2 00:00:10,050 --> 00:00:14,270 They can measure how much CO2 is 3 00:00:14,270 --> 00:00:18,010 invading the oceans by a variety of different techniques. 4 00:00:18,010 --> 00:00:21,500 You can just go out and measure the concentration of CO2 and, 5 00:00:21,500 --> 00:00:24,980 of course, there's a lot of dissolved carbon already in the water. 6 00:00:24,980 --> 00:00:29,910 It's a tricky question to distinguish the tiny 7 00:00:29,910 --> 00:00:35,240 fraction that is new carbon, that invaded the ocean from fossil 8 00:00:35,240 --> 00:00:37,460 fuel combustion, but it can be done. 9 00:00:37,460 --> 00:00:42,730 Or there is a very clever method that I wanted to show you that involves measuring 10 00:00:42,730 --> 00:00:48,480 simultaneously changes in atmospheric CO2 and also oxygen. 11 00:00:48,480 --> 00:00:54,850 When you burn fossil fuel, that's like respiration, it consumes oxygen 12 00:00:54,850 --> 00:01:02,250 and so the CO2 concentration goes up and the oxygen concentration goes down. 14 00:01:02,250 --> 00:01:05,390 Then there are two different possible fates 15 00:01:05,390 --> 00:01:08,220 of that CO2 that we're trying to distinguish here. 16 00:01:08,220 --> 00:01:14,570 One is that it could get taken up by trees on land 17 00:01:14,570 --> 00:01:20,750 by some photosynthesis. When that happens it releases oxygen. 18 00:01:20,750 --> 00:01:23,890 The other possibility is that it can just dissolve 19 00:01:23,890 --> 00:01:26,200 in water and then it does this buffer chemistry, but 20 00:01:26,200 --> 00:01:32,200 it doesn't immediately get turned into photosynthesis. It doesn't produce oxygen. 21 00:01:32,200 --> 00:01:36,440 If you compare the rate at which CO2 is 22 00:01:36,440 --> 00:01:41,250 rising with the rate at which oxygen is falling you can 23 00:01:41,250 --> 00:01:43,490 decide how much of the carbon is going 24 00:01:43,490 --> 00:01:47,990 into the land biosphere, verses how much is into the ocean. 25 00:01:47,990 --> 00:01:51,586 The bottom line is about 26 00:01:51,586 --> 00:01:54,120 50:50 (equal proportions). 27 00:01:54,120 --> 00:01:59,790 There's about two gigatons a year going into the oceans. 28 00:01:59,790 --> 00:02:02,470 And they can measure that by multiple methods and 29 00:02:02,470 --> 00:02:04,430 they get the same answer by the different methods. 30 00:02:04,430 --> 00:02:06,380 We have confidence in that. 31 00:02:06,380 --> 00:02:10,330 And then, just by difference by balancing the budget, there has to be 32 00:02:15,130 --> 00:02:21,170 an uptake going into the land of about three gigatons a year of carbon. 33 00:02:21,170 --> 00:02:23,340 And this is dicier because we don't know where that is. 34 00:02:23,340 --> 00:02:25,520 We're still trying to figure out even though it's a massive 35 00:02:25,520 --> 00:02:29,500 amount of stuff but it's just harder to find on land. 36 00:02:29,500 --> 00:02:33,119 Anyway the bottom line is that to a large extent the ocean 37 00:02:33,119 --> 00:02:37,220 and the land are helping us out by absorbing fossil fuel CO2.