National Parks Could Change Forever

A third of all glaciers, including those that adorn many U.S. national parks, will be obliterated this century even if global warming was halted today, a new study says. 

Using glacier models and data from Randolph Glacier Inventory, researchers from Germany's University of Bremen and Austria's Innsbruck University studied mountain glaciers outside Antarctica and Greenland and found that the "further melting of glaciers cannot be prevented in the current century — even if all emissions were stopped now," according to a press release.

Ben Marzeion of the University of Bremen and lead author of the study published last week in Nature Climate Change said that about 36 percent of the ice still stored in glaciers today will melt because of past greenhouse gas emissions.

"That means more than a third of the glacier ice that still exists today in mountain glaciers can no longer be saved even with the most ambitious measures," Marzeion said.

Losing a third of ice stored in glaciers also means that sea levels will rise by more than 4 inches, the authors note. 

"Melting glaciers have a huge influence on the development of sea level rise. In our calculations, we took into account all glaciers worldwide — without the Antarctic and Greenland ice sheets and peripheral glaciers — and modeled them in various climate scenarios," Georg Kaser of the Institute of Atmospheric and Cryospheric Sciences at the University of Innsbruck said. 

The authors explain in the study that it can take millennia for glaciers to respond to climate conditions. In other words, there is a gap between the rapid rise in temperatures over the past century and the time it will take for the glaciers to catch up and melt as a result.

They also point out that to preserve the amount of glacial ice that currently exists, the average global temperature would have to drop to pre-industrial levels, something the authors say "is obviously not possible."

(MORE: One of the Largest Icebergs Ever Recorded Breaks Off From Antarctica)

To illustrate the effects of carbon emissions on glaciers, the researchers calculated that every kilogram (2 pounds) of CO2 that is emitted today will result in 15 kilograms (33 pounds) of glacier melt in the long term.

"Calculated on the basis of an average car newly registered in Germany in 2016, this means that one kilogram (2 pounds) of glacier ice is lost every five hundred meters (0.3 miles) by car," Marzeion said.

Kaser said the greenhouse gas emissions from the past have "already triggered changes that can no longer be stopped," but noted that keeping the average mean temperatures to below 1.5 degrees Celcius above pre-Industrial levels, a marker of the Paris Climate Accord, will make a significant difference in preserving the world's glaciers and preventing further sea level rise. 

Gerard Roe of the University of Washington was the lead author of 2016 study that identified shrinking glaciers as “categorical evidence” of human-caused climate change. In response to this latest study, Roe told Carbon Brief that it's further proof that "we really are on course to obliterate many of these mountain landscapes.”