The world’s oceans may be acidifying more rapidly than they have at any time in the past 300 million years due to high levels of pollution, according to research published this week in the journal Science.
Researchers, led by Columbia University’s Lamont-Doherty Earth Observatory and the University of Bristol, assessed a number of climate change events in Earth’s history, including an asteroid impact that wiped out the dinosaurs 65 million years ago.
They warn that too much carbon dioxide in the atmosphere is the key factor that will make the oceans more acidic and imperil key parts of the marine food chain. It has happened before, and can happen again, they warn. In fact, ocean acidification appears to be occurring now at an unprecedented pace.
The study is the first of its kind to survey the geologic record for evidence of ocean acidification over such a large time period.
“What we’re doing today really stands out in the geologic record,” said study leader Bärbel Hönisch, a paleoceanographer at Columbia University. “We know that life during past ocean acidification events was not wiped out — new species evolved to replace those that died off. But if industrial carbon emissions continue at the current pace, we may lose organisms we care about — coral reefs, oysters, salmon.”
The world’s oceans act like a sponge, drawing excess carbon dioxide from the air, soaking it up. The gas reacts with seawater to form carbonic acid, which over time is neutralized by fossil carbonate shells on the seafloor.
If too much carbon dioxide enters the ocean too quickly, it can deplete the carbonate ions that corals, mollusks and plankton need for reef and shell-building.
In their review of hundreds of paleoceanographic studies, the team of researchers found evidence for only one period of time in the last 300 million years when the oceans changed as fast as they are today: the Paleocene-Eocene Thermal Maximum, or PETM.