Antarctic Peninsula Climate Change during the Instrumental Period presented by Professor John Turner

Since the middle of the Twentieth Century the stations on the Antarctic Peninsula have recorded some of the largest increases in surface temperature on Earth, with the warming being most pronounced during the winter (summer) on the western (eastern) side. Temperature variability is influenced by a number of regional and global factors, including the phase of the Southern Annular Mode and the El Niño Southern Oscillation, as well as the large natural/intrinsic climate variability of the region. Temperatures are strongly influenced by the depth and location of Amundsen Sea Low to the west of the Peninsula, with relatively small changes in the wind field altering the sea ice distribution, which can result in large temperature changes. I will particularly focus on the decrease in annual mean temperature that all the stations have experienced since the late 1990s as a result of changes in the atmospheric jets over the South Pacific. These have resulted in stronger north to northeasterly flow towards the Weddell Sea, increasing the sea ice around the northern part of the Peninsula and giving colder conditions at the stations. The overall increase in temperature of the Peninsula since the 1950s is often held up as an example of ‘global warming’, but the pre-industrial control runs of the IPCC/CMIP5 models and the paleoclimate records suggest that the observed warming is within the bounds of natural variability.