sea-rise.jpgThis weekend, the AP released the following story:

Global warming — through a combination of melting glaciers, disappearing ice sheets and warmer waters expanding — is expected to cause oceans to rise by one meter, or about 39 inches. It will happen regardless of any future actions to curb greenhouse gases, several leading scientists say. And it will reshape the nation.

Wow! The first amazing thing is the confidence with which AP makes a statement beyond the IPCC’s scientific consensus. This is what most of the experts I spoke to for my book said, and I’m glad to see it in print (kudos to AP reporter Seth Borenstein):

Few of the more than two dozen climate experts interviewed disagree with the one-meter projection. Some believe it could happen in 50 years, others say 100, and still others say 150.

The second amazing thing is this quote:

Even John Christy at the University of Alabama in Huntsville, a scientist often quoted by global warming skeptics, said he figures the seas will rise at least 16 inches by the end of the century. But he tells people to prepare for a rise of about three feet just in case.

Looks like Christy needs to straighten Lomborg out.

The third amazing thing — and the one I (and I think Hansen) would take some exception with — is, “It will happen regardless of any future actions to curb greenhouse gases.” Still, Borenstein gets a stunning quote here:

“We’re going to get a meter and there’s nothing we can do about it,” said University of Victoria climatologist Andrew Weaver, a lead author of the February report from the Intergovernmental Panel on Climate Change in Paris. “It’s going to happen no matter what — the question is when.”

My point — and I think Hansen’s point — is that the “when” (i.e. the rate of change) matters a lot! One meter by mid-century would be an unmitigated catastrophe. Sea level rise would have to average 9 inches a decade from now to 2050, implying seas rising over a foot a decade by then — which could continue for centuries. Who could adapt to that?

Strong actions to limit further emissions starting today — what Hansen calls the alternative scenario — can limit total warming from preindustrial levels to about 2°C, which should keep sea level rise below one meter per century. That’s a disaster, but a slow-moving one, leaving time for some adaptation. And if we were lucky, the rate might be well below a meter per century.

We have only a few years to get on the alternative path, or the one meter of sea level rise is almost sure to come this century.