Without reduction in greenhouse gases, mass extinction in oceans is possible

Source of hope, limit the global warming to 2 ° C compared to the pre -industrial era would avoid this catastrophe scenario.

Le Monde with AFP

If greenhouse gas emissions are not reduced, the species living in the oceans could be decimated by 2300, Warn a study published Thursday, April 28 in the journal Science. But limit the global warming to 2 ° C compared to the pre -industrial era would avoid this disaster scenario, underline the researchers.

The latter used models analyzing the link between global warming, the decline in the quantities of oxygen in the resulting water, and the quantities of dioxygen (o 2 é>) necessary for the survival of species. Particularly complicated to study, such projections of the risks of extinction in the oceans had so far been very little formulated.

Now the results are alarming: if the greenhouse gas emissions warming the planet continue to increase, then the oceans could experience mass extinction comparable to that of the permien. During this catastrophic event, marine biodiversity had been reduced to its strict minimum, under the combined effect of an increase in temperatures and a decline in oxygen in the oceans, a scenario also underway today.

a source of hope

According to this scenario, the tropical oceans would lose the most species, but many species of these areas migrate to other regions to survive. The polar species would disappear massively, having no place to take refuge.

Source of hope, a scenario limiting warming to 2 ° C would make it possible to “reduce the severity of extinctions by 70 %, avoiding mass extinction”, according to the study.

The Paris Agreement, an international reference text, sets the objective of containing the global warming “clearly below 2 ° C compared to the pre -industrial levels”, and if possible at + 1.5 ° C . This objective is “out of reach” with current international commitments, according to the intergovernmental group of experts on the evolution of the UN climate.

“Because marine extinctions have not progressed as much as those on earth, our society has time to reverse the steam in favor of life in the oceans”, however wrote scientists in a commentary article accompanying study. “Where exactly is our future between the best and the worst scenario will be determined by the choices of society made,” they added.