Seeking responses to article claiming many climate models' climate sensitivities are too high.
Brian Cady
https://phys.org/news/2026-02-rethinking-climate-natural-variability-solar.html
https://www.sciencedirect.com/science/article/pii/S1342937X25001273
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Michael MacCracken
Dear Brian--On the URL commenting on climate model results, it seems not mentioned at all about the uncertainties in the reconstruction of the details of the Earth's climatic history during the Holocene. As just one example, regarding the apparent warm period in the late 1930s-early 1940s. If you look in detail, the warm years are pretty much all during World War II and pretty much for the ocean measurements and not over the land. There are all sorts of reasons why biases arose during World War II (different set of ships from different countries, different routes, different measurement techniques, not wanting to reveal positions of ships, etc.) that have been hard to figure out--and this unfortunate bias has been made into the basis of a supposed cycle as it seems by pure coincidence to be about the same time the small increase in solar output peaked--if the little change in solar radiation indeed caused the warming, the climate sensitivity would have to be higher than the models project.
Going back further in time, much of the basis for the cycles comes from the Mediterranean region where measurement were greatest and it is not at all clear they represent global cycles. There have also been changes in the orbital parameters (shape of the orbit, tilt, time of year of closest approach to the Sun) that are just a redistribution of solar radiation by season and latitude that are not accounted for as causes (the IPCC global forcing table does not consider these factors as only goes about 150 years, but it was thee changes over longer times that drove global glacial-interglacial cycling so they matter over the longer term considered in the paper.
There are other issues as well, such as explanations for the cycles rather than asserting cycles without causes so quite possibly just happenstance correlations. This is the type of analysis done a lot in the decades before the mathematical capabilities of models forced analyses to be quantitatively consistent across forcings rather than, at least in the article, being pretty much qualitative and failing to really consider the uncertainties in the Holocene record (both of the forcings and the outcomes).
Best, Mike MacCracken
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