Climate Model Democracy
12 hours ago Andy May 52 Comments
By Andy May
In my last post, I explained how the IPCC attempts to use climate models to show humans have caused the recent global warming. Models are useful for testing scientific ideas, but they are not proof an idea is correct unless they successfully and accurately predict future events. See the story of Arthur Eddington’s test of Einstein’s theory of relativity here. In the computer modeling world, a world I worked in for 42 years, choosing one model, that matches observations best, is normal best practice. I have not seen a good explanation for why CMIP5 and CMIP6 produce ensemble model means. It seems to be a political solution to a scientific problem. This is addressed in AR6 in Chapter 1,[1] where they refer to averaging multiple models, without considering their accuracy or mutual independence, as “model democracy.” It is unclear if they are being sarcastic.
Figure 1. John Christy’s comparison of the CMIP6 models, their ensemble mean (red and yellow boxes), and two observation datasets in green. The light green is a weather balloon dataset, and the dark green is a weather reanalysis dataset. Each dataset is for the tropical mid-troposphere from 300 to 200 hPa, roughly 10 to 12 km in altitude, the so-called tropical model “hot spot.” Source: Dr. John Christy, the graph is after a presentation Christy gave to the Irish Climate Science Forum on January 22, 2021.
Figure 1 shows the CMIP6 (IPCC, 2021) or the IPCC AR6 models, their mean in yellow and red boxes, and observations in green. In this region of the tropical troposphere, often called the climate model “hot spot,” climate models have always overestimated warming.
https://wattsupwiththat.com/2022/03/11/climate-model-democracy/
