Thinning Greenland ice sheet could mean rising sea levels: study

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Part of Greenland’s ice sheet is thinning further inland than previously thought, which will likely lead to greater sea level rise by the end of this century, according to a researcher. new study published on Wednesday.

The findings relate to a northeast section of the giant ice floe cover, but the trend is likely occurring elsewhere on Greenland and Earth’s other ice sheet, Antarctica.

The implications are worrying, as rising sea levels are already threatening millions of people living along coasts who could find themselves underwater in decades and centuries to come.

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Scientists have previously focused on the edges of the Greenland Ice Sheet to examine active melting as global temperatures rise, largely using satellite data.

But the authors of Wednesday’s study looked further inland, more than 100 kilometers from the coast.

What they found was alarming: Greenland’s coastline was thinning for 200 to 300 kilometers (125 to 185 miles).

“What we see happening at the front goes way back to the core of the ice sheet,” first author Shfaqat Abbas Khan said in a press release about the study, published in Nature.

“The new model really captures what’s happening inland, the old ones don’t (…) you end up with a completely different mass change, or sea level projection,” said he told AFP in an interview.

The researchers set up GPS stations on the ice sheet to gather more precise information, and also used satellite data and numerical modeling, all of which provided a new set of data that could change global sea level rise projections. of the sea.

The research was conducted at the Northeast Greenland Ice Stream (NEGIS), which covers around 12% of Greenland, according to co-author Mathieu Morlighem.

He found that the thinning could add between 13.5 and 15.5 millimeters to sea level by the end of this century, equivalent to the contribution of the entire Greenland ice sheet over the of the last 50 years.

“NEGIS could lose six times more ice than existing climate models estimate,” the report said.

One of the reasons for the thinning inland is the intrusion of warm ocean currents which in 2012 caused the collapse of the floating extension of NEGIS.

This event “accelerated the ice flow and triggered a wave of rapid ice thinning that spread upstream.”

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The Greenland Ice Sheet is currently the biggest contributor to Earth’s ocean swelling, according to NASA, with the Arctic region warming at a faster rate than the rest of the planet.

In a landmark report on climate science last year, the Intergovernmental Panel on Climate Change (IPCC) said the Greenland Ice Sheet would contribute up to 18 centimeters to sea level rise. the sea by 2100 in the highest emissions scenario.

The massive two-kilometre-thick ice cap contains enough frozen water to lift the world’s seas by more than seven meters (23 feet) in total.

The researchers will now expand their methods to look at other glaciers in Greenland and Antarctica, and new data could be available in about a year.

The Earth’s surface has warmed, on average, by almost 1.2 degrees Celsius since pre-industrial times, triggering a catalog of impacts ranging from heat waves to more intense storms.

Under the Paris climate agreement, countries agreed to limit warming to well below 2°C.

World leaders are currently meeting in Sharm el-Sheikh, Egypt, for UN climate talks aimed at cutting harmful emissions and increasing funding for green economies in developing countries.

Khan said Greenland’s ice sheet thinning trend will be nearly impossible to reverse, but can at least be slowed with the right policies in place.

“I really hope they agree on a CO2 reduction and as soon as possible,” he said in a message to leaders during the COP27 climate talks.

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