Greenland’s Nearing a Climate Tipping Point. How Long Warming Lasts Will Decide Its Fate, Study Says

https://insideclimatenews.org/news/23122019/greenland-ice-sheet-climate-tipping-point-temperature-duration-sea-level-rise-pnas-study

By Bob Berwyn, InsideClimate News
Dec 23, 2019

There's new evidence that, in past geologic eras, much of Greenland's ice melted when Earth's temperatures were only slightly warmer than today's, and that human-caused global warming will push the ice sheet past that tipping point in the next few decades.

Exactly how much of the ice melts, and how fast, depends in large part on how long temperatures stay above that threshold, scientists write in a study published Monday in the Proceedings of the National Academy of Sciences.

The findings are a warning that we are probably overestimating the stability of the Greenland Ice Sheet, said University of Bergen paleoclimatologist Ulysses S. Ninnemann, a co-author of the study.

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Sea level rise is not the only reason to be concerned about melting on the Greenland Ice Sheet. There is increasing evidence that the growing discharge of cold, fresh water is also disrupting an ocean current that helps balance the global climate by circulating deep, cold water from polar regions toward the equator.

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A recent study explored how the melting ice sheet may be contributing to a slowdown of the entire circulation system. If it were to slow significantly or collapse, research suggests it would lead to widespread cooling throughout the Northern Hemisphere and large changes in precipitation and strengthening storms.

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