U.S. scientists using satellite data have established a more accurate figure of the amount of annual sea level rise from melting glaciers and ice caps.
There are more than 160,000 glaciers and ice caps worldwide but annual changes in mass have been directly measured for only 120 of them and, in most cases, only within the last 30 years.
For the first time, researchers used the GRACE (for "Gravity Recovery and Climate Experiment") satellite system, operated by NASA and Germany, to look at loss of ice by all glaciers and ice caps around the world.
Data, collected for the years 2003 through 2010 indicates that, of the total sea level rise of 3.5 millimetres a year, melting ice contributed an average of 1.48 millimetres a year, the remainder being expansion of sea water due to warming.
The loss of ice from Greenland and Antarctica has already been measured using satellite data at 1.06 millimetres a year.
Melting of glaciers and ice caps outside Antarctica and Greenland accounted for about 0.41 millimetres of the annual rise – a smaller contribution to sea-level rise than had been estimated. The melt rate in the Asian mountains, including the Himalayas, was dramatically lower than expected – only 4 billion tons annually compared to estimates of up to 50 billion tonnes – probably becausing global warming to has not yet been sufficient to melt ice at very high altitudes..