The research came about because of the fact that scientists still have to reach a consensus on how much and how quickly melting of the Greenland Ice Sheet will contribute to sea level rise.
To shed light on this question, scientists at the University of Wisconsin and Columbia University's Center for Climate Systems Research analyzed the disappearance of the Laurentide Ice Sheet, the last ice sheet to melt completely in the Northern Hemisphere and the closest example of what can be expected to happen to the Greenland Ice Sheet in the next century.
"We have never seen an ice sheet retreat significantly or even disappear before, yet this may happen for the Greenland Ice Sheet in the coming centuries to millennia," said Anders Carlson, the study's lead author and assistant professor of geology and geophysics at the University of Wisconsin-Madison.
"What we don't know is the rate of melting of the Greenland Ice Sheet. The geologic data we compiled on the retreat history of the Laurentide Ice Sheet, however, gives us a window into how fast these large blocks of ice can melt and raise sea level," he added.
Analyzing geologic data and computer models, the team of researchers used terrestrial and marine records to reconstruct the demise of the Laurentide Ice Sheet, a land-based ice mass that covered much of North America, until its ultimate disappearance at around 6,500 years ago.
The ice sheet, which once covered most of Canada and the upper reaches of the United States, had two intervals of rapid melting, the first around 9,000 years ago, and the second 7,500 years ago.
The researchers estimate that around the time of the first melting phase, the retreating ice sheet led to about approximately 7 meters of sea level rise at about 1.3 cm a year. The second phase accounts for around 5 meters of sea level rise at about 1.0 cm a year.
These rates are comparable to evidence for global sea level rise for this interval derived from coral records.
"I was surprised to see that the model-in agreement with Anders' data-showed the Laurentide Ice Sheet disappearing at 2.7 m/year," said Allegra LeGrande, who led the computer modeling portion of this study and is a postdoctoral research scientist at the NASA Goddard Institute for Space Studies and the Center for Climate Systems Research at Columbia University.
"This finding shows the potential for ice to disappear quickly, given the right push," she added.