Why does the Antarctic Peninsula Warm in Climate Simulations?

The Antarctic Peninsula has warmed significantly since the 1950s. This pronounced and isolated warming trend is collectively simulated by 29 twentiethcentury climate hindcasts participating in the version 3 Coupled Model Intercomparison Project. To understand the factors driving warming trends in the hindcasts, we examine trends in Peninsula region’s atmospheric heat budget in every simulation. Atmospheric latent heat release increases in nearly all hindcasts, and is generally anthropogenic in origin. These increases are driven primarily by well-understood features of the anthropogenic intensification of global hydrological cycle. As sea surface temperature increases, moisture contained in atmospheric flows increases. When such flows are forced to ascend the Peninsula’s topography, enhanced local latent heat release results. The latent heat increases are the most important cause of simulated anthropogenic warming in the Antarctic Peninsula because they are typically much larger than the warming effects associated with other types of heat fluxes and because their magnitudes are tightly correlated with the amount of warming in the Peninsula. Based on this study, we judge it likely that the warming of the Antarctic peninsula will continue over the course of the 21st century.