Don’t Believe the Hype About Antarctica’s Melting Glaciers
From Wall Street Journal Opinion/Commentary
Alarming reports that the Antarctic ice sheet is shrinking misrepresent the science under way to understand a very complex situation. Antarctica has been ice-covered for at least 30 million years. The ice sheet holds about 26.5 million gigatons of water (a gigaton is a billion metric tons, or about 2.2 trillion pounds). If it were to melt completely, sea levels would rise 190 feet. Such a change is many millennia in the future, if it comes at all.
Much more modest ice loss is normal in Antarctica. 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.
Many fear that a warming globe could cause glaciers to retreat rapidly, increasing discharge and causing more rapid sea-level rise. To get beyond that simplistic picture, it is important to understand how glaciers have flowed in the past to predict better whether they might flow faster in the future.
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.
Mr. Koonin is a professor at New York University, a senior fellow at the Hoover Institution and author of “Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters.”