Connecting the SST Pattern Problem and the Hot Model Problem

In the equatorial and subtropical east Pacific Ocean, strong ocean-atmosphere coupling results in large-amplitude interannual variability. Recent literature debates whether climate models reproduce observed short and long-term surface temperature trends in this region. We reconcile the debate by reevaluating a large range of trends in initial condition ensembles of 15 climate models. We confirm that models fail to reproduce long-term trends, but also find that many models do not reproduce the observed decadal-scale swings in the East to West gradient of the equatorial Pacific. Models with high climate sensitivity are less likely to reproduce observed decadal-scale swings than models with a modest climate sensitivity, possibly due to an incorrect balance of cloud feedbacks driven by changing inversion strength versus surface warming. Our findings suggest that two not well understood problems of the current generation of climate models are connected and we highlight the need to increase understanding of decadal-scale variability.

Automated summary

This study evaluates a range of trends in climate models and finds that they fail to accurately reproduce the surface temperature trends and observed decadal-scale swings in the equatorial and subtropical east Pacific Ocean. Models with high climate sensitivity are less likely to reproduce the observed swings, potentially due to an incorrect balance of cloud feedbacks. These findings highlight the need to increase understanding of decadal-scale variability.