The world’s oceans are sick, and getting sicker every day.

This 2017 photo provided by NOAA shows bleached coral in Guam.

Two new studies show the warming of Earth’s atmosphere is removing oxygen from ocean waters and harming coral reefs.

Oxygen is necessary for all life in the oceans, except for a few extremely small organisms. And researchers said oxygen levels are low enough to threaten all the ocean life that depends on it.

Denise Breitburg is an ocean scientist at the Smithsonian Environmental Research Center. She is also a member of the Global Ocean Oxygen Network, a team of scientists organized by the United Nations to study the issue.

This May 2016 photo provided by NOAA shows bleaching and some dead coral around Jarvis Island, which is part of the U.S. Pacific Remote Marine National Monument.

Breitburg told the Associated Press, “If you can’t breathe, nothing else matters. That pretty much describes it.”

The journal Science published the two studies. The first describes how the growing problem of falling oxygen levels is more complex than experts had thought. The second study shows that rising ocean temperatures are greatly increasing coral reef bleaching events.

Scientists with the Global Ocean Oxygen Network reported that more than 32 million square kilometers of ocean are low in oxygen. These affected areas reach a depth of about 200 meters.

This area is bigger than Africa, the second largest continent. The scientists say the area of low oxygen levels has grown about 16 percent since 1950.

The Global Ocean Oxygen Network’s report is the widest reaching look at decreasing oxygen levels in the world’s seas so far. Lisa Levin is a professor at the Scripps Institution of Oceanography and a co-author of the report.

In her words, “The low oxygen problem is the biggest unknown climate change consequence out there.”

Levin said past research had shown low oxygen areas that were the result of agricultural pollution. She said past studies also showed how warmer waters had created a lack of oxygen. But Levin said this latest study shows how both problems are connected by common causes and possible solutions.

Co-author Denise Breitburg said that some low oxygen levels in the world’s ocean are natural, but not to the extent found. Wind patterns and ocean currents, believed changed by global warming, are preventing oxygen from sinking below the surface of the water. In addition, warmer water does not hold as much oxygen and less oxygen mixes into the water, she said.