Monday, October 12, 2015

This is how rising seas will reshape the face of the United States

[Washington Post] Millions of Americans live on land destined to be reclaimed by rising sea levels, and that number rises dramatically if carbon dioxide emissions continue unchecked or if West Antarctica’s ice sheet is as unstable as recent studies suggest, according to a new report.
The striking result is that millions of Americans may already live on land destined to be someday — albeit perhaps in a very distant future — reclaimed by the sea. But the number for whom this is true will rise dramatically if carbon dioxide emissions continue unchecked — or, if recent concerns about the destabilization of the ice sheet of West Antarctica turn out to be well founded.
“Future emissions will determine which areas we can continue to occupy or may have to abandon,” note the report’s researchers, led by Benjamin Strauss of Climate Central in Princeton, N.J. The work appeared Monday in the Proceedings of the National Academy of Sciences and was co-authored by Scott Kulp of Climate Central and Anders Levermann of the Potsdam Institute for Climate Impact Research in Germany.
The analysis, “Carbon choices determine US cities committed to futures below sea level,” turns on a critical number: For every one degree Celsius of warming, the scientists estimate that we should expect 2.3 meters of long-term, eventual sea-level rise, playing out over millennia. That calculation is based on much research and represents the “state of the art,” said Stefan Rahmstorf of the Potsdam Institute, who was not involved in the study but has published previously with Levermann. “It is the best estimates we can make with the understanding that we have today about the processes leading to sea-level rise.”
The authors do not say how fast the sea-level rise could occur — the basic assumption is that the estimate of 2.3 meters plays out over 2,000 years, as the planet’s huge masses of ice slowly adjust to a change in its temperature. But much of the sea-level rise could happen a lot faster than that. Its precise timing is a key question for scientific inquiry right now. Read More