Marine life is facing an extinction similar to that of the dinosaurs

Selon une nouvelle modélisation réalisée par des géoscientifiques américains, si nous ne continuons pas à nous attaquer à la catastrophe climatique, nous pourrions nous diriger vers une perte de vie dans nos océit des quesés grand sévés’ ex quis de viesé in Earth. But “it is not too late to implement the reductions in greenhouse gas emissions needed to avoid the Great Extinction,” he explained in Article you posted Science Justin Penn and Curtis Deutsch, geologists at Princeton University.

Using modeling calibrated against the ancient fossil record, they predict the consequences of rampant climate change for marine fauna and offer a plausible explanation for the ocean’s continuing mystery in the process.

Geologists have discovered that we are essentially repeating a pattern similar to the one seen during the ‘Great Death’ 252 million years ago, when greenhouse-gas volcanoes and methane-spewing microbes rapidly increased Earth’s temperatures, wiping out up to 90% of all marine organisms. animal species.

As we continue to pump fossil fuel exhaust gases into the atmosphere, the excess heat is altering the ocean’s chemistry and reducing its ability to hold oxygen. The new study takes into account the well-studied relationship between oxygen, temperature, and the physiological limits of different species; The conclusion is that our current warming trajectory will lead to mass extinctions on a scale not seen since the extinction of the non-avian dinosaurs.

And that’s, even without taking into account the other changes in marine chemistry that will follow – ocean acidification – that will make more species disappear.

Today, warming is already pushing marine life toward colder seas, lowering oxygen levels in the oceans globally, bleaching coral reefs, wiping out kelp forests and, at strange points of hot water, choking large numbers of animals to death. “Climate change is causing species extinctions at the ends of the earth,” ecologists Malin L. Pinsky and Alexa Friedstone from Rutgers University explain in their analysis of the Science Perspectives paper.

While climate change currently ranks as the fifth most devastating threat to life in the oceans, after overfishing, transport, development and pollution, by the end of the century it will surpass all direct human threats combined.

The tropics and northern Pacific water systems, which are now very productive, are already close to the limits of low oxygen. These regions currently provide about 20% of humanity’s dietary protein. But the polar species are the hardest hit.

“Species native to the tropics can tolerate warm, low-oxygen waters, making them resilient to climatic expansion of these conditions, especially for species with high colonial capacity,” Ben and Deutsch writes. “In contrast, polar species occupy a climate critically endangered niche and lack refuge when the climate warms.”

In today’s world, the number of different animal species in our oceans is increasing from the poles to the tropics, but there has long been a mysterious basin near the equator. Data from these models, as well as fossil records, suggest that this decrease in biodiversity may be explained by the fact that many species here reach a temperature-dependent hypoxia limit.

The scale of the extinction we’ve seen depends largely on the amount of carbon dioxide [CO2] that we emit in the future,” says Ben. “There is enough time to change the trajectory of carbon dioxide emissions and prevent the scale of warming that might cause this mass extinction. They calculated that if we could limit global warming to 2°C by 2100, we could reduce species extinctions by more than 70% compared to the most unfavorable scenario (8.2°C). Until we limit warming to 2.6°C, the impact of climate change on our oceans will still be less than the immediate threats. But these scenarios require us to make massive changes.

It is clear that for the liquid world that encapsulates 70% of our planet to continue to thrive, we need to address the immediate threats it faces from us, from pollution to overfishing, as well as the greater threat posed by human-caused climate. they change.

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