Sea Ice and Climate Change: Insights from Models and Satellite Data

Claire L. Parkinson

Oceans and Ice Branch
NASA Goddard Space Flight Center

Sea ice limits exchanges between the oceans and the atmosphere, reflects incoming solar radiation back to space, and has an array of additional impacts on polar climates and ecosystems. Some of these impacts produce positive feedbacks within the climate system, and, indeed, early conceptual models and global climate model (GCM) simulations both indicated that the positive feedbacks brought about by snow and ice are likely to produce an enhanced sensitivity to climate change in the polar regions versus the rest of the globe. However, as the models have advanced, these indications have proven to be more robust for the north polar region than the south. The satellite record over the past three decades shows a sharp contrast between the changes in the two polar ice covers, although with a high degree of spatial and interannual variability in both. The Arctic ice cover, overall, has decreased, garnering considerable scientific and media attention because of possible connections with global warming. Along with the overall decreases, however, the data additionally reveal intriguing spatial and temporal patterns in the Arctic ice cover changes that suggest possible ties to oscillatory patterns in the atmosphere. In the Antarctic, the sea ice cover decreased markedly in the 1970s but, overall, has increased since then. This talk will review some of the model simulations and the observational record of the Arctic and Antarctic sea ice covers as revealed from satellite passive-microwave data.