How could a difference of 0.5°C in global warming modify the mean and extreme climate conditions around Antarctica?

Abstract

This paper quantifies the potential benefit of limiting the global warming to 1.5 C above the preindustrial level on the high-latitude climate of the Southern Hemisphere compared to 2.0 C and above. A set of Coupled Model Intercomparison Project Phase 5 global climate model experiments is used in order to determine the mean projected changes in surface air temperature, sea level pressure, surface winds and sea ice distribution over and around Antarctica. Alongside, changes in selected variables related to extremes (such as the annual number of extremely cold mornings and extremely cold days) are also quantified as a function of the Representative Concentration Pathway (RCP) considered reaching the given warming threshold. Physical mechanisms for the projected variations in sea ice are proposed, including surface air temperature, changes in low-level air temperature advection and meridional winds. Results show that there would be significant differences in the atmospheric and sea ice variable changes depending on the warming threshold and RCP considered, and that indeed keeping the global warming under 1.5 C could have a noticeable impact particularly on the distribution of sea ice over the Southern Ocean.