(Courthouse News Service) Melting Antarctic ice has raised global sea levels by more than a quarter of an inch since 1992, with 40 percent of the increase occurring in the past five years, according to a study published Wednesday in the leading scientific journal Nature.
The findings come from the Ice Sheet Mass Balance Intercomparison Exercise, a major climate assessment involving 84 researchers from 44 international organizations, who combined 24 satellite surveys to produce the analysis.
The Nature study shows that before 2012, Antarctica was losing 76 billion tons of ice each year: a nearly 0.08-inch annual contribution to sea level rise.
Since then there has been a drastic, threefold increase, with the continent losing 219 billion tons of ice a year between 2012 and 2017.
“Gravity measurements from the GRACE (Gravity Recovery and Climate Experiment) mission help us track the loss of ice mass in the polar regions and impacts on sea level at points around the planet,” said co-author Isabella Velicogna, a professor of Earth system science at the University of California, Irvine (UCI).
“The data from GRACE’s twin satellites show us not only that a problem exists, but that it is growing in severity with each passing year.”
GRACE is a joint mission between NASA and the German Aerospace Center.
Antarctica holds enough frozen water to raise global sea levels by more than 190 feet, so understanding how much ice it is losing is critical to understanding the impact of climate change.
The threefold increase in ice loss from the continent comes from quicker melting in West Antarctica and the Antarctic Peninsula, and reduced growth of the ice sheet in East Antarctica.
West Antarctica underwent the most dramatic change, from losing 53 billion tons of ice annually in the 1990s to losing 159 billion tons each year since 2012. Most of this stems from the massive Pine Island and Thwaites glaciers, which are melting rapidly due to warm ocean waters.
Ice shelf collapse in the Antarctic Peninsula has sparked a 25 billion ton rise in ice loss since the early 2000s. Researchers believe East Antarctica’s ice sheet has remained fairly stable over the past 25 years.
“With the number of scientific studies focusing on this region, the technological tools we have at our disposal and datasets spanning several decades, we have an unequivocal picture of what’s happening in Antarctica,” said co-author Eric Rignot, chairman of Earth system science at UCI. “We are confident in our understanding of ice mass change in Antarctica and its impact on sea levels.
“We view these results as another ringing alarm for action to slow the warming of our planet.”