Watch for collapsing ice sheets

For all the turmoil in Washington, the single most interesting recent item I read was a News and Comment story in Science about something that happened 125,000 years ago. During a 13,000-year interlude of warming between two ice ages, temperatures were only slightly higher than they are today. Nevertheless an Antarctic ice shelf fell into the sea.

By the end of the period, sea levels around the world were 6 to 9 meters higher than today. Why? According to new evidence reported last week at the American Geophysical Union, in Washington, D.C., the West Antarctic Ice Sheet collapsed. Something of the sort is feared possible today.

If you believe the science (and I certainly do), then further evidence of the peril posed by carbon pollution will be forthcoming. A welter of expert testimony and a few hot summers haven’t been enough. A cataclysmic event may be required to galvanize nations, the U.S. in particular, to action. Yes, important discoveries will be made in the decades ahead. But if we don’t act on what we already know, a world of trouble lies ahead.

David Warsh is proprietor of, based in Somerville, Mass.