Oceans acidifying 10 times faster than thought

Scientists are already measuring declines in populations of creatures as a result of acidification—and notably the replacement of certain shellfish by acid-tolerant seaweeds.Ocean acidification is perhaps the most under-reported feature of the steady advance of the amount of carbon dioxide in the atmosphere.“For a potential environmental problem that is receiving increasing attention, there is surprisingly little published data in the scientific literature on how pH in the ocean is actually changing over time.

And none that we know of outside of the tropics,” said Tim Wootton, of the Department of Ecology and Evolution at the University of Chicago.Some of the seminal research on sea acidification was performed in Hawaiian waters just within the past couple of years. But new research is adding breadth and depth to that data—and it is finding that the oceans are growing acid alarmingly faster than anyone thought.

Wootton's team, including colleagues Catherine Pfister and James Forester, conducted a multi-year study of ocean acidity off Washington State. One of their findings was that there is considerable variability in the pH level of the ocean, based largely in changes in ocean biology. But the other finding was that acidity is rising very fast.Their paper, “Dynamic patterns and ecological impacts of declining ocean pH in a high-resolution multi-year dataset,” was published in the Proceedings of the National Academy of Sciences.

The fundamental process is this: As carbon dioxide increases in the air, it mixes with the water, forming carbonic acid. The result is that the pH of the ocean—the measure of water acidity or alkalinity—is decreasing. That means the ocean is growing more acid.“An alarming surprise is how rapidly pH has declined over the study period at our site--about 10 times faster than expected,” Wootton said in an email to RaisingIslands.