Ocean Acidification is Occurring at Startling Rate of 5 Percent per Decade

Climate change isn't just heating things up. It's also causing the world's oceans to acidify. Now, a team of scientists has published the most comprehensive picture yet of how acidity levels vary across the world's oceans, revealing how humans impact their environment.

As the atmospheric levels of carbon dioxide have increased, so too have the levels in the ocean. In fact, the oceans have absorbed about a quarter of the carbon dioxide that humans have released into the atmosphere over the last 200 years. Yet while the oceans offset global warming because of this, they've also become more acidic due to the increased levels of CO2.

In order to better show how ocean acidity levels are rising, the scientists analyzed long-term data collected off Iceland, Bermuda, the Canary Islands, Hawaii and the Drake Passage, off the southern tip of South America. They found that waters as far north as Iceland as far south as Antarctica are acidifying at a rate of about 5 percent per decade. This corresponds with the amount of CO2 being added to the atmosphere.

"This is exactly what we'd expect based on how much CO2 we've been putting in the air," said Rik Wanninkhof, a NOAA researcher who was not involved in the study, in a news release. "This is an important point for scientists to underscore-these calculations are not magic."

If rates continue, then it's possible that by 2050, warm-water corals would be living in waters that are 25 percent more acidic than they are today. Corals currently can't tolerate shifts that are that big. However, it's possible that corals may be able to sustain the shift if it occurs gradually.

The researchers didn't just examine what was occurring, though. They also created maps of the process. The maps themselves use 2005 as a reference year and draw on four decades of measurements, and reveal details-such as that the northern Indian Ocean is at least 10 percent more acidic than the Atlantic and Pacific oceans.

The findings are published in the journal Marine Chemistry.