Don’t Believe the Hype About Antarctica’s Melting Glaciers

Two studies carefully explore the factors at play, but the headlines are only meant to raise alarm

By Steven Koonin. Excerpts: 

"Each year, some 2,200 gigatons (or 0.01%) of the ice is discharged in the form of melt and icebergs, while snowfall adds almost the same amount. The difference between the discharge and addition each year is the ice sheet’s annual loss. That figure has been increasing in recent decades, from 40 gigatons a year in the 1980s to 250 gigatons a year in the 2010s.

But the increase is a small change in a complex and highly variable process. For example, Greenland’s annual loss has fluctuated significantly over the past century. And while the Antarctic losses seem stupendously large, the recent annual losses amount to 0.001% of the total ice and, if they continued at that rate, would raise sea level by only 3 inches over 100 years."

"Two recent studies reported in the media focus on the terminus of glaciers—i.e., where the ice, the ocean and the ground come together. One study used an underwater drone to map the seabed at a depth of 2,000 feet, about 35 miles from the terminus of the Thwaites Glacier in Antarctica. Detailed sonar scans showed a washboard pattern of ridges, most less than 8 inches high. The ridges are caused by daily tides and serve as a record of where ice touched the seabed in the past. Researchers could read that record to infer that at some time in the past the glacier retreated for half a year at more than twice the fastest rate observed between 2011 and 2019."

"a connection between ocean currents and discharge would increase the overall discharge rate in one region of the continent by some 10% by the end of the century. But to emphasize the idea being tested, the modelers used human influences almost three times larger. Even though that fact is stated in the paper, reporters rarely catch such nuance, and the media goes with headlines such as “Antarctic Ice Melting Could Be 40 Percent Faster Than Thought” with the absurd statement that “a massive tsunami would swamp New York City and beyond, killing millions. London, Venice and Mumbai would also become aquariums.” A more accurate headline would read: “Ocean currents connecting antarctic glaciers might accelerate their melting.”"