Until now, it had been thought that melting ice could form a slippy layer at the bottonm of the Greenland ice sheet causing it to slide rapidly into the sea. Now, a study by Professor Andrew Shepherd of the University of Leeds, has shown that this is not happening.
Professor Shepherd’s team used satellite imagery to track the progress of the west Greenland ice sheet each summer, over five years. They found that, above a certain threshold, the slipping begins to slow. On-the-ground studies and work done on alpine glaciers suggests that higher volumes of meltwater actually forms channels under the ice. These allow the water to drain more efficiently and reduce the formation of a lubricating film.
The Greenland ice sheet is up to 1,000m thick. If the entire ice sheet melted, sea levels worldwide would rise by an average of seven metres. However, Professor Shepherd says that "The Greenland ice sheet is safer than we thought." In fact, if only way in which the ice melts is by being warmed from the air, it would take about 3,000 years to melt completely.
Professor Shepherd is now studying the question of whether warmer oceans could melt the edges of ice caps, causing the ice behind them to fall into the sea. This is a particular concern in West Antarctica which contains enough ice to raise sea levels by an average of six metres worldwide.
Asked if he thought his work suggested the wider risks of global warming could be discounted, he said: "Not at all."
