For decades, the inevitability of many feet, even yards, of sea-level rise in a warming climate has been crystal clear. But society’s response, both in stemming heat-trapping greenhouse gas emissions and adapting to eroding coastlines, will always be more a function of the rate of change than the ultimate outcome.
That’s why it’s important to get beyond headlines — including the titles of papers — in considering new research pointing to the inevitable “collapse” of ice sheets in West Antarctica. To the public, collapse is a term applied to a heart attack victim on a street corner or a building stricken by an earthquake or bomb. To a glaciologist, it describes the transition to unavoidable loss of an ice sheet — a process that can take centuries to get into gear, and millenniums[sic] to complete.
Some headlines are completely overwrought — as with this NBC offering: “West Antarctic Ice Sheet’s Collapse Triggers Sea Level Warning.” This kind of coverage could be interpreted to mean there’s an imminent crisis. It’s hard to justify that conclusion given the core findings in the studies.
Take the Science paper: “Marine Ice Sheet Collapse Potentially Under Way for the Thwaites Glacier Basin, West Antarctica.” Using ice-flow models and observations, the researchers, led by Ian Joughin of the University of Washington, concluded:
Except possibly for the lowest-melt scenario, the simulations indicate that early-stage collapse has begun. Less certain is the time scale, with the onset of rapid (>1 mm per year of sea-level rise) collapse in the different simulations within the range of 200 to 900 years.
To translate a bit, that means sometime between 200 and 900 years from now the rate of ice loss from this glacier could reach a volume sufficient to raise sea levels about 4 inches (100 millimeters) a century. At that point, according to the paper, ice loss could pick up steam, with big losses over a period of decades.* But in a phone conversation, Joughin said the modeling was not reliable enough to say how much, how soon.
“Collapse is a good scientific word,” he told me, “but maybe it’s kind of a bad word” in the context of news.
