(CN) – Massive ice sheets in Greenland, the Antarctic and other locations lost more than 9 trillion tons of ice in the past five decades – adding over an inch of water to global sea levels.
An international team of researchers led by the University of Zurich traversed the frigid terrains of over 19,000 glaciers and studied satellite images of ice fields to analyze the effects of ice melts between 1961 and 2016.
“By combining these two measurement methods and having the new comprehensive dataset, we can estimate how much ice has been lost each year in all mountain regions since the 1960s,” lead researcher Michael Zemp said in a statement. “The glaciological measurements made in the field provide the annual fluctuations, while the satellite data allows us to determine overall ice loss over several years or decades.”
Satellites measured the surface of the Earth, providing researchers with data on changes in ice thickness which was then used to reconstruct ice melts at different points of glaciers over time.
The study, published Monday in the journal Nature, found that ice melt raised global sea levels by 27 millimeters – just over an inch – in the examined time period, accounting for nearly 30% of rising sea levels.
“Globally, we lose about three times the ice volume stored in the entirety of the European Alps – every single year,” Zemp said, adding that melting glaciers lose 335 billion tons of ice each year.
The glaciers that lost the highest volumes of ice were in Alaska, followed by glaciers in the massive, melting ice fields of the Patagonia region in South America.
Glaciers in New Zealand, the European Alps and the Caucasus also suffered significant ice loss during the examined period but contributed very little to rising sea levels worldwide due to their relatively small size, the study found.
Global sea-levels rose at an accelerated rate from about 2.2 millimeters a year to 3.3 millimeters between 1993 and 2014, with melting on Greenland largely to blame.