Climate Code Red: IPCC: Separating the science from the politics?https://www.climatecodered.org/2023/03/ipcc-separating-science-from-politics.htmlA key feature of IPCC reports on the physical science has been to elevate climate models to the centre of the process, whilst relegating the bigger picture understandings that come from climate history (paleoclimatology) to a secondary position. Paleoclimatology teaches that in the long run each one degree of warming will raise the oceans by 10-20 metres. Models, unable to properly include cryosphere processes, suggest sea-rises to 2100 so small that the projections are not credible, a process of scientific reticence highlighted by NASA science chief James Hansen as far back as 2007.
Current climate models are not capturing all the risks, such as the stalling of the Gulf Stream, polar ice melt and the uptick in extreme weather events. Prof. Michael Mann says that “when it comes to certain important consequences of the warming, including ice sheet collapse, sea level rise, and the rise in extreme weather events, the [IPCC] reports in my view have been overly conservative, in substantial part because of processes that are imperfectly represented in the models.”
Another fundamental problem is the approach to risk. IPCC carbon budgets regularly include risks of failure (overshooting the target) of 33% or 50%, that is, a one-in-two or one-in-three risk of failure. Thus a 2-degree carbon budget with a 50% chance actually has a 10% risk of ending up with 4 degrees of warming, which is incompatible with the maintenance of human civilisation.
These are risks of failure that no government or person would agree to in any other aspect of life — whether it be buildings and bridges, safety fences or car seats — where acceptable failure rates are tiny fractions of one per cent