But what specialists have much less data on is how these very important glaciers have modified prior to now, notably within the centuries earlier than satellite tv for pc information existed. Understanding how glaciers have responded to previous adjustments in local weather can affect projections scientists make about how they could reply to future warming.
The researchers discovered that Greenland’s glaciers are very delicate to local weather circumstances, and have misplaced ice within the late-Nineteenth and early-Twentieth century at charges that rival or surpass these seen as we speak. With the planet — and the Arctic specifically — anticipated to heat a lot more this century, the scientists warn their findings present that ice loss on Greenland could exceed even the worst-case projections.
David Holland, a professor of arithmetic and environmental science at New York University and a co-author of the examine, mentioned the staff’s findings present that the Arctic “is undergoing a one-two punch with respect to the loss of its land and sea ice covers in a warming world.”
Using historic images of the Jakobshavn, Helheim and Kangerlussuaq glaciers, the staff calculated ice loss from 1880 to 2012. They estimated that the quantity of ice misplaced from these three glaciers alone resulted in a sea level rise of 8.1 millimeters. Holland mentioned that whereas the three glaciers are necessary in their very own proper, in addition they function proxies for nearly all of the opposite outlet glaciers in Greenland, giving scientists a glimpse at how the complete ice sheet behaves.
Greenland’s ice sheet is a dynamic place that’s continually shifting and shifting. If we consider the inside of the ice sheet as a mountain lake, Moon says, these outlet glaciers are the streams fanning out from the lake, carrying ice away from it and in lots of instances, into the ocean. When ice breaks off from the glacier and lands within the ocean, it raises sea ranges.
“These three glaciers are among the fastest moving in Greenland. When we think about these glaciers all around the edge of Greenland acting like conveyor belts (moving ice towards the ocean), these are some of the fastest, largest conveyor belts on the ice sheet,” mentioned Twila Moon, deputy lead scientist on the National Snow and Ice Data Center in Boulder, Colorado, who wasn’t concerned within the examine.
The glaciers additionally maintain sufficient ice to lift international sea ranges by roughly 1.3 meters.
Ice loss over time is pushed by pure shifts in winds and ocean currents, and when heat waters get close to the glaciers, they soften, Holland says. But human-caused warming has altered the local weather and is altering how the winds and ocean work together with the ice sheet, and due to this fact influencing the quantity of ice loss.
The staff discovered that charges of ice loss for the Jakobshavn Glacier within the early 1900s had been similar to the massive charges of loss seen as we speak, and for the Kangerlussuaq Glacier, ice loss between 1880 and 1930 was really bigger than current day.
That’s vital as a result of it reveals that the glaciers had been dropping massive quantities of ice at a time when international temperatures had been decrease than they’re now.
Under a worst case-scenario by which people proceed to lift concentrations of those heat-trapping gases within the ambiance, the planet could heat by 3.7 levels Celsius (6.66 levels Fahrenheit) by the top of this century.
If the glaciers have already suffered massive ice losses when atmospheric and ocean temperatures had been decrease — and the planet is ready to heat even more underneath a high-emissions future — the scientists say their findings could imply fashions used to foretell future ice loss in Greenland could be underestimating how a lot will likely be misplaced by the top of the century.
That could additionally affect present projections of sea level rise.
“I think when it comes to the pace of change in Greenland and really with ice everywhere in the world, we’re already at five-alarm status,” mentioned Moon. “And this paper is one more paper in that monstrous pile that says these are really serious changes, they’re happening very quickly and we we need to be taking action as soon as possible so that we can try to reduce the rate of change in the future.”
In the examine, the scientists mentioned that the potential underestimation of ice loss is probably going “not limited to just these three glaciers,” and that it was necessary that fashions seize fast glacial retreat because of human-induced warming of our oceans and ambiance “as they are the primary driver of mass loss.”
The staff hopes their findings on how glaciers are delicate to adjustments within the local weather will assist enhance the reliability of future projections of ice loss.
“The Arctic is losing ice, and as you look in greater detail over the last century, you see periods of more loss and less loss, but always loss,” Holland mentioned. “With increased warming projected to continue into the future, increased ice loss can be expected with potentially serious negative consequences for coastal cities around the world.”
CNN’s Ivana Kottasova contributed to this report.