Even the 1.5-degree Celsius target in the Paris Agreement, which most scientists now say is likely an impossible reach, would be “too high” for the ice sheets survival. And in fact, even the current degree of warming, of about 1.2 degrees C above preindustrial levels, “if sustained, is likely to generate several metres of sea-level rise over the coming centuries, causing extensive loss and damage to coastal populations.” That’s from US and UK researchers, writing in the journal Communications Earth & Environment, this week. It’s not great.
They combined several lines of research, and attempted to answer the question of what, exactly, is a “safe limit” for the ice sheets. The result: it’s probably behind us, more in the range of 1.0 degrees C of warming or so.
At that level, we could probably avoid a rapid acceleration of sea level rise, where rates exceed about one centimeter per year. Beyond that rate, things get hairy, and we’d be looking at “displacing hundreds of millions of people and causing loss and damage well beyond the limits of adaptation.” The 1.0-degree limit is consistent with what scientists were calling for three or four decades ago, when keeping the carbon dioxide in the atmosphere to 350 ppm was a semi-reasonable goal; it’s across 420 ppm now.
In short, the ice is on its way out, and without a truly remarkable reversal the type of sea level rise people imagined might occur in some distant millennium is on its way in — soon. And when that starts happening? From one of the study’s authors, according to The Guardian: “You’re going to see massive land migration on scales that we’ve never witnessed in modern civilization.”
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