How Much Ice Is Greenland Losing? Researchers Found an Answer.
How Much Ice Is Greenland Losing? Researchers Found an Answer.
Excerpt from this New York Times story:
Greenland’s expansive ice sheet is known to be shrinking, especially since the 1990s, because of warming from climate change. It’s a fate shared by the Antarctic Ice Sheet as well as glaciers around the world. Now, a new study reveals that about 20 percent more of the Greenland ice sheet has disappeared than previous estimates show.
The missing ice has been breaking and melting from the ends of glaciers around Greenland’s perimeter. The new research, published Wednesday in the journal Nature, provides a detailed accounting of a process that scientists knew was happening but had struggled to measure comprehensively.
“Almost every glacier in Greenland is retreating. And that story is true no matter where you look,” said Chad Greene, a glaciologist at the NASA Jet Propulsion Laboratory and the lead author of the study. “This retreat is happening everywhere and all at once.”
Because the ends of these glaciers generally sit below sea level, within deep fjords, their retreat isn’t directly adding a significant amount to sea level rise. But melting ice still adds an influx of freshwater that has implications for global climate models and projections, and for the system of ocean currents that regulates temperatures on both sides of the Atlantic Ocean.
Dr. Greene’s team combined more than 200,000 observations of glacier end points, covering almost all of Greenland, based on satellite images taken from 1985 to 2022. The researchers used observations from existing public data sets and combined them to create a comprehensive bird’s-eye view of the contracting edges of Greenland’s ice sheet over the past 40 years.
Combining several of these estimates, scientists arrived at a consensus that Greenland has lost a total of nearly five trillion metric tons of ice since 1992.
The erosion of these glaciers’ end points has an indirect effect on sea levels. Dr. Greene compared glacial terminus retreat to unplugging a drain, allowing the whole glacier to flow faster and thin out, accelerating melt from the parts above sea level as well.
So, while this study does not measure a direct addition to sea level rise, he said, “we’re probably measuring a cause of sea level rise.”