Earth has lost over 12 trillion tons of ice from Greenland and Antarctica since 1979, study finds

About 12.5 trillion tons (11.3 trillion metric tons) of ice from glaciers in Greenland and Antarctica have melted since 1979, which is enough frozen water to stack ice 5 feet (1.5 meters) deep across the continental United States, according to a major scientific report. A warming Earth is accelerating the melting of the planet's two major ice sheets, with five-sixths of the melt not coming from hotter air, but from warmer waters eroding the ice sheets from below and the sides, with glaciers flowing into the oceans, according to a study published in Wednesday's journal Scientific Data. The study's authors indicated that this trend poses risks for future sea level rise. "The ice sheets are melting away fast," said study co-author Eric Rignot, an ice scientist at the University of California, Irvine. "We are melting the polar regions, sea level is rising worldwide and will exacerbate the vulnerability of coastal regions." The report noted that all the melted ice has turned into nearly 3 quadrillion gallons of water (11.3 quadrillion liters), which has pushed global sea levels up about an inch (3.1 centimeters) since 1979, in addition to other climate factors affecting ocean heights. Lead study author Ines Otosaka, an ice scientist at Northumbria University in England, stated that for every third of an inch (or centimeter) of sea level rise, another 2 to 3 million people experience flooding at least once a year. The Jakobshavn glacier in Greenland is now retreating up to 164 feet (50 meters) a day, Otosaka reported. The international collaboration of polar scientists, led by the European Space Agency, previously only examined ice sheet melt since the 1990s based on European satellite data. By incorporating NASA satellites, the scientists were able to track ice sheet volumes in Antarctica back to 1979 and in Greenland back to 1972. Otosaka noted, "There is a clear trend that the ice sheets are losing more mass and it has been increasing from decade to decade, especially if you look at the ice being discharged to the ocean." The study indicated that in the 1970s, 1980s, and into the 1990s, the ice sheets were relatively stable, but significant melting began in the 2010s. Otosaka expressed concern that changes are tracking decades behind global warming, suggesting that they will continue for decades even if efforts to stop heating the planet are successful. The authors observed a temporary pause in the accelerating numbers from 2020 to 2023, attributing it to short-term weather variations rather than long-term trends. Otosaka mentioned that while the study concluded with 2023 data, she has observed that the accelerating trend has resumed. The authors explained that the stability in Antarctica was partly due to record snowfall in East Antarctica, which compensated for rapid melting in the less stable West Antarctic Ice Sheet. Rignot described the three-year hiatus as "just a bump in the record," emphasizing that the long-term rise is linked to climate change. The study highlighted significant changes in dynamic processes, which are more abrupt and active compared to steady melting from the air, and these processes could trigger runaway "tipping points," according to Otosaka. David Holland, an ice scientist at New York University, expressed concern about the predominance of dynamical ice loss, which aligns with expectations of ice sheet instability collapse scenarios. The international team utilized 45 independent surveys and 27 different satellites, with Holland stating, "The use of relatively independent methods gives me greater confidence in the result. The upward trend is real." Ted Scambos, an ice scientist at the University of Colorado who was not involved in the study, remarked that the challenges posed by Antarctic mass loss are significant for future human management of the planet, indicating a clear and present danger that may manifest in many decades. The article includes a photo of the Collins Glacier in Fildes Bay, Antarctica, taken on February 2, 2019.