The melting of Greenland’s ice sheet is accelerating, threatening an increasing rise in sea levels.
Satellite measurements showed that the speed of ice-sheet melting had risen threefold in the last two years compared with the average for the previous five years, according to a paper published in today’s edition of the peer-review journal Science.
The accelerated melting has increased to 0.6mm per year the contribution of Greenland’s melting ice to rising sea levels. This represents a large proportion of the total sea level rise of 2mm-3mm a year that the world is experiencing.
Jianli Chen, a research scientist at the University of Texas and lead author of the paper, told the Financial Times: “This [research] gives strong evidence telling us that global warming is there.”
He said the results had tallied with other studies that used different measurements to gauge the melting.
With satellite help, scientists measured the variation in gravity over Greenland, and researchers looked at monthly data between April 2002 and November 2005. “It’s significant that we have found this using an independent tactic,” Mr Chen said.
Greenland’s ice sheet is the second biggest in the world, containing about 2.5m cu km of ice, or 10 per cent of the world’s total ice mass. The University of Texas study found that about 240 cu km are melting every year.
Mr Chen said more observations would be needed in future years to confirm whether the melting was continuing at such an accelerated rate.
Separately, a study published in the same edition of Science found that snow-
fall over Antarctica had shown “no statistically significant” increase in the last 50 years.
The finding is important as some scientists had speculated that the melting of some Antarctic ice would be compensated for by increased precipitation in the middle of the area’s ice sheets, which would increase their thickness.
Andrew Monaghan, research associate at the Byrd Polar Research Centre of Ohio State University and lead author of the paper, said that the “global sea level [rise] has not been mitigated by recently increased Antarctic snowfall as expected”.