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Sunday, September 20, 2020

Explained: How the world’s second largest ice sheet in Greenland melted ‘past point of no return’

The study published by a team of researchers from the Ohio State University, suggests that the glacier is melting at such a rapid rate that the annual snowfall is not enough to replenish it anymore.

By: Explained Desk | New Delhi | Updated: August 27, 2020 4:21:28 pm
Greenland ice sheet, greenland glacier melting, global warming glaciers melting, greenlanc ice sheet melting study,Once the ice sheet melts completely in less than a hundred years, sea levels will rise drastically — leaving coastal cities across the globe completely submerged. (Markus Rex/Alfred Wegener Institute via AP)

The world’s second largest body of ice, the Greenland Ice Sheet, is melting at an unprecedented rate due to rising temperatures induced by climate change, and may now be past the point of no return, a recent study has warned.

The study published by a team of researchers from the Ohio State University, suggests that the glacier is melting at such a rapid rate that the annual snowfall is not enough to replenish it anymore. Even if climate change is somehow contained, the Greenland Ice Sheet will continue to lose ice.

“We’ve passed the point of no return but there’s obviously more to come,” Ian Howat, a co-author of the study and a professor at Ohio State University, told CNN. “Rather than being a single tipping point in which we’ve gone from a happy ice sheet to a rapidly collapsing ice sheet, it’s more of a staircase where we’ve fallen off the first step but there’s many more steps to go down into the pit.”

Once the ice sheet melts completely in less than a hundred years, sea levels will rise drastically — leaving coastal cities across the globe completely submerged.

How was the study conducted?

The team of researchers analysed 40 years-worth of monthly satellite data from more than 200 large glaciers across Greenland’s ice sheet, which are currently melting and draining into the ocean around the country.

The researchers measured the amount of ice that broke off from Greenland’s glaciers and ice shelves to form icebergs, floating freely in the ocean. They also observed the total amount of melted ice that directly mixed with the ocean water.

Greenland ice sheet, greenland glacier melting, global warming glaciers melting, greenlanc ice sheet melting study, A woman stands next to an antenna at an NYU base camp at the Helheim glacier in Greenland. (AP Photo: Felipe Dana, File)

They went on to measure the amount of snowfall received in the region, each year — to assess the extent to which the glaciers were replenished after large swathes of ice were lost.

“We’ve been looking at these remote sensing observations to study how ice discharge and accumulation have varied,” Michalea King, lead author of the study and a researcher at Ohio State University’s Byrd Polar and Climate Research Center, said in a press release.

“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,” she added.

What were the major findings of the study?

In the period between 1980 and 1990, researchers found that snowfall was largely able to replenish the amount of ice lost from the melting of glaciers — maintaining a delicate balance. During this time, ice sheets lost around 450 gigatons (about 450 billion tons) of ice each year, which was then recharged by ample snowfall.

“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,” King explained in the press release. “And what we see is that it was relatively steady until a big increase in ice discharging to the ocean during a short five- to six-year period.”

Greenland ice sheet, greenland glacier melting, global warming glaciers melting, greenlanc ice sheet melting study, Crevasses form on top of the Helheim glacier near Tasiilaq, Greenland (Reuters Photo: Lucas Jackson, File)

It was only at the turn of the century, in the year 2000, when the amount of ice being lost annually began increasing. At this point, the ice sheet started to lose around 500 gigaton of ice each year. While the amount of snowfall remained the same, temperatures continued to soar, causing Greenland’s Ice Sheet to shrink faster than it was being replenished.

Since 1985, Greenland’s many glaciers have retreated about 3 km on an average. “That’s a lot of distance,” King pointed out. Due to this, many of them are now floating in the water as icebergs — the warm water causes the glacier ice to melt further, making it difficult for it to return to its previous location.

“Glacier retreat has knocked the dynamics of the whole ice sheet into a constant state of loss,” Howat said. “Even if the climate were to stay the same or even get a little colder, the ice sheet would still be losing mass.”

Given the sweltering heat caused by rising temperatures over the last two decades, researchers believe that Greenland’s Ice Sheet will only be able to gain mass once every hundred years or so.

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What is causing temperatures to rise at such a rapid rate?

A study conducted in 2019 by a team of researchers from the University of Bern in Switzerland, found that global temperatures in the 20th century were rising at a higher rate than seen in over 2,000 years.

The study showed that climate change during recent centuries was not caused by random fluctuation, but instead by anthropogenic emissions of CO2, as well as other greenhouse gases.

With increased human activities — like burning fossil fuels, deforestation and farming — during and after the industrial age, the rise in temperature has become more marked.

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What does this mean in the long run?

Currently, the ice sheet is already the single greatest contributor to the rise in sea levels worldwide — with over 280 billion metric tonnes of melting ice flooding the ocean every year. Greenland’s ice sheet could melt completely by the year 3000, resulting in a 23-feet rise in sea levels across the planet, according to a Business Insider report.

Due to melting glaciers, the sea level rises by more than a millimetre each year. Climate change is accelerating this phenomenon to a point where researchers fear that the world’s heaving oceans could potentially wash away a huge chunk of coastal land, CNN reported.

According to Michaela King, the loss of ice over the years has been so monumental, that it has caused a change in the gravitational field over the country. After melting or breaking off from Greenland’s ice sheets, the frigid ice is carried by the Atlantic Ocean and then brought to the other oceans of the world.

However, King points out that the grim predictions and realities presented in her study also provide an opportunity to explore the science behind the world’s glacial environments further.

“It’s always a positive thing to learn more about glacier environments, because we can only improve our predictions for how rapidly things will change in the future,” she said. “And that can only help us with adaptation and mitigation strategies. The more we know, the better we can prepare.”

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