Ocean Warning

They call it “The Blob.” A vast expanse of ocean stretching from Alaska to California periodically warms by up to 4 degrees Celsius (7 degrees F), decimating fish stocks, starving seabirds, creating blooms of toxic algae, preventing salmon returns to rivers, displacing sea lions, and forcing whales into shipping lanes to find food. The Blob first formed in 2013 and spread across an area of the northeast Pacific the size of Canada. It lasted for three years and keeps coming back — most recently last summer. Until now, scientists have been unable to explain this abrupt ocean heating. Climate change, even combined with natural cycles such as El Niño, is not enough. But new analysis suggests an unexpected cause. Xiaotong Zheng, a meteorologist at the Ocean University of China, and international colleagues argue that this extraordinary heating is the result of a dramatic cleanup of Chinese air pollution. The decline in s...