Since 1960, the world’s oceans have lost more than 2 percent of oxygen that may lead to potential devastating consequences for sea plants and animals, marine scientists said.
Anoxic waters are part of the oceans with devoid of oxygen. Researchers found that in the past decades anoxic waters have quadrupled.
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The Earth's oceans provide half of the oxygen humans breathe, and provide food for billions of people. In a comment on the study that Nature
also published, research scientist Denis Gilbert of Fisheries and Oceans Canada wrote that a “two percent decrease of ocean oxygen content may not sound like much.”
However, he warned, “the implications of this for marine ecosystems could be severe in parts of the ocean where oxygen is already low.”
According to reports, the largest decrease was observed near areas where oxygen had been already low. Those parts of the world are called “dead zones,” where oxygen levels declined by 4 percent every decade.
Most oxygen was lost in the Equatorial and North Pacific Ocean, the Southern Ocean, and the South Atlantic Ocean.
The findings “should ring yet more alarm bells about the consequences of global warming,” Gilbert said.
According to Matthew Long, an oceanographer from the National Center for Atmospheric Research, “natural variations have obscured our ability to definitively detect this signal in observations. In this study, however, Schmidtko et al. synthesize all available observations to show a global-scale decline in oxygen that conforms to the patterns we expect from human-driven climate warming. They do not make a definitive attribution statement, but the data are consistent with and strongly suggestive of human-driven warming as a root cause of the oxygen decline.
“It is alarming to see this signal begin to emerge clearly in the observational data,” he said in an email.