Ocean oxygen levels lower than previously estimated, study reports

Scientists have found that global warming is rapidly robbing the oceans of oxygen.
By Joseph Scalise | Jan 06, 2018
Global warming is harming the world's oceans in a variety of ways, and new research from a team of international scientists shows rapidly depleting oxygen levels are one of the biggest.

Low oxygen levels are massive problems for marine ecosystems because, not only do they harm delicate coral reefs, but they also make marine life much more vulnerable to environmental problems. Just about every single underwater organism -- with the exception of a few microbes -- needs oxygen to live and will quickly die without it.

"If you can't breathe, nothing else matters. That pretty much describes it," said lead author Denise Breitburg, a marine ecologist at the Smithsonian Environmental Research Center, according to ABC News. "As seas are losing oxygen, those areas are no longer habitable by many organisms."

In the study, the researchers found that there are more than 12 million square miles with low oxygen levels at a depth of several hundred feet. That is an area bigger than both Africa or North America, and it amounts to an oxygen depletion increase of roughly 16 percent since 1950.

Past research has revealed a series of coastal "dead zones" created by fertilizer pollution, as well as areas of low oxygen in open ocean. However, this study is unique because it shows how those two problems are linked to common causes.

While some low oxygen levels are natural, the amount found in the study goes far beyond that amount. Wind and current changes leave oxygen on the surface, which then depletes deeper areas. In addition, warm water holds less oxygen than cold water. As seas continue to warm, less and less oxygen is being trapped and taken below the surface.

This research reveals that oxygen depletion is a growing problem that is much larger than previously thought. Scientists have been aware of the issue for years, but they did not know the extent until now.

Even so, while the news is concerning, there are certain steps that can be taken in order to help prevent further damage. The team in the study suggests that steps need to be taken to protect vulnerable marine life, especially at-risk fisheries and coral reefs. Further monitoring could also be useful in pinpointing which places are most at risk and figuring out the most effective solutions.

"This is a problem we can solve," added Breitburg, according to Phys.org. "Halting climate change requires a global effort, but even local actions can help with nutrient-driven oxygen decline."

The new research is outlined in the journal Science.

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