Scientists now believe that the Greenland ice sheet may be even more vulnerable to the effects of global warming.
According to a recent study, the coastline glaciers of Greenland are melting more quickly as a result of warmer ocean waters and rising air temperatures.
The research, which was published in the journal Nature Geoscience, provides fresh insight into the factors influencing the second-largest ice sheet in the world's ice loss.
An average of 250 billion metric tons of ice are being lost from the Greenland ice sheet every year. According to studies, there are two key factors that are speeding up these losses over time.
About half of the ice that Greenland loses each year is due to the ice sheet's surface melting as a result of warm air temperatures. The other half is caused by glaciers near the border of the ice sheet calving into the water.
Up until recently, losses from these glaciers by the sea have been primarily attributed to warm ocean waters licking at the ice's edge. However, the latest study discovers that increasing air temperatures also play a significant role.
The ice sheet's surface begins to melt due to warm air, and the melting water eventually drains into the ocean. When that occurs, the turbulence in the water helps heat rise from the ocean's depths and warm the waters that are coming into contact with the ice. The glaciers then melt more quickly as a result.
Donald Slater, a scientist at the University of Edinburgh and the study's lead author, compared the process to ice cubes in a glass of water. When the water is warmer, they undoubtedly melt more quickly. However, stirring the water causes them to melt more quickly.
In a statement, he said that warming air temperatures in Greenland "essentially result in a stirring of the ocean close to the ice sheet, triggering faster melting of the ice sheet by the ocean."
In order to determine the relative contributions of the ocean and atmosphere, the researchers first looked at the rates of glacier melt at Greenland's beachfront glaciers using a mix of measurements and models.
They discovered that south Greenland's glaciers are melting more quickly. These glaciers are the closest to the warm Atlantic Ocean, so that wasn't a surprise. The models indicate that warm waters in these regions are mostly responsible for melting the ice.
On the other hand, because they are exposed to cooler waters, the glaciers in the northern regions of the ice sheet tend to melt more slowly. In these regions, the water still has the greatest influence, although air temperatures are also important.
The study comes to the conclusion that the acceleration of glacier losses from Greenland has been greatly aided by warmer air temperatures. The study concludes that the overall retreat of Greenland's glaciers might have been reduced by as much as a third if the atmosphere hadn't warmed over the last few decades. It might have been cut in northwest Greenland by as much as 50%.
According to Slater, "this regrettably adds to the mountain of evidence demonstrating the Greenland ice sheet's sensitivity to climate change, therefore the necessity for quick action to cut greenhouse gas emissions."