A massive new study by 16 authors has calculated just how much ice the Greenland ice sheet has lost since the year 1900. And the number, says the paper just out in the journal Nature, is astounding: 9,103 gigatons (a gigaton is a billion metric tons).
That’s more than 9 trillion tons in total. And moreover, the rate of loss has been increasing, the research finds, with a doubling of annual loss in the period 2003 to 2010 compared with what it was throughout the 20th century.
The study was led by Kristian K. Kjeldsen of the Natural History Museum of Denmark. The complex work involved inferring the loss of mass of the total ice sheet over a very large stretch of time using a merger of multiple information sources: the distinct marks left by retreating glaciers on the landscape, extensive aerial photography from 1978 through 1987, and — beginning in 1983 — satellite and aircraft observations. The paper suggests glacier retreat was more or less kicked off around 1900, at the end of a cooling period — and then accelerated as major human-caused global warming kicked in.
