Researchers from the Geological Survey of Denmark and Greenland observed changes in ice-sheet volume in and around Greenland and saw that meltwater runoff has been the primary driver. Using “well-established theory,” the scientists were able to determine that around 3.3% of the Greenland ice sheet — equivalent to 110 trillion tons of ice — will inevitably melt as the ice sheet reacts to the changes that have already occurred.
The sea level rise from this melted ice will occur “regardless of any foreseeable future climate pathway this century,” according to lead author Jason Box, a scientist with the Geological Survey of Denmark and Greenland. “This water is technically already under the bridge.”
While the authors did not specify a timeline, they predict that the change in sea levels can occur between now and the end of the century.
The research was solely to estimate a minimum, or “a very conservative lower bound,” of sea level rise from melting in Greenland, “and in the virtually-certain event that climate continues warming, the sea level commitment only grows,” Box said.
Massive ice sheets can melt rapidly when the air temperature is warm, but warmer ocean water is also eroding the sheet around the edges.
Greenland holds enough ice that if it all melted, it could lift sea levels by roughly 25 feet around the world. Researchers point out that a sea level rise of 20 feet doesn’t mean it will rise evenly around the globe, leaving some places devastated as the sea level falls in others.
As places such as Greenland lose ice, for example, they also lose the ice’s gravitational pull on water, meaning Greenland’s sea level is falling as the level rises elsewhere, said William Colgan, senior researcher at the Geological Survey of Denmark and Greenland. The rate of that change is the problem, Colgan told CNN’s Bill Weir during a research trip in the summer of 2021.
“It’ll be really hard to adapt to change that fast,” Colgan said, standing at Greenland’s Jakobshavn Glacier, where the fjord is full of ice that has broken off from the glacier.
Before human-caused climate change kicked in, temperatures near 32 degrees Fahrenheit in Greenland were unheard of. But since the 1980s, the region has warmed by around 1.5 degrees per decade — four times faster than the global pace — making it all the more likely that temperatures will cross the melting threshold.
The amount of ice that melted in Greenland between July 15 and 17 alone — 6 billion tons of water per day — would be enough to fill 7.2 million Olympic-sized swimming pools, according to data from the US National Snow and Ice Data Center.
CNN’s René Marsh and Angela Fritz contributed to this report.