PARIS, Oct 19, 2023 (BSS/AFP) - Breaching the global warming limits of the
world's climate goals could see the melting of Greenland's ice sheet add more
than a metre to rising sea levels, according to new research on Wednesday.

But the study by an international team of researchers found there would still
be hope to prevent a collapse of the ice sheet -- if warming is reversed and
brought back to the safer level.

The melting of Greenland's vast ice sheet -- the world's second-largest after
Antarctica -- is estimated to have contributed more than 20 percent to
observed sea level rise since 2002.

Rising sea levels threaten to intensify flooding in coastal and island
communities that are home hundreds of millions of people, and could
eventually submerge whole island nations and seafront cities.

A study published in the journal Nature on Wednesday used two models to
simulate how Greenland's ice sheet would respond to future temperature
increases over timescales ranging from hundreds to thousands of years.

Researchers suggested abrupt ice sheet losses would be triggered if global
average temperatures reached a range of 1.7C-2.3C above pre-industrial
levels.

That would risk a permanent "tipping point" that would see near-complete
melting of the Greenland ice sheet over hundreds or thousands of years and
could lift oceans by seven metres (23 feet), redrawing the world map.

But if the temperature increases were rolled back to the Paris deal 1.5C
limit quickly enough -- by removing planet-heating pollution from the
atmosphere using vast reforestation or technologies to capture carbon and
permanently store it -- then the worst could be avoided.

"We found that the ice sheet reacts so slowly to human-made warming that
reversing the current warming trend by cutting greenhouse gas emissions
within centuries may prevent it from tipping," said study co-author Niklas
Boers from the Potsdam Institute for Climate Impact Research.

"Yet, also just temporarily overshooting the temperature thresholds can still
lead to a peak in sea level rise of more than a metre in our simulations."

- Tipping points breached -

Other tipping points in the Earth system may be breached far sooner, the
researchers said, including rainforests and ocean current systems that change
in much shorter timeframes.

"The Greenland ice sheet is likely more resistant to short-term warming" than
previously thought, said Nils Bochow, a researcher at the Arctic University
of Norway and lead author of the study.

But the researchers stressed that returning temperatures to below the "safe"
threshold for the Greenland ice sheet would be far harder than keeping them
below the limit in the first place.

World leaders will gather in Dubai from November 30 for crunch UN talks on
slashing planet-warming greenhouse gas emissions, adapting to and financially
bracing for the impacts of climate change.

Technologies to reduce temperatures on such a vast scale may not exist,
Bochow told AFP.

"We should try everything today to keep the temperatures in a safe range
rather than betting that we can reduce them later," he said.