Study predicts mass extinction of marine life if warming continues

By the year 2300, life in the oceans will face mass mortality rivaling the great extinctions of Earth’s deep past if humanity fails to reduce greenhouse gas emissions, according to a study published in the latest edition of the journal Science.

But limiting global warming to two degrees Celsius above pre-industrial levels will avert such a catastrophe, said the paper’s authors, Justin Penn and Curtis Deutsch, both affiliated with the University of Washington and the University of Princeton.

The authors used ecophysiological modeling to weigh the physical limits of species with projected sea temperatures and depletion of oxygen levels, a particularly challenging task given the lack of previous work in the region.

The results were alarming: under “business as usual” warming, the planet’s marine ecosystems could experience a mass extinction comparable to that of the late Permian, known as the “Great Dead”.

It happened 250 million years ago and led to the death of more than two-thirds of marine animals, due to warming and oxygen depletion, conditions similar to those occurring today today.

A polar bear stands on floating ice. /APC

A polar bear stands on floating ice. /APC

While tropical oceans would lose the most species, many of these regions would migrate to higher latitudes to survive.

In contrast, polar species would disappear en masse, since their habitat types would disappear entirely from the planet.

Limiting warming to 2 degrees Celsius, the upper limit of the goal set by the Paris agreement, “would reduce the severity of extinctions by more than 70%, avoiding a marine mass extinction,” the paper said.

The preferred target, limiting warming to 1.5 degrees Celsius, is impossible to achieve with current international commitments, according to UN climate experts.

“Because marine extinctions haven’t progressed as far as those on land, society has time to turn the tide in favor of ocean life,” scientists Malin Pinsky and Alexa Fredston wrote in an accompanying commentary. .

“Exactly where the future stands between the best and worst scenarios will be determined by the choices society makes not only on climate change, but also on habitat destruction, overfishing and coastal pollution. “

(Cover image via CFP)

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Source(s): AFP

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