"it didn't work out,"},{"startTime":3509.76,"endTime":3511.46,"body":"bit like some other plans as well."},{"startTime":3513.15,"endTime":3516.93,"body":"But because he actually came"},{"startTime":3513.15,"endTime":3516.93,"body":"up with a really strong review,"},{"startTime":3516.93,"endTime":3519.63,"body":"which essentially, he"},{"startTime":3516.93,"endTime":3519.63,"body":"was saying that we need"},{"startTime":3519.63,"endTime":3521.49,"body":"to go much further, much faster"},{"startTime":3521.49,"endTime":3524.61,"body":"and crucially identifying"},{"startTime":3521.49,"endTime":3524.61,"body":"issues like the need"},{"startTime":3524.61,"endTime":3526.56,"body":"for geological net zero, which are not,"},{"startTime":3526.56,"endTime":3529.77,"body":"which are nowhere in"},{"startTime":3526.56,"endTime":3529.77,"body":"legislation at the moment,"},{"startTime":3529.77,"endTime":3531.42,"body":"but it would be a two-line amendment"},{"startTime":3531.42,"endTime":3532.253,"body":"for them to acknowledge,"},{"startTime":3532.253,"endTime":3533.73,"body":"yeah, we need to get to this"},{"startTime":3533.73,"endTime":3535.7,"body":"and it would completely"},{"startTime":3533.73,"endTime":3535.7,"body":"transform the global outlook"},{"startTime":3535.7,"endTime":3537.69,"body":"in the run up to COP 28."},{"startTime":3537.69,"endTime":3541.14,"body":"So, they've got an opportunity"},{"startTime":3537.69,"endTime":3541.14,"body":"there to make history."},{"startTime":3541.14,"endTime":3542.64,"body":"- [Audience] Would you discredit"},{"startTime":3543.521,"endTime":3545.803,"body":"the carbon credit system then?"},{"startTime":3545.803,"endTime":3550.803,"body":"- I'm not the first to discredit"},{"startTime":3545.803,"endTime":3550.803,"body":"the carbon credit system."},{"startTime":3551.201,"endTime":3553.92,"body":"There's articles appearing"},{"startTime":3551.201,"endTime":3553.92,"body":"pretty much all the time"},{"startTime":3553.92,"endTime":3556.74,"body":"saying all the many problems with it."},{"startTime":3556.74,"endTime":3558.81,"body":"I guess what I would emphasize is"},{"startTime":3558.81,"endTime":3561.03,"body":"even if it worked perfectly,"},{"startTime":3561.03,"endTime":3564.66,"body":"even if everything was doing"},{"startTime":3561.03,"endTime":3564.66,"body":"what it said it was doing,"},{"startTime":3564.66,"endTime":3566.88,"body":"unless we fix this accounting problem,"},{"startTime":3566.88,"endTime":3570.24,"body":"which is a really fundamental"},{"startTime":3566.88,"endTime":3570.24,"body":"one that was sort of allowing"},{"startTime":3570.24,"endTime":3572.64,"body":"people to take credit for carbon uptake"},{"startTime":3572.64,"endTime":3576.48,"body":"that actually is happening"},{"startTime":3572.64,"endTime":3576.48,"body":"quasi-naturally anyway,"},{"startTime":3576.48,"endTime":3578.55,"body":"without them doing anything,"},{"startTime":3578.55,"endTime":3583.55,"body":"then it's never going to deliver"},{"startTime":3578.55,"endTime":3583.55,"body":"what we meant by net zero."},{"startTime":3583.83,"endTime":3585.6,"body":"Now of course, what"},{"startTime":3583.83,"endTime":3585.6,"body":"somebody means by net zero"},{"startTime":3585.6,"endTime":3586.433,"body":"is up to them."},{"startTime":3586.433,"endTime":3589.95,"body":"So, I can't tell the"},{"startTime":3586.433,"endTime":3589.95,"body":"world's governments no,"},{"startTime":3589.95,"endTime":3591.78,"body":"you should redefine net zero."},{"startTime":3591.78,"endTime":3593.97,"body":"But I can say, well, this is what we meant"},{"startTime":3593.97,"endTime":3595.914,"body":"and this is what it'll take"},{"startTime":3593.97,"endTime":3595.914,"body":"to stop global warming,"},{"startTime":3595.914,"endTime":3600.0,"body":"which is actually to"},{"startTime":3595.914,"endTime":3600.0,"body":"let nature do her thing"},{"startTime":3600.0,"endTime":3603.36,"body":"and stop dumping carbon"},{"startTime":3600.0,"endTime":3603.36,"body":"into the atmosphere"},{"startTime":3603.36,"endTime":3606.3,"body":"from fossil fuels and not"},{"startTime":3603.36,"endTime":3606.3,"body":"pretend that nature's uptakes"},{"startTime":3606.3,"endTime":3609.723,"body":"are somehow compensating for"},{"startTime":3606.3,"endTime":3609.723,"body":"our continued fossil fuel use."},{"startTime":3611.07,"endTime":3613.2,"body":"That I can do, but whether"},{"startTime":3611.07,"endTime":3613.2,"body":"the governments will listen,"},{"startTime":3613.2,"endTime":3614.043,"body":"I don't know."},{"startTime":3615.327,"endTime":3618.06,"body":"So there are simple things we can do"},{"startTime":3618.06,"endTime":3620.94,"body":"and the really simple fundamental thing"},{"startTime":3620.94,"endTime":3624.54,"body":"is to separate geological"},{"startTime":3620.94,"endTime":3624.54,"body":"from biological carbon."},{"startTime":3624.54,"endTime":3626.61,"body":"Unfortunately, very few"},{"startTime":3624.54,"endTime":3626.61,"body":"governments seem very interested"},{"startTime":3626.61,"endTime":3627.99,"body":"in this idea."},{"startTime":3627.99,"endTime":3630.0,"body":"Very few companies seem"},{"startTime":3627.99,"endTime":3630.0,"body":"very interested in this idea"},{"startTime":3630.0,"endTime":3631.842,"body":"because of course, if you are a company"},{"startTime":3631.842,"endTime":3634.89,"body":"with executives flying"},{"startTime":3631.842,"endTime":3634.89,"body":"around all over the world,"},{"startTime":3634.89,"endTime":3637.05,"body":"the last thing you want to do is say,"},{"startTime":3637.05,"endTime":3639.48,"body":"okay, there's no way"},{"startTime":3637.05,"endTime":3639.48,"body":"we can get to net zero"},{"startTime":3639.48,"endTime":3641.1,"body":"by planting trees, we're"},{"startTime":3639.48,"endTime":3641.1,"body":"actually going to have"},{"startTime":3641.1,"endTime":3642.87,"body":"to get rid of that CO2."},{"startTime":3642.87,"endTime":3645.27,"body":"It's a lot more expensive"},{"startTime":3642.87,"endTime":3645.27,"body":"to put CO2 back underground."},{"startTime":3645.27,"endTime":3646.59,"body":"It's perfectly possible,"},{"startTime":3646.59,"endTime":3647.58,"body":"but it's a lot more expensive"},{"startTime":3647.58,"endTime":3648.84,"body":"than just planting a tree somewhere."},{"startTime":3648.84,"endTime":3651.39,"body":"It's certainly much more"},{"startTime":3648.84,"endTime":3651.39,"body":"expensive than taking credit"},{"startTime":3651.39,"endTime":3653.46,"body":"for a tree that's growing anyway."},{"startTime":3653.46,"endTime":3654.86,"body":"I mean, that's really cheap."},{"startTime":3656.708,"endTime":3659.1,"body":"Okay, so, it's a big ask of the world"},{"startTime":3659.1,"endTime":3660.78,"body":"to fix this problem,"},{"startTime":3660.78,"endTime":3664.26,"body":"but unless we fix it, we're not"},{"startTime":3660.78,"endTime":3664.26,"body":"going to stop global warming."},{"startTime":3664.26,"endTime":3667.53,"body":"- Before we thank Professor"},{"startTime":3664.26,"endTime":3667.53,"body":"Allen in the usual way,"},{"startTime":3667.53,"endTime":3670.86,"body":"can I just draw your attention"},{"startTime":3667.53,"endTime":3670.86,"body":"to the Carbon Cycle Behind,"},{"startTime":3670.86,"endTime":3672.93,"body":"sorry, The Trillionth Ton of Carbon,"},{"startTime":3672.93,"endTime":3675.78,"body":"Why it Matters for Carbon"},{"startTime":3672.93,"endTime":3675.78,"body":"Change, which is on Tuesday,"},{"startTime":3675.78,"endTime":3676.8,"body":"the 18th of April."},{"startTime":3676.8,"endTime":3679.2,"body":"Tuesday, the 18th of April"},{"startTime":3676.8,"endTime":3679.2,"body":"for your diaries, please."},{"startTime":3679.2,"endTime":3682.857,"body":"Now can you join me in wishing"},{"startTime":3679.2,"endTime":3682.857,"body":"professor Allen many thanks."},{"startTime":3682.857,"endTime":3685.69,"body":"(audience claps)"}]}