The threat of the Greenland ice sheet slipping ever faster into the sea because of warmer summers has been ruled out by a scientific study.

Until now, it was thought that increased melting could lubricate the ice sheet, causing it to sink ever faster into the sea. The issue was a key unknown in the landmark 2007 report from the Intergovernmental Panel on Climate Change, which pinned the blame for climate change firmly on greenhouse gas emissions from human activities.

However, the impact of rising sea temperatures on melting ice sheets is still uncertain, meaning it remains difficult to put an upper limit on potential sea level rises. Understanding the risk is crucial because about 70% of the world's population live in coastal regions, which host many of the world's biggest cities, such as London, New York and Bangkok.

"The Greenland ice sheet is safer than we thought," said Professor Andrew Shepherd of the University of Leeds, who led the research published tomorrow in Nature. [ GUARDIAN UK ]