Three recent studies on the West Antarctic Ice Sheet (WAIS) are making waves in the media, re-stoking fears of catastrophic sea-level rise, and putting a spring in the step of many a carbon-taxer.
Thomas Sumner summarizes two of the studies in a Science magazine commentary titled “No Stopping the Collapse of the West Antarctic Ice Sheet.” The studies, he writes, conclude that:
Thwaites Glacier, a keystone holding the massive West Antarctic Ice Sheet together, is starting to collapse. In the long run, they say, the entire ice sheet is doomed. Its meltwater would raise sea levels by more than 3 meters.
Specifically, Joughin et al., writing in Science, find that “in as few as 2 centuries Thwaites Glacier’s edge will recede past an underwater ridge now stalling its retreat. Their models suggest that the glacier will then cascade into rapid collapse.” Rignot et al., writing in Geophysical Research Letters (GRL), “describes recent radar mapping of West Antarctica’s glaciers and confirms that the 600-meter-deep ridge is the final obstacle before the bedrock underlying the glacier dips into a deep basin.”
In addition, McMillan et al., also writing in GRL, report that Antarctica as a whole is losing about 159 billion tons of ice per year. That’s an amount larger than previous estimates and translates to an overall sea-level rise contribution of 0.45 mm/year (1.7 inches per century).
The first two studies expressly conclude that the Thwaites and neighboring outlet glaciers have retreated to a point of no return and that, once gone, nothing can prevent the rest of the WAIS from flowing into the sea.
My initial reaction was: What’s really new here?
Conway et al. (1999), a study of the relentless retreat of the WAIS grounding line since the early-to-mid Holocene (i.e. 9,000 years ago or more), and Bindschadler (2006), a study of the inexorable melting of submarine glaciers in contact with warm ocean currents, both concluded that the WAIS is doomed.*