A West Antarctic ice sheet that is roughly the size of Texas is losing the amount of ice equivalent to Mount Everest every two years, representing a melt rate that has tripled over the last decade, according to new research to be published in the journal Geophysical Research Letters on Friday.
To get their results, scientists from the University of California-Irvine and NASA analyzed more than 20 years worth of data representing what’s called the “mass balance” of glaciers in the Amundsen Sea Embayment, an ice sheet that flows into the Amundsen sea. The “mass balance” measurement takes into account the fact that glaciers gain and lose ice over time, and measures the average.
What they found was staggering: The glaciers in the Amundsen Sea Embayment are averaging a loss of 83 gigatons, or 91.5 billion U.S. tons, of ice per year — a rate that has accelerated by an average of 6.7 billion tons every year since 1992.
“The mass loss of these glaciers is increasing at an amazing rate,” said Isabella Velicogna, a co-author of a published paper explaining the findings, in a statement, noting uncertainty as to how the melt would eventually affect sea level rise. Glaciers generally represent a type of land ice, meaning they impact sea level rise when they melt. But they also tend to gain back ice during the colder season, meaning it’s unclear how quickly the ice loss will be morph into sea level rise. If all the glaciers along West Antarctica’s Amundsen Sea melted, would raise sea levels by approximately four feet.
“It’s critical that we maintain this network to continue monitoring the changes,” Velicogna said, “because the changes are proceeding very fast.”
The study represents the latest published research to show the vulnerability of the entire West Antarctic Ice Sheet, an area that NASA recently deemed “unstable” — facing a melt that “appears unstoppable” in the face of global warming. Of that entire ice sheet, the Amundsen Sea Embayment is considered the most vulnerable, melting faster than any other area of the Antarctic.
CREDIT: NATIONAL SNOW AND ICE DATA CENTER
Like most published research of ice melt in the Antarctic and beyond, the findings also run contrary to a common climate denier talking point — that ice levels have actually risen over time, both in the Arctic and in Antarctica. That talking point, however, misrepresents the natural variability in ice loss and ice gain, focusing on short-term increases in sea ice mass that have nothing to do with the long-term decline.
For Antarctica, it’s a bit more complicated. While the area is actually gaining sea ice, it’s losing land ice at an accelerating rate. Sea ice is like an ice cube in a glass — if it melts, it doesn’t effect sea level rise. If land ice melts, however, sea levels are impacted.
In the Antarctic, its West and East ice sheets — both land ice masses — are the most important things to look at. In the Arctic, however, sea ice is just as important to look at, because when it melts, more sunlight is absorbed by the oceans. In Antarctica, sea ice melt is less of a problem for ocean warmth.
The Amundsen Sea Embayment is not the only icy land mass that scientists are worried about. In the Andes Mountains, tropical glaciers are melting, threatening freshwater supplies in the Andes. And while not melting at that rate yet, some scientists have predicted that the Greenland Ice Sheet — which covers about 80 percent of the massive country — is approaching a “tipping point” that could also have “huge implications” for global sea levels and ocean carbon dioxide absorption.