Tuesday, 8 December

The Copenhagen meeting started. It is difficult to predict its outcome. While browsing through the COP15 web page, I was interested in reading what is the definition of an good outcome for Yvo de Boer, executive secretary of the UN Framework Convention on Climate Change (UNFCCC). Yvo de Boer is hoping that the Conference will bring clarity in the following four essentials:

1. How much are the industrialized countries willing to reduce their emissions of greenhouse gases?
2. How much are major developing countries such as China and India willing to do to limit the growth of their emissions?
3. How is the help needed by developing countries to engage in reducing their emissions and adapting to the impacts of climate change going to be financed?
4. How is that money going to be managed?

De Boer feels confident that President Barack Obama can successfully engage China and India and convince them to sign the next treaty.

Speaking of climate change, I think all sensible people agree that there is uncertainty in future predictions. However, it is important to realise that the uncertainty means it could be better or it could be worse. A new article to be published in Nature Geoscience concludes that the long-term effect of an increase in atmospheric CO2 on global temperatures could be about 45% more than the short-term effects previously considered in past IPCC modelling. The paper by Lunt at al reports on the results of a study which modelled the temperatures in a mid-Pliocene period (about 3.3 - 3 million years ago). They picked this period because:

• the atmospheric CO2 concentrations at about 400 PPM were higher than the pre-industrial values; and
• there is good proxy data about the temperatures in the same period.

The modelling included the feedback from variable vegetation and ice covers but not aerosols and atmoshperic chemistry. They compared the modelled mid-Pliocene temperatures against the temperature estimates based on a combination of faunal analysis of planktic foraminifera, Mg/Ca and alkenones. I am not exactly sure what these things are but they sound like examination of past fossil layers and proper references are given to the sources where the estimates are made. The comparison between the modelled temperatures and the measured (by proxy) temperatures is pretty good (about 0.15 ^oC). The model calculates the global temperature increase that would be caused by a jump in the CO2 levels from 280 to 400 ppmv and finds it as 2.3 oC. The shorter-term feedback modelling used in IPCC scenarios predicted only 1.6 oC. Hence my starting comment that the uncertainty means uncertainty both ways. According to this paper, the long-term global temperatures for a particular CO2 emission scenario could be as high as 45% above the most-likely scenario from past IPCC models. Food for thought.

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