Remember I was going to not blog for two and a half weeks - wow, that time passed quickly. It seemed more like 2 1/2 days. I did say it was a compulsion. But I'm still on vacation, I swear
I do, however, feel obligated to discuss the question of whether or not irrevocable climate change is upon us, because of the debunking RealClimate gave of Tim Flannery's analysis here: http://www.realclimate.org/index.php/archives/2007/10/co2-equivalents/.
Now I should say that I take Flannery's analysis far less seriously than the article I posted a few days ago, that includes the climate model by Weaver and U Victoria here:
http://environment.newscientist.com/article/dn12775-zero-emissions-needed-to-avert-dangerous-warming.html. But it is also worth observing that Flannery is not the first person to come to the conclusion that we have already passed the tipping point or will do so in the next few years. While RealClimate is right to point out the relevant excluded distinctions, I'm inclined to believe that Flannery and Weaver are both right.
Why? Because Flannery's analysis relies on data that the IPCC did not have at the time that its report was compiled. It is not the case that Flannery's analysis simply excludes negative factors and includes positive ones - his analysis derives in part from the fact that emissions rates are rising far faster than the IPCC ever predicted - than anyone ever predicted. And that factor is enormously significant, and one of the reasons I think RealClimate's analysis is insufficient. It may turn out that Flannery is wrong, when all the reports are made available, but their flat statement that this is wrong is, I think, far too quick - we are dealing with subjective data analyses, and I don't think anyone knows that for certain. As one of the commentators on the RealClimate site observes, the negative factors tend to dissipate quickly, while the positive factors tend to linger in the atmosphere, continuing to warm the planet longer than the negatives cool it.
Moreover, when you reduce the positive (heating) emissions, you also reduce the compensatory (negative) emissions, and get more total warming. This is the factor (essentially left out of the IPCC analysis) of Global Dimming, which potentially doubles or triples the heat factor of our emissions. It is Global Dimming that has, most likely, prevented us from reaching 2 degrees already. Flannery's analysis follows the analysis of other major studies, including ones at the Hadley Center and the British Panel on climate change - it is by no means as clear to me as it seems to be to the RealClimate folks that we have an absolute consensus that we should include all the negative factors - or rather, that we fully understand what an absolute total of 450 ppm greenhouse gases, *with* the negative factors will do.
Remember, the 450-550 number is not something for which there is a uniform scientific consensus. At best, the lower number give us a 2 out of 3 shot of not hitting the critical 2 degree scenario. There is no scientific consensus that 550 ppm is acceptable - that is a political number, not a scientific one.
But I personally don't take Flannery's or Weaver's analysis as the final word, but as tools in the aggregate data that is coming out that demonstrate that climate change is occurring far faster and harder than anyone ever thought. Their analysis seems, in general, to better follow all the other bits of data that are flowing in so rapidly. The reality is that if you follow the IPCC's lines of analysis, the arctic ice shouldn't be melting at the present rate. If you follow their analysis, the seas shouldn't have started releasing methane. If you follow their analysis the Greenland ice sheet shouldn't be showing signs of early destabilization. All of these things shouldn't happen for between 40 and 100 years - but, in fact, they are happening now.
Whatever your analysis of the data as a whole, it seems clear that the IPCC figures are simply inadequate to the reality of climate change. This is not a slur on the IPCC scientists - the world as a whole, scientist and layperson alike, are struggling to catch up with our own impact. Whether Flannery is correct or not, the reality is that we have to deal with some really inconvenient truths of our own. They are:
1. Climate Change is striking us more immediately than we ever expected. We are probably closer to a tipping point, if we are not there, than anyone knows.
2. We are flying by the seat of our pants here, and no one analyst really knows what's going on - the most exact tools we have right now are not scientific, but ethical - that is, we cannot risk killing billions of people simply to serve our own convenience.
3. In a sense it doesn't really matter - we're not right now doing much of anything. The odds are good that the rich world will continue its practices for some time.
4. But, of course it does matter enormously. It isn't just the case that at 2 degrees, we're committed and there's nothing we can do. The effects of 450 ppm are very different than 600 or 700ppm. We have to stop making personal and industrial emissions. And that means changing - fast and hard.
Sharon, going back on vacation for real this time...probably