Unchecked emissions may lead to marine mass extinction

A new study led by Princeton University has found that, as greenhouse gas emissions continue to warm the world’s oceans, marine biodiversity could plummet within the next few centuries to levels not seen since the extinction of dinosaurs. According to the experts, tropical waters would experience the greatest loss of biodiversity, while polar animal species will be at the highest risk of extinction. However, reversing greenhouse gas emissions could reduce these risks by up to 70 percent.

The scientists combined existing physiological data on marine species with models of climate change in order to predict how environmental changes will affect the survival of sea animals over the next few centuries. 

The experts compared their models to past mass extinctions captured in the fossil record, such as the end-Permian extinction about 250 million years ago (the Earth’s deadliest extinction event, in which 81 percent of marine species was wiped out). This analysis revealed that, as in the case of previous extinctions, factors such as increased water temperatures and low oxygen availability will make large swaths of the ocean uninhabitable, leading to massive losses of marine life.

Although marine animals have physiological mechanisms flexible enough to allow them to cope with many environmental changes, the massive upheaval caused by unmitigated emissions would probably lead most polar species to extinction. While tropical marine animals may likely fare better because they have traits allowing them to adapt to warmer, low-oxygen conditions – and, in addition, they might have the possibility to migrate to newly suitable habitats – tropical biodiversity would nevertheless be severely affected. 

Fortunately, if urgent actions are taken to curb emissions, the risks of extinction and biodiversity loss could be reduced by 70 percent. “Aggressive and rapid reductions in greenhouse gas emissions are critical for avoiding a major mass extinction of ocean species,” said study senior author Curtis Deutsch, a professor of Geosciences at Princeton.

“The silver lining is that the future isn’t written in stone,” added study first author Justin Penn, a postdoctoral research associate working together with Professor Deutsch. “The extinction magnitude that we found depends strongly on how much carbon dioxide [CO₂] we emit moving forward. There’s still enough time to change the trajectory of CO₂ emissions and prevent the magnitude of warming that would cause this mass extinction,” he concluded.

The study is published in the journal Science.

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By Andrei Ionescu, Earth.com Staff Writer