Melting ice in Greenland linked to Arctic warming
WSWS, Jun 24 2016
Research in Nature Communications has shown that the warm waters of the Arctic over the past year, a result of lower levels of sea ice caused by increasing global temperatures, are likely linked to an increased amount of melting ice in Greenland in 2015. One of the doomsday scenarios for global warming is for the Greenland ice sheet, second in size only to Antarctica, to melt completely. In doing so, it would raise global sea levels by about seven meters, permanently flooding cities and coastal areas where about one-third of the world’s population lives. In fact, most of the rise in sea level since 2000 has been a result of increased melting from Greenland. Accordingly, understanding and forecasting the level of ice melting off of Greenland is a high priority among climate scientists. Arctic temperatures have peculiarly large effects on Greenland’s ice because of what is known as Arctic amplification. This refers to the fact that temperatures in the Arctic are increasing faster than other parts of the Northern hemisphere as the sea ice in that region melts. As more sea ice melts, less sunlight is reflected back to space and more heat is absorbed by the exposed water. This has created a positive feedback loop that is strong enough to influence temperatures, particularly in Northern Greenland, causing more melting than normal. This was exacerbated by higher surface temperatures and lower snowfall amounts over that region last year. Another effect, though not as well understood, is the impact of warmer Arctic temperatures on the jet stream. Climate models have shown that as the temperature difference between the Arctic and temperate zone decreases, warmer air from southern latitudes will begin penetrating further north. This is a change from the standard jet stream, which normally acts to separate the cold polar air from warm air in the south. Though more data needs to be collected on this process, what has been obtained over the past decade suggests that the jet stream might start acting as a warming agent instead of a cooling agent over Greenland. The melt of 2015 will likely continue into this year. Already, the melting measured in April is comparable to what occurred in Apr 2012, which was the precursor to record-setting melting that occurred later that summer.