Topline
Climate change could set up the Earth’s oceans for one of the worst mass extinction events in the planet’s history over the next 300 years, a new study published Thursday estimates, but the risk to marine life will plummet if greenhouse gas emissions are controlled.
Key Facts
The study by researchers at Princeton University—published in the journal Science—used a model to estimate how various levels of Earth-warming greenhouse gas emissions would cause marine animals to lose their habitats and go extinct.
Under a high-emission scenario that causes global air temperatures to jump by 4.9 degrees Celsius over the next century and keep rising thereafter, around 30% of ocean-dwelling animals may go extinct by the year 2300, an event that would “rival the severity of past mass extinctions” over hundreds of millions of years.
These extinctions would be triggered by a increase in the ocean’s temperature, which threatens marine animals across the globe by both taking away their usual habitats and causing water to hold less oxygen.
However, under a low-emission scenario that causes air temperature increases to stop at 1.9 degrees Celsius by 2100, the severity of any marine animal extinctions would shrink by 70%, the study found.
Crucial Quote
“The silver lining is that the future isn’t written in stone,” Justin Penn, a Princeton postdoctoral researcher who wrote the study alongside geosciences professor Curtis Deutsch, said in an article published by Princeton. “There’s still enough time to change the trajectory of CO2 emissions and prevent the magnitude of warming that would cause this mass extinction.”
Key Background
As emissions of greenhouse gasses like carbon dioxide trigger worldwide temperature increases, experts have long warned this trend could pose dire risks to marine- and land-based life. Under the 2015 Paris Agreement, hundreds of countries agreed to prevent global warming from exceeding 1.5 to 2 degrees Celsius above pre-industrial levels—which corresponds to the low-emission scenario in Tuesday’s study—but meeting this goal could prove difficult. A February report by the Intergovernmental Panel on Climate Change warned temperatures could climb by 1.5 degrees Celsius within the next two decades, likely causing severe weather and large-scale extinctions, and the window to prevent further damage by slashing emissions is “brief and rapidly closing.”
Surprising Fact
The risk of extinction isn’t spread evenly throughout the Earth’s oceans, the study estimated. Marine animals near the north and south poles face the greatest risk of peril because the cold-water habitats they rely on could gradually disappear altogether, whereas tropical species may survive by migrating north and south as temperatures increase.
Tangent
Even without factoring in climate change, human-caused phenomena like overfishing and pollution have put pressure on marine life. But Thursday’s study estimates if greenhouse gas emissions remain high, the impact of climate change on marine animals could eclipse the negative impacts of all other man-made threats to the world’s oceans by 2100.
