WEST ANTARCTIC COLLAPSE - HOW LIKELY

Because most of the world's ice occurs in Antarctica, what might be the possible effects of global greenhouse warming on its ice sheets? In contrast to most mountain glaciers and Greenland, a warming trend is likely to cause an increase in snowfall on Antarctica, which would partially or totally balance the sea-level rise resulting from the melting of ice in the Northern Hemisphere. However, the possibility of dynamic instability in ice sheets exists, particularly for marine ice sheets. If this is the case, a marine ice sheet could collapse in one century or in a few centuries and cause sea level to rise rapidly. Studies in West Antarctica show that some of its ice streams move very rapidly, apparently because of significant basal lubrication. The high ice-stream velocities result in local thinning of ice that might expand and bring about the collapse of the ice sheet. Another possibility is that a global greenhouse effect could warm the ocean waters circulating beneath the ice shelves and melt the ice at its base, even without melting the top surface of the ice. Again, this could lead to the catastrophic collapse of the West Antarctic marine ice sheet and possibly parts of the East Antarctic and Greenland ice sheets as well.