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Feb 24, 2021 12:00 pm
Climate models fail to simulate observed tropical warming patterns, weakening constraints on future warming.
The pattern of changes in Sea Surface Temperatures (SSTs) over recent decades has been marked by
enhanced warming in the western equatorial Pacific and cooling in the eastern Pacific and Southern
Ocean. Current state-of-the-art coupled numerical climate models fail to reproduce this observed pattern.
Due to this discrepancy in SST patterns, observations lie outside simulated climate change across several
key metrics – critically among them the net radiative feedback. Our analysis shows that this discrepancy
in SST patterns could account for the inability of high climate sensitivity CMIP6 coupled models to
reproduce historical warming.
If the bias is due to either a transient in the forced response or natural variability, then high long-term
equilibrium climate sensitivity cannot be discounted using emergent constraints based on recent warming
trends. It remains an open question whether the problem in the coupled models lies with a bias in the
forced response or insufficient natural variability.