Antarctica's ice sheets contain enough water to raise sea levels by 190 feet (58 meters), but the overall contribution to sea level rise has been small: A mere 7.6 millimeters between 1992 and 2017.
That may not seem like much — it's half the size of a 325 milligram dose of aspirin, after all — but the bad news is that the rate of ice loss is increasing, and quickly.
That's the conclusion of a study conducted by 84 scientists from 44 international organizations and published in Nature. Prior to 2012, Antarctic ice loss resulted in a 0.2 mm sea level increase each year, with no notable increase from that over time. Since 2012, however, the rate has tripled to 0.6 mm a year, with 3 mm of that 7.6 mm figure mentioned above coming in the last five years alone.
"According to our analysis, there has been a steep increase in ice losses from Antarctica during the past decade, and the continent is causing sea levels to rise faster today than at any time in the past 25 years," the study's co-lead author and University of Leeds professor Andrew Shepherd said in a statement. "This has to be a concern for the governments we trust to protect our coastal cities and communities."
Satellites observe gains and losses
Shepherd and the other scientists relied on data compiled from 24 satellite surveys to determine how much ice sheets in Antarctica were thickening or thinning over time, how fast the glaciers were moving and Antarctica's gravity measurements. That last measurement can be related to the overall mass of the ice sheets, according to NPR.
The loss comes from across the continent as a whole, according to the researchers, with different regions behaving differently. The West Antarctic ice sheet, for example has seen the biggest changes, with ice losses rising from 53 billion tonnes per year in the 1990s to 159 billion tonnes a year since 2012. The Pine Island and Thwaites glaciers contributed the most to these losses due to ocean melting.
The East Antarctic ice sheet has kept a "close to a state of balance over 25 years;" it gains an average of just 5 billion tonnes of ice a year.
Climate change, which has caused ocean temperatures to rise, is considered the primary driver behind the increase in ice loss.