Global Maps Detail Seasonal and Geographic Trends in Ocean Acidification

A team of scientists has published the most comprehensive analysis yet of how acidity levels vary across the world’s oceans. Drawing on four decades of

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Taro Takahashi
Ocean acidification map
measurements, researchers from Columbia University and the University of Colorado mapped changes in ocean acidity by season and location, as well as how acidity levels affect the stability of shell-building minerals. The maps reveal that the northern Indian Ocean is at least 10 percent more acidic than the Atlantic and Pacific oceans, possibly due to its unique geography, the researchers say. The maps also show that ocean acidity fluctuates most in the colder waters off Siberia, Alaska, Antarctica, and the Pacific Northwest, due to cycles of deep-water upwelling and massive plankton blooms. The oceans have taken up a quarter of the carbon dioxide humans have put in the atmosphere over the last two hundred years, and acid levels at the surface have increased by 30 percent since the beginning of the industrial era, researchers say.