Fingerprinting and climate prediction uncertainty

In his new paper, statistician William M Briggs surveys the field of climate attribution studies, in which changes in the weather are blamed on humankind. In particular, he looks at the recent pronouncements on that subject by the Intergovernmental Panel on Climate Change in its Sixth Assessment Report.

Briggs conclusion is that climate scientists are far too confident in their conclusions:

Earlier this year, the economist Ross McKitrick published a new paper about an important methodology used in attributing changes in weather events to mankind. McKitrick observed that the so-called "optimal fingerprinting" methodology, which has been used in numerous studies and has been behind dozens of newspaper headlines about mankind's influence on the atmosphere, was statistically erroneous. The implications of the findings are therefore potentially profound.

The restrictions imposed around the world during the Covid pandemic saw an overall decline in emissions of CO2 of 5.6%.

So why hasn't that fall been echoed in atmospheric concentrations - which are the subject of this latest data from the WMO?

There are a number of factors involved.

Around half of emissions from human activity are taken up by trees, lands and oceans. But the absorbing ability of these sinks can vary hugely, depending on temperatures, rainfall and other factors.