About 12.5 trillion tonnes of ice from Greenland’s and Antarctica’s glaciers have melted since 1979, equating to frozen water sufficient to form a layer of ice 1.5 meters deep across the continental United States, according to a major scientific report.
Global warming is accelerating the melting of the planet’s two largest polar ice caps. According to a study published in the journal Scientific Data, five-sixths of this melt does not come from the hottest air, but rather from warmer waters that erode the polar caps from below and along the sides, with the glaciers flowing into the oceans. This is bad news for future sea level rise, the study authors stated.
“The polar caps are melting rapidly,” said the study’s co-author, Eric Rignot, an ice scientist at the University of California, Irvine. “We are melting the polar regions, sea levels are rising worldwide, and this will worsen the vulnerability of coastal regions.”
The numbers behind the melt are at once incredibly large and deceptively small.
All of this melted ice turned into nearly 11.3 quadrillion liters, which raised the global sea level by about one inch (3.1 centimeters) since 1979, in addition to other climatic factors that have also increased the height of the oceans, according to the report. One inch may not seem like much, but for every one-third of an inch rise in sea level, another 2 to 3 million people experience flooding at least once a year, said the study’s lead author, Ines Otosaka, ice scientist at Northumbria University in England.
The Jakobshavn Glacier in Greenland is retreating up to 50 meters per day, Otosaka said.
The international collaboration of polar scientists, led by the European Space Agency, had analyzed the melting of the polar caps only since the 1990s, based on data from European satellites. But by incorporating NASA satellites, the scientists were able to map the volumes of the polar caps in Antarctica since 1979 and in Greenland since 1972.
The melting is accelerating
“There is a clear tendency that the polar caps are losing more mass, and this has been increasing decade after decade, especially when we consider the ice that is released into the ocean,” Otosaka said. “And that makes it very clear that there is a link to climate change.”
“This showed that, in the 1970s, 1980s, and 1990s, the ice sheets were relatively stable, but then the melting actually intensified during the 2010s,” Otosaka said. “This is worrying, because it shows that changes are occurring decades after global warming, which means we can expect them to continue for decades more—even if we manage to prevent warming of the planet,” said the study’s co-author, Andrew Shepherd, also from Northumbria University.
The rising numbers appeared to plateau between 2020 and 2023, but the study authors stated that this reflected more short-term climate variations than long-term trends. Otosaka said the study stopped at 2023 data, but she analyzed later measurements and found that the acceleration trend had resumed.
The authors stated that much of the stability in Antarctica was due to East Antarctica recording record snowfalls, which offset the rapid melt in the less stable West Antarctic ice. The three-year pause was “just a small blip in the record,” said Rignot. “The big worry is the climate, and the threat is crystal clear.”
Concerns about a collapse scenario
The greatest changes observed by scientists are in what they call dynamic processes, which are more abrupt and active than the slow and steady melting from the air, and this is something prone to triggering uncontrolled “tipping points,” Otosaka said.
David Holland, a glaciologist at New York University, said that is what concerns him, “because most of the ice loss is dynamic, and that is exactly what would be expected in a scenario of ice-sheet instability collapse.”
The international team used 45 independent surveys and 27 different satellites. “Using relatively independent methods gives me greater confidence in the result,” said Holland, who did not participate in the study. “The upward trend is real.”
“The unpredictable factors of mass loss in Antarctica continue to pose a challenge for human management of the planet – a clear and present danger, but one that will only manifest itself in many decades,” said Ted Scambos, a glaciologist at the University of Colorado, who did not participate in the study. “As a society, we are intelligent enough to foresee the future, but not prudent enough to act on that knowledge.”
*Content translated with the aid of Artificial Intelligence, reviewed and edited by the Broadcast newsroom (Grupo Estado’s real-time news system).
