Measuring melting ice is a fairly precise business in 2019 - thanks to satellites, weather stations and sophisticated climate models.
By the 1990s and 2000s, scientists were able to make pretty good estimates, although work from previous decades was unreliable due to less advanced technology. Now, researchers have recalculated the amount of ice lost in Greenland since 1972, the year the first Landsat satellites entered orbit to regularly photograph the Danish territory.
Glaciologists use three methods to measure ice melting.
Firstly, satellites measure altitude with a laser, and if a glacier melts, the satellite picks up its reduced height. A second technique involves measuring variations in gravity, as ice loss can be detected through a decrease in gravitational pull. This method has been available since 2002 using NASA satellites. Thirdly, scientists have developed so-called mass balance models, which compare mass accumulated (rain and snow) with mass lost (ice river discharges) to calculate what is left. The research team used these models to "go back in time" and reconstruct Greenland's ice levels in the 1970s and 1980s.
The results: During the 1970s, Greenland accumulated 47 gigatonnes of ice per year, on average. Then, it lost an equivalent volume in the 1980s. The melting continued at that rate in the 1990s, before a sharp acceleration in the 2000s (187 Gt/year) and even more since 2010 (286 Gt/year).
Ice is melting six times faster than in the 1980s, researchers estimate
and Greenland's glaciers alone have contributed to a 13.7 millimeter rise in sea levels since 1972, they believe.
As with a similar study carried out by the same team on Antarctica, the new study affords a longer term view of the rapid ice melt being observed in Greenland in recent years.
"This new data better enables us to put recent, dramatic, changes to Greenland's contribution to global sea level rise into a longer-term context - the ice loss we've seen in the last eight years is as much as was lost in the preceding four decades," said Amber Leeson, a lecturer in Environmental Data Science at Lancaster University.
Please click to read our informative text prepared pursuant to the Law on the Protection of Personal Data No. 6698 and to get information about the cookies used on our website in accordance with the relevant legislation.
6698 sayılı Kişisel Verilerin Korunması Kanunu uyarınca hazırlanmış aydınlatma metnimizi okumak ve sitemizde ilgili mevzuata uygun olarak kullanılan çerezlerle ilgili bilgi almak için lütfen tıklayınız.