There's a swedish article over at energy bulletin worth having a look at:http://www.energybulletin.net/29845.html. In it, Kjell Aleklett of Uppsala University argues that we simply don't have enough carbon to burn to bring about the worst case scenarios of global warming, and that the energy crisis will prevent the outside temperature increases.
I know I'll be watching the responses to this piece, because I'm certainly no climate scientist. In many ways I'd be thrilled to see that Aleklett was correct - I think dealing with peak oil but not with global warming is a much more manageable situation.
On the other hand, I have my doubts, particularly because Aleklett's arguments are based on the IPCC numbers, which are terrifically conservative. The thing is, the Potsdam Institute estimates that our best chance of keeping temperatures below the critical 2 degree threshold means keeping the parts per million of atmospheric carbon below 440 (at which point have 2 out of 3 odds - not that great - of maintaining the lower temperatures). But the IPCC estimate is that we are now at 469 ppm - that is, in order to stabilize the climate we have to lower the atmospheric carbon levels dramatically, because we're already over the line. The IPCC, being a political document, holds the 500 ppm line, but the facts don't back this up. At 500 ppm, we have only a 30% chance of avoiding the critical 2 degrees of warming.
Now Aleklett is right that we probably do have to hold atmospheric carbon levels for some time in order to have a dramatic warming effect, but I think his article, because of its focus on the IPCC, underestimates the time we need to be burning carbon. Even if the direst predictions are right - that oil is past peak, natural gas is about to peak and coal will do so within the next 10-15 years, that means at least another decade of heavy carbon energy use, including a great deal of coal. While it is true that the IPCC models show long term human carbon contributions, what may matter most is simply having enough carbon long enough to get the earth into an irrevocable cycle. In fact, emissions rates are rising much faster than the IPCC report indicates - a paper published today by scientists at the Global Carbon Project shows that the rate of emissions increase tripled between 2000 and 2004 http://www.theage.com.au/articles/2007/05/22/1179601340054.html. We're burning more carbon, faster, than the IPCC or anyone expected, which means that the IPCC models are dangerously conservative, and Aleklett's analysis is impacted by that.
Now the reason we're trying to hold things below the 2 degree mark is this - climate change has an ugly tendency to accellerate on its own, but most of the things that cause it to snowball are left out of the IPCC report because they are controversial. No one knows exactly how much methane the seas might release, or the soils. So for the most part, the IPCC models leave out the worst possible consequences - that we might already or soon be past the point of no return, at which the earth simply takes over. By setting his baseline against the very conservative IPCC report, which includes comparatively few of the factors that might cause accelleration, Aleklett ignores the reality that we may get to the worst case scenarios even given peak oil.
Now were these factors merely speculative, there would be a case for Aleklett's arguments. But while the exact impact of these factors is not known, most of them represent *observed* phenomena - not speculation about what might happen, but things that are already occurring. That is, this week a report was released that showed that the southern oceans are now saturated and ceasing to absorb carbon http://www.theglobeandmail.com/servlet/story/RTGAM.20070517.wocean0517/BNStory/Science/home
Last year, British scientists began to observe soils releasing their carbon, and artic researches spotted bubbles of methane newly released by northern seas. And of course, the rainforests are already heating up, catching fire and burning - tens of thousands of acres have done so in the last year.
Is Aleklett's analysis possible? It is. Is it complete - I don't think so. For example, none of these take into account the issue of global dimming, which by itself might be enough to push the climate over the edge. Nobel winning professor Paul Creutzen estimates that if global dimming - the particulate emissions that cut the sun's impact on the earth - were taken out, temperature rises would be between 7 and 10 - on the apocalyptic end of things. Global dimming is a particularly important factor if Aleklett is right, because those particulate emissions that are keeping the sun from heating up the planet even more are also products of fossil energy consumption - that is, as we are priced out of fossil energy, or begin to radically conserve, the sun's heating effect is likely to increase dramatically. Even demand destruction is likely to accellerate global warming - one of those rock and a hard places things.
What Aleklett's essay seems to me to imply is something that worries me a great deal - we may have time to up our emissions, but not enough time to get them down. Think about it this way - let us say that Aleklett is correct, and that all three major fossil sources will have peaked by the end of the next decade, and energy prices will get off their undulating plateaus shortly and begin to rise even more radically. What does that do to the world economy? What does that do to our daily lives? And how likely is it that we will then begin a major build out of renewable energy, infrastructure changes, etc...?
The thing is, switching over, even to a very limited and low energy society (one which is largely human powered), much less the "we can have it all with renewables fantasy that most people cling to" - is a hugely energy and money intensive project, much more so that simply going on the way we are. And it depends on our basic ability to keep the economic balls up in the air - that is, having enough capital to invest in even basic public transport, letting our hospitals run on renewables and reinsulating our houses depends on the economy going forward. And right now, our current, debt based economy going forward depends on the economy continuing to grow, which requires a ton of energy.
It is much less energy and capital intensive to simply go on the way we are, letting the market gradually price people out of things like gas and electricity. So if we're as close to the end, there's a good chance that we can keep things going as long as we don't try and mess with it too much, but we'll have a tough time starting big projects - that is, we have the ability to keep burning the carbon, but not the ability to stop burning it in a productive way.
Aleklett is absolutely right that an analysis of the impact of peak oil on global warming is absolutely necessary, and reliable energy numbers are necessary. I have my doubts that he's right that peak oil will stave off global warming, though.