After that we'll be committed to multiple more meters of sea level rise that will occur at rates of up to a meter?or three feet?per one hundred years.

A lot of the stories you read make it sound like there's uncertainty. There's not uncertainty.

Although ice-sheet disintegration and the subsequent sea-level rise lags behind rising temperatures, the process will become irreversible sometime in the second half of the 21st century unless something is done to reduce human emissions of greenhouse-gas emissions.

Although we show that the models do an excellent job, our primary results are based on data. We know the ice sheets melted. We know how much warmth it took to melt them. And that is not a modeled finding.

This is a real eye-opener set of results. The last time the Arctic was significantly warmer than the present day, the Greenland Ice Sheet melted back the equivalent of two to three meters of sea level.

This is a real eye-opener set of results. The warmth necessary to do this isn't all that great.

The results suggest the threshold is close to the end of this century, and it could come sooner. The Arctic is already warming much faster than we thought it would. To think we're not going to get 4 to 5 degrees warmer in another 50 years is wishful thinking.

We need to start serious measures to reduce greenhouse gases within the next decade. If we don't do something soon, we're committed to four to six meters (13 to 20 feet) of sea-level rise in the future.

If we decide to keep on the track we're on now and just keep on warming, because of greenhouse gas pollution, then we could easily cook those ice sheets more rapidly.

Mother Nature is changing even faster than models suggested it would in the Arctic.