Newest climate models shouldn’t raise future warming projections

Enlarge (credit: Brunner et al./ESD)

One notable storyline in the climate system over the past year or two has been the effort to make sense of the latest generation of climate models. In service of the next Intergovernmental Panel on Climate Change (IPCC) report, the world's climate models have submitted their simulations to the latest database, known as CMIP6. These submissions showed that updates to a number of models had made them more sensitive to greenhouse gases, which means they project greater amounts of future warming.

Apart from diagnosing the behavior responsible for that change, climate scientists have also wrestled with the implications. Should we be alarmed by the results, or are they outliers? Climate models are only one tool among many for estimating Earth's true climate sensitivity," so their behavior has to be considered in the full context of all the other evidence.

For a number of reasons, research is converging on the idea that the high temperature projections are outliers; these hotter models seem to be too hot. That will present a challenge for the scientists working on the next IPCC report: how much influence should these outliers have on projections of future warming?

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