At the current rate, Greenland will lose its ice sheet forever

In a new study from the University of Reading, experts have found that global warming will lead to irreversible melting of the Greenland ice sheet. As the massive ice sheet steadily declines, it is approaching a tipping point at which it will no longer be able to bounce back – and will permanently alter sea levels worldwide.

“During 1961–1990 the Greenland ice sheet had a roughly constant mass, in which snowfall was balanced by the sum of surface ablation (meaning all processes of mass loss, predominantly liquid run-off due to melting) and solid discharge of ice into the sea,” wrote the study authors. “Over the last 30 years both ablation and discharge have increased significantly, while snowfall has not.”

According to the researchers, under scenarios in which global warming goes beyond two degrees Celsius, we can expect significant ice loss and several meters of global sea level rise to persist for tens of thousands of years.

Even if temperatures were to eventually fall, the scientists have shown that the Greenland ice sheet will never fully rebound once it melts beyond a critical point. At this tipping point, sea levels will be permanently two meters higher than they are now, regardless of other factors contributing to sea level rise.

The experts identified some scenarios in which the ice sheet melting could be reversed,  but they rely on urgent action to address global warming. 

The Greenland ice sheet is seven times the area of the UK. At the current rate of decline, ice lost from Greenland results in about one millimeter of sea level rise each year. Despite some seasonal gains, the ice sheet has lost three and a half trillion tons of ice since 2003.

To investigate the future of the ice sheet, the scientists used a computer model that combines climate and ice-sheet models to simulate potential temperature rise. Under all of the climates that were like today or warmer, the ice sheet declined in size and contributed to sea-level rise to some degree.

“Our experiments underline the importance of mitigating global temperature rise,” said study lead author Professor Jonathan Gregory. “To avoid partially irreversible loss of the ice sheet, climate change must be reversed – not just stabilized – before we reach the critical point where the ice sheet has declined too far.”

The study is published in the journal The Cryosphere.

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By Chrissy Sexton, Earth.com Staff Writer