COP15 – Dec 8, 2009 – IPCC Session

Today, the IPCC organized a side event on “IPCC Findings and Activities and their Relevance for the UNFCCC Process,” summarizing its AR4 findings (AR = Assessment Report) and offering a forward look on AR5.

In his introduction, the IPCC Chair R.K. Pachauri offered an overview of the IPCC process to reach at that what I would call our “best available science” (BAS) today. To build up AR4, 450 scientists participated as lead authors, working in teams, the work of which has been subject to peer (more than 2.500 scientists collaborated) and governmental expert reviews. The IPCC uses reliable data sets gathered from many sources that corroborate one another. Its procedures are very reliable, robust and transparent. Recently, the reliability of the IPCC has been questioned because of the publication of private e-mail correspondence obtained by malicious hacking into the servers of the East Anglia Climate Research Unit. Climate skeptics and even countries such as Saudi Arabia have made use of the exasperation of scientists with those who contest anthropogenic global warming to spread doubt about the seriousness of IPCC reports. I felt somewhat of that anger, when it became clear that all the questions addressed to R.K. Pachauri – mostly by anglo-saxon journalists – concerned these e-mails. But, of course, if I say that these journalists should know better and focus on the real issues at stake, that in press conferences their questions should be ignored when they have been asked over and over again, then I run the risk of being considered intolerant and in danger of obscuring issues. I admire the patience with which R.K. Pachauri answered these questions and observations – that in itself is worth a Nobel Prize.

Thanks to God, the rest of the side event was devoted to the real issues at stake. Scientists presented the issues at stake in the three Work Groups (WG) of AR4, and their outlook on AR5.

Thomas Stocker, co-chair of WG1 (the physical science basis of climate change), emphasized and illustrated three important results of AR4 WG1: (a) warming in the climate system is unequivocal; (b) most of the observed increase in temperature is very likely due to an increase in GHG (greenhouse gas) concentrations in the atmosphere; (c) continued GHG emissions will lead to changes that would very likely be larger than those observed today. For AR5, Stocker points to three observations and three projections: (O1) CO2 presence in the atmosphere reaches higher levels and its increase is more rapid than ever over the past 1000 years; (O2) the extensive thinning of ice surface on the margins of Greenland and Antarctica; (03) the persistent sea-level rise consistent with earlier estimates; (P1) the rapid loss of arctic sea ice (depending on the models used, the arctic sea will be ice free sometime between 2030 and 2060); (P2) the long-term commitment and irreversibility of the CO2 perturbation (it will take hundreds of years before CO2 levels in the atmosphere will diminish); (P3) geo-engineering could cause abrupt climate changes, but there is a “termination problem” inherent to all geo-engineering (if we stop the geo-engineering process, global climate quickly returns to an equilibrium near to what would have been the case without the geo-engineering). Stocker concludes that there is good reason to stand behind the scientific results presented in AR4, that we experience unprecedented changes in the climate system, that there is widespread melting of the ice margins, that CO2 remains in the atmosphere for very long periods and leads to changes in climate and in ocean chemistry, and that geo-engineering is inherently problematic. These issues will be addressed in AR5 WG1.

Charles Field presented the activities of WG2 (impacts, adaptation and vulnerability), stressing that AR4 presented a vast range of observed changes and impacts as well as of projected future impacts (the magnitude of which depends on the models used; extreme events are possible as well). He observed that many stressors are important as far as impacts are concerned. Mitigation can help to delay, avoid or reduce impacts, while adaptation can address vulnerabilities. AR5 will concentrate on common frameworks for mitigation, adaptation and impacts; it will broaden the range of impacts and study the connections between climate change and development, as well as between climate science and climate impacts; it will take into account a new generation of models and pay due attention to regional aspects and to ocean impacts. Climate change is occurring: what information is needed for good policy decisions?

Vicente Barros, also speaking in the area of AR5 WG2, introduced a special report on managing the risks of extreme events and disasters to advance climate change adaptation, a report that will be published in 2011 and that will focus on the intersection of three concerns: (a) vulnerabilities; (b) the frequency, intensity and duration of extreme events; (c) the tools available for disaster risk reduction and climate change adaptability.

As to WG3 (climate change mitigation), Youba Sokona pointed out that global anthropogenic GHG emissions, especially CO2 emissions, are still growing. Contributing factors to this continuing increase are population growth, income increase per capita, carbon intensity and energy intensity. The stabilization of GHG concentrations in the atmosphere is, from a scientific point of view, urgent, and technological advances and transfers will be important to attain this. All sectors and regions will have to contribute.

The question session afterwards highlighted the need to take into account ocean factors, e.g. acidification, as well as time and regional scales, whereby a distinction will be made between near-time predictability and long-term climate change.

It is clear that the work for AR5 is well under way and that it will produce a wider array of models and frameworks to unfold a reality that comes forward in ever increasing complexity. The methods will also allow for improved regional focus, which will allow improved adaptation planning. Although a lot of mist was created by continuing questions on the hacking of personal e-mails, it is clear that the IPCC aims at maintaining its focus on essential matters and with increasing scientific sharpness. One can only applaud that. I feel the deep commitment of these scientists to provide reliable and clear material for good and crucial policy decision making. This was a very refreshing session.

The IPCC provides our best available science today (BAS). Let us keep these scientists in high esteem!


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