AFP - The Greenland icesheet is more sensitive to global warming than thought, for just a relatively small — but very long term — temperature rise would melt it completely, according to a study published on Sunday.
Previous research has suggested it would need warming of at least 3.1 degrees Celsius (5.6 degrees Fahrenheit) above pre-industrial levels, in a range of 1.9-5.1 C (3.4-9.1 F), to totally melt the icesheet.
But new estimates, published in the journal Nature Climate Change, put the threshold at 1.6 C (2.9 F), in a range of 0.8-3.2 C (1.4-5.8 F), although this would have to be sustained for tens of thousands of years.
Greenland is second to Antarctica as the biggest source of locked-up water on land.
If it melted completely, this would drive up sea levels by 7.2 metres (23.6 feet), swamping deltas and low-lying islands.
If global warming were limited to 2 C (3.6 F), a target enshrined in the UN climate-change negotiations, complete melting would happen on a timescale of 50,000 years, according to the study.
Current carbon emissions, though, place warming far beyond this objective. If they were unchecked, a fifth of the icesheet would melt within 500 years and all would be gone within 2,000 years, the study says. More