The weather is getting hotter and sea changes are already happening. Earth’s oceans are warmer than they were a century ago, sea levels are rising, and ocean waters are more acidic than they used to be, all because of human-created climate change.
Earth has endured at least five global extinction events since the first signs of life appeared. And researchers believe that it may be teetering on the edge of another one in the oceans.
If climate change continues unabated, marine life worldwide could suffer a mass die-off, the likes of which hasn’t been seen in hundreds of millions of years.
In the latest study in the journal Science by Princeton researchers Justin Penn and Curtis Deutsch, their research warns that failing to reduce fossil fuel emissions will set Earth’s oceans on track for a mass extinction within the next 300 years. Yet the study also underscores how much marine life could still be saved. If the world takes swift action to curb fossil fuel use and restore degraded ecosystems, the scientists say, it could cut potential extinctions by 70 percent.
Using climate models that predict the behavior of species based on simulated organism types, Deutsch and Penn found that the number of local disappearances of particular species, increases about 10 percent with every 1 degree Celsius of warming.
The scientists tested their models by using them to simulate a mass extinction at the end of the Permian-era, when catastrophic warming triggered by volcanic eruptions wiped out roughly 90 percent of all life on Earth. Because the models successfully replicated the events of 250 million years ago, the scientists were confident in their predictions for what might happen 300 years in the future.
Penn and Deutsch’s research revealed that most animals can’t afford to lose much more than 50 percent of their habitat and beyond that number, a species tips into irreversible decline. In the worst-case emissions scenarios, the losses would be on par with the five worst mass extinctions in Earth’s history. They also demonstrate that keeping those temperatures in check can dramatically reduce the risk of both local and global extinctions.
Looking centuries into the future, the study emphasizes that now is the time to forestall some of these possible consequences for our oceans. The global climate is expected to get about 3.6 degrees Fahrenheit warmer by 2100. If emissions can be curbed and warming kept around this minimum, then these mass extinction scenarios can be avoided.
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SCIENCE: “Temperature-dependent hypoxia explains biogeography and severity of end-Permian marine mass extinction.”
SCIENTIFIC AMERICAN: “Scientists Warn of Looming Mass Ocean Extinction.”
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