As the oceans warm, marine life is threatened with extinction comparable to that of the dinosaurs

(ORDO NEWS) — By 2100, we could face a loss of life in the oceans equal to the largest extinctions in Earth’s history – if we don’t continue to fight the climate catastrophe, new modeling warns.

But “it’s not too late to take the steps to reduce greenhouse gas emissions needed to avoid a major extinction event,” Princeton geoscientists Justin Penn and Curtis Deutsch explain in their paper.

Using simulations calibrated against ancient fossils, they predict the effects of abrupt climate change on marine life and offer a plausible explanation for one of the ocean’s mysteries.

Scientists have found that we are repeating a similar pattern seen during the “great extinction” 252 million years ago, when volcanoes spewing greenhouse gases along with microbes spewing methane rapidly increased the temperature on Earth, wiping out up to 90 percent of all marine animal species.

As we continue to release fossil fuel exhaust gases into the atmosphere, excess heat changes the ocean’s chemistry and reduces its ability to hold oxygen.

The new study takes into account the well-studied relationship between oxygen, temperature, and the physiological limitations of various species; the findings suggest that the current warming trajectory will lead to a mass extinction on a scale not seen since the extinction of the non-aviation dinosaurs.

And this is without taking into account subsequent changes in the chemical composition of the marine environment – ocean acidification, which will lead to the extinction of even more species.

Today’s warming is already driving marine life towards colder seas, globally lowering ocean oxygen levels, bleaching reefs, destroying kelp forests and, in strange blobs of warm water, suffocating masses of animals to death.

“Climate change is essentially taking species away from the ends of the Earth,” Rutgers University ecologists Malin L. Pinsky and Alexa Fredston explain in their review article for the journal Science Perspectives.

Although climate change is now the fifth most devastating threat to ocean life after overfishing, transport, development and pollution, by the end of the century it will eclipse all direct human threats combined.

The tropical regions and upwelling systems of the North Pacific, which are super productive today, are already close to the limits due to low oxygen content. These areas currently provide about 20 percent of humanity’s dietary protein.

But polar species will suffer the most.

“Species native to the tropics can tolerate warm, low-oxygen waters, making them resilient to the climatic expansion of these conditions, especially for species with a high colonizing capacity,” write Penn and Deutsch.

“In contrast, polar species occupy a disappearing climatic niche and have no refuge as the climate warms.”

In the modern world, the number of different species of animals in the oceans is increasing from the poles to the tropics, but near the equator there has long been a mysterious decline.

The data from these models, as well as paleontological data, suggest that the reason for this decline in biodiversity is that many species here reach their temperature-dependent hypoxia limit.

“The extent of the extinction that we have found is highly dependent on how much carbon dioxide [CO2] we release into the atmosphere going forward,” explains Penn.

“There is still enough time to change the trajectory of CO2 emissions and prevent warming that will cause a mass extinction.”

They calculated that if we manage to limit warming to 2°C by 2100, we can reduce species extinction by more than 70 percent compared to the worst-case scenario (8.2°C).

Even limiting warming to 2.6°C would keep the impact of climate change on our oceans smaller than more direct threats. But these scenarios require us to make real big changes.

Fortunately, we are now on track to avoid the worst-case scenario with current mitigation policies and lower-than-forecast economic growth.

As with any model of complex systems, it leaves many uncertainties – for example, how much habitat, on average, a particular marine species can lose before it goes extinct.

In addition, the model only uses physiological data from a dozen species representing marine life, so adding them would increase the accuracy of the model.

But when you consider that it accurately explains the fossil record when the team used it to model the Great Dying, as well as the catastrophe we are already witnessing, then the general conclusion can be considered correct.

Obviously, in order to keep the liquid world, which covers 70 percent of our planet, thriving with life, we must contend with both the immediate threats to which it is exposed from our side, from pollution to overfishing, and the more serious threat, which we present as a result of human-induced climate change.

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