Seas becoming more corrosive.

• Position: The Arctic

Surface waters of the Chukchi and Beaufort seas could reach levels of acidity that threaten the ability of animals to build and maintain their shells by 2030, with the Bering Sea reaching this level of acidity by 2044, according to research by the National Oceanic and Atmospheric Administration; Woods Hole (Mass.) Oceanographic Institution; and the University of Alaska, Fairbanks.

"Our research shows that, within 15 years, the chemistry of these waters may no longer be saturated with enough calcium carbonate for a number of animals from tiny sea snails to Alaska King crabs to construct and maintain their shells at certain times of the year," says lead author Jeremy Mathis, oceanographer at NOAA's Pacific Marine Environmental Laboratory, Seattle, Wash. 'This change due to ocean acidification would not only affect shell-building animals, but could ripple through the marine ecosystem."

A team of scientists led by Mathis and UA's Jessica Cross collected observations on water temperature, salinity, and dissolved carbon during expeditions to the Bering, Chukchi, and Beaufort seas. The data was used to validate a predictive model for the region that calculates the change over time in the amount of calcium and carbonate ions dissolved in seawater, an...