A recent study by a group of researchers now states that the Greenland ice sheet has entered a state of sustained mass loss that is irreversible and will not be able to compensate for the loss of ice, even if global warming were to end soon.
The study looked at 40 years of satellite data and stated that the Greenland ice sheet which covers nearly 80 percent of the vast island contains the equivalent of about 24 feet of global mean sea-level rise and its accelerated retreat is the largest single contributor to rising sea levels worldwide.
The study, led by Michalea King of the Byrd Polar and Climate Research Center found that glacier retreat has pushed the ice sheet to an imbalanced state, suggesting that even if oceans and the atmosphere stop warming, the ice sheet will continue to lose more ice than it will gain.
According to researchers ice lost in a given year is usually replenished by snowfall in winter to maintain the near-constant mass. However, since the beginning of 2000, ice discharged through outlet glaciers has outpaced annual snowfall.
According to King, the shift is like a tipping point that is not likely reversible in the near future.
Ian Howat, director of the Byrd Polar and Climate Research Center and co-author of the paper stated that longer-term thinning throughout the 20th century led to an increase in the rate of discharge through outlet glaciers.
According to study authors, before 2000, 420 gigatonnes of ice were discharged annually. In the years following, the rate increased to 480 gigatonnes of ice discharged annually.
“When all of these glaciers retreated at once, it was enough to significantly increase the rate at which ice flows into the ocean,” Howat said adding that it is like the spillway on the dam being opened up.
According to lead author King, an extra 60 gigatonnes each year of snowfall or reduced melting for the glacier would be needed to return to a balanced state.
The results of the study were published in the scientific journal Communications Earth & Environment on 13 August. It mentions that researchers have found that increased glacier discharge was mostly due to the retreat of glacier fronts rather than an inland ice sheet.
source https://www.firstpost.com/tech/science/greenland-ice-sheet-has-entered-state-of-sustained-mass-loss-study-says-it-is-irreversible-8783761.html
