Antarctica is melting, and it’s happening at a much faster rate than scientists previously anticipated.
According to a study published in Nature on Wednesday, losses in Antarctica’s ice sheets—which hold 60 to 90 percent of Earth’s fresh water, The New York Times’ Kendra Pierre-Louis notes—have tripled since 2007.
The study presents the most comprehensive analysis of Antarctic ice loss to date, drawing on 24 surveys conducted by 84 scientists from 44 institutions. These researchers estimate that a decade ago, Antarctica lost ice at a rate of 73 billion metric tons per year. Now, that figure is up to 219 billion tons of ice lost per year, a staggering rate scientists say could raise sea levels six inches by 2100.
To put these numbers into perspective, lead author Andrew Shepherd, a University of Leeds professor of earth observation, tells Pierre-Louis that Brooklyn currently floods about once a year. Adding six inches to sea levels would raise that figure to 20 times a year.
Since 1992, Antarctica has lost more than 3.3 trillion tons of ice, triggering about a quarter-inch rise in global sea levels. Shepherd tells NPR’s Merrit Kennedy that Antarctica’s contributions to rising sea levels made a sharp jump around 2010. Previous estimates said melting ice in Antarctica contributed to seven thousandths of an inch (0.2 millimeters) of annual rise, while the latest numbers are closer to two hundredths of an inch (0.6 millimeters) annually.
The researchers’ central concern is West Antarctica, which experienced an annual loss of 159 billion tons of ice between 2012 and 2017, up from 65 billion tons between 2002 and 2007. The Washington Post’s Chris Mooney reports that warm water from underlying oceans have rendered the region’s glaciers unstable.
Pine Island and Thwaites, two of West Antarctica’s largest glaciers, hold the unwelcome distinction of having the world’s highest annual levels of glacier loss. Thwaites is particularly concerning: It currently acts as a barrier preventing the ocean from reaching West Antarctica, but further ice loss could enable warmer waters to melt the ice sheet into an entirely new body of water.
Meanwhile, East Antarctica’s ice sheet has experienced both gains and losses in mass. Although the region accounts for two-thirds of Antarctica, Pierre-Louis writes that its fluctuations are not enough to make up for the losses seen in West Antarctica.
A separate study also released in Nature speculates on the consequences of rapid ice loss and other indicators of climate change. The paper, co-written by nine winners of the Tinker-Muse Prize for Science and Policy in Antarctica, outlines two scenarios as seen by an observer reflecting back from the year 2070.
Both scenarios are speculative, not decisive forecasts. In one version, global warming has continued unchecked, leaving Antarctica and the Southern Ocean with a dramatic loss of ice shelves and an accompanying acceleration in global sea levels. In the second, human actions have curbed greenhouse gas emissions and human pressure on the environment, enabling Antarctica to look much as it did in the early years of the century—ice shelves intact.
In a statement, lead author Steve Rintoul of the Centre for Southern Hemisphere Oceans Research and Antarctic Climate and Ecosystems Cooperative Research Centre in Hobart, Australia, says, "The trajectory that will play out over the next 50 years depends on choices made today. … The future of Antarctica is tied to that of the rest of the planet and human society. Actions can be taken now that will slow the rate of environmental change, increase the resilience of Antarctica, and reduce the risk that we commit to irreversible changes with widespread impact."