The Chesapeake Bay has struggled for decades with dead zones — areas in which the water contains little or no oxygen, which sometimes causes massive fish kills. But while the problem has eased here in recent years, it has developed and worsened elsewhere around the globe, researchers say.
Since 1950, the number of coastal ecosystems that scientists say are “suffocating” has grown tenfold. The problem has grown four times over in the open ocean, which is generally a more stable and resilient environment.
Scientists say ocean oxygen content has declined 2 percent over the past 50 years.
Scientists say the trend is another consequence of global warming that threatens to...