Around 12.5 trillion tonnes of glacier ice in Greenland and Antarctica have melted since 1979, according to a study published today in the journal ‘Scientific Data’, which warns of an increasing vulnerability of coastal regions.
The warming of the Earth is accelerating the melting of the planet’s two main ice sheets, but five-sixths of this melting does not result from warmer air, but from warmer waters that affect the ice sheets as glaciers flow into the oceans.
“The ice sheets are melting rapidly,” said the study’s co-author, Eric Rignot, an ice expert at the University of California, arguing that the melting ice in polar regions and the global sea level rise will worsen the vulnerability of coastal regions.
All that melted ice has turned into nearly three quadrillion water jugs (11.3 quadrillion liters), which has raised the global sea level by about 3.1 centimetres since 1979, in addition to other climatic factors that also raise ocean levels, according to the report.
“These 3.1 centimetres may not seem like much, but for every one centimetre of sea level rise, between two and three million more people suffer floods at least once a year,” said the study’s lead author, Ines Otosaka, an ice specialist at Northumbria University, in the United Kingdom.
Ines Otosaka noted that the Jakobshavn Glacier in Greenland is currently retreating by up to 50 metres per day.
Previously, an international collaboration of polar scientists, led by the European Space Agency, had already analysed the melting of the ice sheets dating back to the 1990s, based on data from European satellites.
Now, by incorporating NASA satellites, scientists have been able to map the volumes of the ice sheets in Antarctica since 1979 and in Greenland since 1972.
The study showed that in the 1970s, 1980s and up to the mid-1990s, the ice sheets were relatively stable, but during the 2010s the melting began to occur and to intensify drastically, according to Ines Otosaka.
“This is a cause for concern, as it shows that changes occur with a lag of decades relative to global warming, which means we can expect them to continue for another few decades, even if we manage to stop warming the planet,” said the study’s co-author, Andrew Shepherd, also from Northumbria University.
The most significant changes observed by the scientists arose from “dynamic processes,” phenomena more abrupt and active than the slow and steady melting caused by the air.
David Holland, a glaciologist at New York University, said that this aspect is what concerns him, “because most of the ice loss is dynamic in nature, exactly what would be expected in a scenario of collapse due to instability of the ice sheet.”
The international team used 45 independent surveys and 27 different satellites to carry out the study.
