The role of the Arctic and Antarctic and their impact on global climate change:Further findings since the release of IPCC AR4,2007

Changes in the climate of the Arctic and of the Antarctic have been of great concern to the international scientific and social communities since the release in 2007 of the Intergovernmental Panel on Climate Change Fourth Assessment Report （IPCC AR4）. Since then, many new findings have been reported from observations and research carried out in the Arctic and Antarctic during the fourth International Polar Year （IPY）. There is evidence that global warming is inducing rapid changes in the Arctic and Antarctic, in both a quantitative and qualitative sense, and that these regional changes could be used as indicators of global climate change. Declining Arctic sea ice could affect winter snowfall across much of the Northern Hemisphere by bringing harsher winters. Projections suggest that summertime Arctic sea ice will disappear by 2037. By the 2070s, the Antarctic ozone hole will recover to the level of the early 1980s, following the ban on the production of Freon earlier this century. With the loss of the shielding effect of the ozone hole, Antarctic surface temperatures will increase, ice sheets in East Antarctica will begin to melt, and the Antarctic sea ice will retreat. Therefore, sea level rise will become an increasingly serious issue this century. As sea surface temperature rises, the Southern Ocean will become less effective as a sink for atmospheric CO2 and the increase of surface CO2 will be faster than that in the atmosphere. Increased surface CO2 would lead to ocean acidification and affect ecological systems and food chains.

The relationship between polar sea ice and the precipitation and temperature over China revealed by using SVD method

The relationship between polar sea ice anomalies and the precipitation and temperature anomalies over China is investigated by performing singular value decomposition (SVD) analyses. The first three coupling modes have been studied. Analyses show that there exist key areas of polar sea ice which are highly related with the precipitation and temperature anomalies over China. Different spatial anomaly patterns of these areas of polar sea ice are followed by different spatial anomaly patterns of the precipitation and temperature over China.

Improved sea-ice radiative processes in a global coupled climate model

The NASA Goddard Institute for Space Studies (GISS) coupled global climatemodel was used to investigate the sensitivity of sea ice to improved representations of sea-iceradiative processes: (1) a more sophisticated surface albedo scheme and (2) the penetration of solarradiation in sea ice. The results show that the large-scale sea-ice conditions are very sensitiveto the aforementioned parameteriza-tions. Although the more sophisticated surface albedo schemeproduces a more realistic seasonal cycle of the surface albedo as compared with the baselinesimulation, the resulting higher albedo relative to the baseline simulation generates much more andthicker ice in the arctic. The penetration of solar radiation in sea-ice itself tends to reduce theice cover and thickness in the entire arctic and the western antarctic, and increase the ice coverand thickness in the eastern antarctic. The combination of (1) and (2) significantly improves thesimulations of the average ice thickness and its spatial distribution in the arctic. The atmosphericresponses associated with sea-ice changes were also discussed. While improvements are seen,particularly of the ice thickness distribution, there are still some unrealistic aspects that willrequire further improvements to the sea-ice component.