Summary
Australia and New Zealand have interests in, and some responsibilities for, a vast area of the Southern Ocean and the Antarctic continent to our south. These regions are integral components of the Earth system, directly coupled to the climate system, global sea level, biogeochemical cycles, ecosystems, and human activities. Changes that are occurring to our global climate are amplified at high latitude, and feedback to drive changes elsewhere on the Earth. This presentation will focus on the science behind climate change. It will review recent large-scale changes to the physical environment of Antarctica and the Southern Ocean, their impacts on marine ecosystems, and their potential future effects on lower latitudes. The issue of climate change, an issue which may lead to the need to introduce new environmental protection legislation, has come to prominent attention of the wider community through the changes detected in such areas as Antarctica. Recent studies, many of which were conducted during the International Polar Year 2007-2008 (IPY), have revealed large scale changes to our south. New satellite assessments reveal that the Antarctic ice sheet is losing ice and thus contributing to sea level rise. This loss is largely due to increased ice outflow, and the potential for further rapid increase in ice discharge remains the largest unknown in IPCC projections of the rate of sea level rise. Data from robotic ocean profiling floats, instrumented marine mammals and IPY research vessels confirm that the Southern Ocean, and particularly the southern flank of the Antarctic Circumpolar Current, has warmed more rapidly than the global ocean average. In addition, the dense bottom water formed near Antarctica has freshened in some locations and warmed in others, consistent with increased melt from the Antarctic ice shelves and ice sheet. A complicated picture has emerged of interconnections between ozone concentrations above Antarctica, the size and intensity of the polar vortex, and wind at the surface over the Southern Ocean.