Climate change: Greenland's ice has melted past the point of no return

Rodiano Bonacci
Agosto 15, 2020

In Greenland, shrinking glaciers are posing an issue to the whole planet.

The Greenland ice sheet would go on shriking even if global warming ended immediately, according to a study using nearly four decades of satellite data.

This has let the glaciers retreat to such an extent they are now melting faster - making it harder for them to grow back to their previous, more stable positions.

"We've been looking at these remote sensing observations to study how ice discharge and accumulation have varied", said Michalea King, a researcher at Ohio State University's Byrd Polar and Climate Research Center and a lead author of a study published Thursday in the journal Nature Communications Earth and Environment.

'What we've found is that the ice that's discharging into the ocean is far surpassing the snow that's accumulating on the surface of the ice sheet'. This means that if the climate crisis were to end today, the ice sheet would continue to shrink because the amount of snow fall each year is less than the amount of melted ice flowing into the ocean each year.

In their study, Ms King and colleagues analysed monthly satellite data on more than 200 large glaciers that are draining into the ocean around Greenland. Over those years, the team discovered that the ice sheets usually lost around 450 gigatons (that is, approximately 450 billion tons) of ice annually from the flowing outlet glaciers, which was substituted with snowfall.

The team found that, during the 1980s and 1990s, the loss of ice by melting from or calving off of the glaciers were broadly balanced out by the accumulation of snow on the icy bodies. "We are measuring the pulse of the ice sheet-how much ice glaciers drain at the edges of the ice sheet-which increases in the summer".

'Glaciers have been sensitive to seasonal melt for as long as we've been able to observe it, with spikes in ice discharge in the summer, ' Ms King said.

King points out that large glaciers across Greenland have retreated about 3 kilometers (1.9 miles) on average since 1985-"that's a lot of distance", she said.

Prior to 2000, the ice sheet would have roughly the same possibility to lose or gain mass every year.

Even though the retreat of the Greenland Ice sheet likely can not be reversed, it's just the first in a series of tipping points.

Greenland's ice largely contributed to sea-level rise-in 2019, sufficient amounts of ice broke off or melted from the Greenland ice sheet and caused the oceans to increase by 2.2 mm in just a period of two months.

"There's a lot of places, like in Florida especially, where one meter alone would cover a lot of existing land areas", King said.

This, she added, can only help us with adaptation and mitigation strategies.

"We've passed the point of no return but there's obviously more to come", Howat said.

This study was financially supported by grants from NASA. Other Ohio State scientists who worked on this study are Salvatore Candela, Myoung Noh, and Adelaide Negrete.

The study used four decades of satellite data to measure changes in Greenland's ice sheet.

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