Chapter 13 - Recent climate trends

This chapter discusses recent changes in Antarctic climate. Changes in the atmospheric circulation modes that influence Antarctic climate, namely, the Southern Annular Mode (SAM), the Amundsen Sea Low (ASL), and the Pacific South American pattern (PSA) are highlighted. The transition of the SAM to its positive polarity, the deepening of the ASL, and the enhancement of the PSA over recent years have all contributed to changes in key climate parameters that describe the Antarctic climate. These include the surface air temperature, precipitation, sea ice, and the Southern Ocean. Changes in these parameters along with linkages between them and the atmospheric circulation modes are presented and discussed. Despite a sparsity of observations, changes in surface air temperature, sea ice, and the subsurface ocean have become apparent. Changes in precipitation remain inconclusive. Natural variability and anthropogenic forcing combine with the complex relationships between the atmosphere, sea ice, and ocean to present a challenge to our understanding of the factors underlying the observed changes. Additionally, establishing and understanding the current changes in Antarctic climate, as well as making projections of future changes, are hampered by the limitations of current climate models.