Startling findings of a new study indicate that melting of ice on Greenland passed a tipping point 20 years ago and some of its glaciers and ice caps could completely vanish by the year 2100.
The study published in the journal Nature Communications notes that some of the smallest glaciers and ice caps are not in a position to regrow any more and this effectively means that they will be lost over the next few decades. The study also indicates that the melting of Greenland’s coastal ice will raise global sea level by about 1.5 inches by 2100.
The study and its findings provide us with a much clear picture as to why some parts of Greenland are melting quickly than the other parts. Researchers behind the study note the deep snow layer that normally captures coastal meltwater was filled to capacity in 1997. That layer of snow and meltwater has since frozen solid, so that all new meltwater flows over it and out to sea. While this is bad news, scientists say it doesn’t create a panic situation as their findings apply to the comparatively small amount of ice along the coast only and not on the Greenland Ice Sheet, which is the second largest ice cache in the world.
Scientists add that these smaller ice caps and the glaciers are doomed and they will vanish over the course of next few decades. The study also points out that as the tipping point was reached in the late 90’s before warming really took off, it indicates that these peripheral glaciers are very sensitive and, potentially, ephemeral relative to the timescales of response of the ice sheet.
According to authors of the study, the problem at Greenland lies between fresh surface snow and the ice, in a layer of older snow called the firn. Normally, meltwater drains through gaps in the firn down to the ice surface, where the bottom layer re-freezes. That’s how glaciers and ice caps grow. When the firn around Greenland’s edges became fully saturated 20 years ago, it froze through from bottom to top. Since then, there haven’t been any gaps to capture meltwater, and the ice hasn’t been able to grow.
At the time, researchers couldn’t have known, because they lacked three things: a high-resolution topographic model of the glaciers, a detailed map of glacier boundaries, and a high resolution numerical model of drainage processes.
Researchers found during the course of their study that for the last 20 years mass loss has been exactly equal to the amount of meltwater runoff lost to sea. Simulations showed that a frozen firn was the most likely cause. The Greenland Ice Sheet is subject to the same danger, but to a much lesser degree than the isolated bits of ice on its edges.