Tug of war on summertime circulation response to global warming

Confidence in state-of-the-art climate model projections of the response to global warming is often quantified by model consensus. During summertime, monsoons and subtropical anticyclones shape regional circulation and precipitation patterns across the globe. The multi-model-mean response to global warming for the Asian monsoon cyclone, Pacific anticyclone and jet stream is weak and not robust across the models. Here we show the weak response is due to a tug of war involving opposite land-sea thermal contrasts and circulation responses to direct radiative forcing and indirect sea surface temperature warming that can be understood using the seasonal response to solar insolation, quasi-equilibrium thermodynamics and stationary-wave dynamics. The opposite responses are isolated in model simulations with fixed sea surface temperature. The importance of land-sea thermal contrasts in the circulation response is confirmed using idealized aquaplanet simulations. Our results highlight the importance of distinguishing weak circulation responses to global warming that arise due to compensating effects that are robust and physically understood from those that are associated with genuine uncertainty. Compensation places fundamental limits on the detection and attribution of circulation responses to global warming.