Gelo marinho antártico: tendências de 1978 a 2006

Abstract

Sea ice plays an important role on Earth’s climate. Besides its high albedo, sea ice isolates ocean from atmosphere reducing the heat flux between them and is in part responsible for deep water formation through brine expulsion. However, these processes can be affected by the recent global temperature increase. The objectives of this work are to calculate the long term trends of sea ice concentration and extension and try to make the relation, even preliminarily, between these trends and climate change. For this, analyses such as linear regression and correlation were made with SMMR and SSMI data for the 1978-2006 period. The results show that almost all Antarctica’s regions have a positive trend except the Bellingshausen/Amundsen Seas. The reasons for this are not well established, but processes like increase of air and water temperature, El Niño events, and positive trends for SAM index are pointed as being critical factors influencing this area. For the whole Southern Ocean, the trend was significant and positive, in opposition to the Arctic’s sea ice extension trend. To find the possible causes for these trends, we need to take into account the several processes that happen in these areas and their behavior over time and not consider just one factor to be responsible. We have to remember that the time series is relatively short and that these trends can just be the ascending part of a major cycle.