Contrasting Observed Atmospheric Responses to Tropical Sea Surface Temperature Warming Patterns

Equilibrium climate sensitivity (ECS) is a theoretical concept which describes the change in global mean surface temperature that results from sustained doubling of atmospheric CO2. Current ECS estimates range ∼1.8 to 5.6 K, reflecting uncertainties feedbacks. The lower (1,000–700 hPa) and upper (500–200 troposphere changes spatial patterns tropical sea (SST) have been proposed by recent model studies as key feedbacks controlling sensitivity. We examine empirical evidence for these mechanisms using 14 years satellite data. response humidity profiles, clouds, top-of-the-atmosphere radiation relative warming ocean regions when there either strong convection or subsidence. find warmer SSTs subsidence are coincident with decrease tropospheric stability (−0.9 ± 0.4 KK−1) low cloud cover (∼−6% K−1). This leads associated weakening shortwave cooling effect clouds (4.2 1.9 Wm−2K−1), broadly consistent calculations. In contrast, an increase (3.2 1.5% this scenario, dominant enhancement longwave radiative (3.8 3.0 Wm−2K−1) high (∼7% K−1), though net (longwave shortwave) not statistically significant (p < 0.003). Our observational supports existence linking contrasting responses SST, linked