Het uur der waarheid nadert voor het VN-klimaatpanel
In het licht van recente publicaties over een lagere klimaatgevoeligheid zou het IPCC-rapport dat binnenkort wordt gepubliceerd eigenlijk helemaal overnieuw moeten worden geschreven. Maar zal dat ook gebeuren?
Onder de titel, 'The IPCC AR5 Is in Real Trouble', schreven Paul C. "Chip" Knappenberger and Patrick J. Michaels:
The United Nations Intergovernmental Panel on Climate Change (IPCC) is in the midst of finishing its Fifth Assessment Report (AR5) on the topic. Based on a series of content leaks, it seems as if the AR5 has so much internal inconsistency that releasing it in its current form will be a major fiasco.
The central issue of climate change science is the earths equilibrium climate sensitivity (ECS)that is, how much the earths average surface temperature will increase as a result of a doubling the atmospheric carbon dioxide concentration.
New and mutually consistent re-assessments of this important parameter are appearing in the scientific literature faster than the slow and arduous IPCC assessment process can digest them (presuming it even wants togiven that they are making the current AR5 look pretty bad). Further, even if the IPCC is able to do an adequate job of assimilating this evolving and quite convincing science, the vast majority of the rest of the IPCCs report will also have to be changed as it is highly dependent on the magnitude of the climate sensitivity. By now, though, its too late in the game (the final report is due out in early 2014)the cows have all left the IPCCs barn on these subjects and its too late to round them all up and rebrand them. ...
According to The Economist, which claims to have seen the most recent draft of the IPCCs AR5, the IPCCs assessment of climate sensitivity has now been altered. Here is how The Economist describes what is in the new IPCC draft concerning the equilibrium climate sensitivity:
Both the 2007 IPCC report and a previous draft of the new assessment reflected earlier views on the matter by saying that the standard measure of climate sensitivity (the likely rise in equilibrium temperature in response to a doubling of CO2 concentration) was between 2°C and 4.5°C, with 3°C the most probable figure. In the new draft, the lower end of the range has been reduced to 1.5°C and the most likely figure has been scrapped. That seems to reflect a growing sense that climate sensitivity may have been overestimated in the past and that the science is too uncertain to justify a single estimate of future rises.
If this is true, the combination of the IPCC lowering the low end of the range of possible climate sensitivity values and the IPCC deciding not to provide its assessment of the most likely value strongly suggests that the average climate model sensitivity of 3.4°C is even further removed from the science on the topic and less justifiable. Just how far removed the climate models really are is kept under wraps by the IPCC by its no longer supplying a most likely value. If the most likely value were to be assessed at 2.5°C, then the climate model average would be 36% too high compared to the science. If the most likely value were to be 2.0°C, then the model average climate sensitivity would be some 70% too high.
Because, as the IPCC admits, the change in many other climate variables scales with the increase in global-mean surface temperature, the climate impacts derived from the model projections (which essentially is what the IPCC is all about) are also (substantially) too high.
The IPCC has three options:
1.Round-file the entire AR5 as it now stands and start again.
2.Release the current AR5 with a statement that indicates that all the climate change and impacts described within are likely overestimated by around 50%, or
3.Do nothing and mislead policymakers and the rest of the world. Were betting on door number 3.
Scary thought.
Lees verder hier.
Ik ben er niet zeker van of de auteurs gelijk krijgen. In het licht van eerdere onregelmatigheden kan het IPCC er niet meer zeker van zijn dat het met dezelfde welwillendheid en goedgelovigheid door de politiek, media en publiek wordt behandeld als eerder het geval is geweest. Zouden zij inderdaad voor optie 3 kiezen dan zouden zij zich zeer ongeloofwaardig maken. Zó dom zullen ze toch niet zijn?
Voor mijn eerdere DDS-bijdragen, zie hier.
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