A new report shows that the glaciers that comprise Greenland’s ice sheet have melted so much that no matter what we do, they are destined to disappear. The tipping point has come about because snowfall can not keep up with rapidly melting ice.
Point of No Return
The Greenland ice sheet is a spread of glacial ice that covers just under 80% of the surface of the country. This ice has always melted into the ocean at a rate—known as its “pulse”—that has been balanced by replenishment from snow. However, looking at 40 years of monthly satellite data from more than 200 large glaciers draining into the ocean, Ohio State University researchers have determined that the ice sheet is melting faster than it can be replenished. This, they believe, has caused it to reach a point of no return in which the sheet will continue to dissolve, no matter what humans do to reverse or stem global warming.
This is particularly bad news for coastal cities. Last year, the world’s oceans rose by 2.2 mm in only two months thanks to the melting ice sheet. Should the entire sheet dissolve into the ocean, sea levels will rise by as much as 23 feet according to NASA, and the rotation of the earth would actually slow ever so slightly, making our days longer by about two milliseconds.
One in a Hundred
Historically, the glaciers that form the ice sheet discharged about 450 gigatons of ice into the oceans each year, with that discharge replenished by snowfall. Each year, the glaciers would gain or lose mass depending on environmental conditions. The researchers found that ice melt began to accelerate in 2000, with glaciers discharging about 500 gigatons of ice into the oceans each year with no accompanying increase in snowfall. They’ve concluded that now, the ice sheet can only gain mass in one out of every 100 years—not enough to stem their demise.
The ice loss has created something of a feedback loop. As the glaciers melt, more seawater can flow across the ice sheet, get heated by the sun, and dissolve even more glacial mass. That’s why the researchers feel that regardless of any changes to the environment, the ice sheet is doomed.
“Glacier retreat has knocked the dynamics of the whole ice sheet into a constant state of loss,” said Ian Howat, a co-author on the paper and professor of earth sciences Ohio State. “Even if the climate were to stay the same or even get a little colder, the ice sheet would still be losing mass.”
According to NASA, which helped fund the study, at the current rate of melt, sea levels are due to rise 3-5 inches in the next 80 years.
Despite the bad news, the researchers tried to put a positive spin on their findings, which have been published in the peer-reviewed journal, Communications Earth & Environment.
“It’s always a positive thing to learn more about glacier environments because we can only improve our predictions for how rapidly things will change in the future,” said Michalea King, lead author of the study and a researcher at The Ohio State University’s Byrd Polar and Climate Research Center. “And that can only help us with adaptation and mitigation strategies. The more we know, the better we can prepare.”