Azara Blog: Humans and the Global Carbon Cycle: A Faustian Bargain

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Date published: 2007/02/15

There was a talk this afternoon at New Hall by Berrien Moore, from the Institute for the study of Earth, Oceans and Space at the University of New Hampshire, about "Humans and the Global Carbon Cycle: A Faustian Bargain" (part of the Environment on the Edge series). He showed some standard slides that always come up in the climate change debate, with numbers attached. For example, with the carbon cycle, the atmosphere has around 750 gigatonnes of carbon in it, humans produce about 5.5 (well now more like 7) gigatonnes of carbon per year, etc. He showed the standard CO2 concentrations measured by David Keeling from 1958-2005 at the Mauna Loa observatory (it's an almost straight line going upwards when you average out the small, mainly annual, fluctuations). He showed some of the standard slides of temperature over the last thousand and more years. He showed some of the standard slides about the Arctic ice disappearing.

Of course all the evidence points to fossil fuel burning as leading to the increased atmospheric CO2, and the problem is not the CO2 per se, but the consequences of having so much in the atmosphere, which usually goes under the name of global warming. So the talk was pretty much the usual litany.

He did mention that in the most recent IPCC reports, they had a prediction of a rise in average surface temperature of between 1.4 and 5.8 degrees C by 2100, and that around half of that uncertainty was down to not knowing what future carbon emissions would be like, and about half was down to model uncertainty, which is interesting.

Of course there are a lot of feedback systems in the carbon cycle. Presumably many of them are negative, because our climate is fairly stable. But the big worries for him were the potential positive feedback mechanisms. For example, the oceans are estimated to store around 38100 gigatonnes of carbon, which dwarfs the 750 in the atmosphere. As temperature rises, the solubility of CO2 in water decreases. So that by itself is of course a possible serious positive feedback mechanism.

His bottom line, like most climate scientists, is that even if we stabilised CO2 emissions at (say) 2000 levels, the atmospheric concentration would continue to rise. The only way to avoid that is to actually reduce emission levels. Well, most people seem to recognise that, it's just a question of how one goes about that.

In the question and answer session his opinions were fleshed out a bit more. For example, he claimed he was not so worried about the increase in temperature per se than in the effect on water (e.g. desertification, etc.) (After all, as he joked, in the US, Arizona is attracting many more new citizens than New England. So many people seem to prefer it hotter. Well, that is because they can air condition away the heat in summer.)

Someone asked about whether people would do anything before it was too late, because the worst consequences would not happen before it was too late to prevent it getting even worse. His take on that was that people had to do something, which of course is then down to political leadership. As he said, knowledge about what is going to happen is not the rate-limiting step. (That is one of the problems with the current debate. Far too much time is spent on trying to "prove" that humans are responsible for the increase in temperature. Far more time should be spent on trying to figure out what to do about it.)

Someone asked about nuclear power and he said he would seriously consider using it, even though he was once opposed to one in his backyard. One of the standard lines of people who are now considering nuclear power is that France, which gets much of its electricity from nuclear, has one of the lowest emissions per capita of any developed nation (about a third of the US). Of course the zealots (and Cambridge is full of them) would have nothing to do with nuclear power.

Someone asked about population. We are now 6 billion and we are allegedly headed for 9 billion by mid-century. He said that someone had recently quipped to him that the cheapest way to reduce carbon emissions was to reduce the population. And of course this is true, but it is also the one thing that most people refuse to address. Many European governments practically bribe their citizens to have as many children as possible. Of course most of the population increase is happening in the poor world, but they are also responsible for far fewer emissions per capita.

Someone asked about carbon credits (e.g. you pay someone to plant a few trees when you fly). He said he was not totally opposed to them (since in theory they reduce the carbon in the atmosphere) but he was philosophically queasy about them. (It seems like too good a thing. You can continue with life as normal as long as you can afford to pay a tax associated with it.) He said everyone should take personal responsibility for their carbon emissions. Well that is a bit of a meaningless statement. Everybody who was in the room to hear the lecture is far, far richer than the average citizen of the world and so is responsible (directly or indirectly) for far, far more emissions. And although lots of the academic middle class like to wring their hands on the subject, in truth the best way to reduce your carbon emissions is to become poor (well, and not have children), and none of them are volunteering to do that.

Someone asked whether we would have to go back to a pre-industrial age. His take on that was no. Somehow we would figure out how to reduce the carbon in the atmosphere. And we would even be better off than now when we did. Well, that sounds like a bit too much wishful thinking. And it would be a big disaster for so-called environmentalists if mankind found a cheapish, cleanish source of energy, because it would mean we were even more capable than ever of changing the environment as we saw fit.

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