According to a Rutgers University-New Brunswick study, warming waters in the western tropical Pacific Ocean have significantly increased thunderstorms and rainfall, which may affect the stability of the West Antarctic Ice Sheet and global sea-level rise. The study was published in the journal Geophysical Research Letters.
West Antarctic, a massive ice sheet that sits on land, has been melting and contributing to global sea-level rise since the mid-1990s. This century, that melting has accelerated. Elements that play a crucial role in it are wind and weather in governing the fusion. Winds push warm ocean water toward the ice sheet and melt it from below, at the same time as winds bring warm air over the ice sheet surface and melt it from above.
The new research discovered that the South Pacific Convergence Zone, a region of the western tropical Pacific, is the primary driver of weather variability across West Antarctica.
A former post-doc who was the leader of the study at Rutgers-New Brunswick and is now at Victoria University of Wellington in New Zealand, Kyle Clem, said that with so much at stake, in coastal communities around the globe, including in New Jersey, it is quite essential understanding the drivers of weather variability in West Antarctica. By knowing how all regions of the tropics influence West Antarctica, both independently and collectively, will help them understand past climate variability there and perhaps help them predict the future state if the ice sheet and its potential contribution to global sea-level rise.
The research of the Rutgers team involved how warming ocean temperatures in the western tropical Pacific influence weather pattern around West Antarctica. This century, the Antarctic Peninsula and interior West Antarctica have been cooling while the Ross Ice Shelf has been warming, a reversal of what happened in the second half of the 20th century. From the 1950s to the 1990s, the Antarctic Peninsula and interior West Antarctica were the most rapidly warming regions on the planet, and the Ross Ice Shelf was cooling.
At the beginning of the century, the temperature trends flipped. Coinciding with the flip in West Antarctic temperature trends, ocean temperatures in the western tropical Pacific began warming rapidly. The team used a climate model and discovered that warming ocean temperatures in the western tropical Pacific have resulted in a significant increase in thunderstorm activity, rainfall, and convection in the South Pacific Convergence Zone. Convection in the atmosphere is when heat and moisture move up or down.
The rise in rainfall in the zone results in cold southerly winds over the Antarctic Peninsula and warm northerly winds over the Ross Ice Shelf, consistent with the recent cooling and warming in those respective regions. So, the West Antarctic climate, although isolated from much of the planet, is profoundly influenced by the tropics. The results of the study may help scientists interpret the past West Antarctic climate as recorded in ice cores.