Oceans suffocating as huge dead zones quadruple since 1950, scientists warn

Saturday, 06 Jan, 2018

Scientists expect oxygen to continue dropping even outside these zones as Earth warms.

Denise Breitburg, at the Smithsonian Environmental Research Center in the United States and who lead the analysis, explained the grim situation that Earth is facing.

Human activities are largely responsible for the growth of ocean dead zones. "Unfortunately, it will take severe and persistent mortality of fisheries for the seriousness of low oxygen to be realized", Robert Diaz, a professor at the Virginia institute of Marine Science who reviewed the study, told the Guardian.

"It is enormous. We are already losing cod in deep waters, "said Gilbert".

The latest findings are alarming because almost half of the oxygen on Earth comes from the ocean.

Lucia von Reusner, campaign director of campaign group Mighty Earth, which recently exposed a link between the dead zone in the Gulf of Mexico and large scale meat production, said: "These findings are no surprise, and further confirm that the unchecked pollution from industrial agriculture has reached crisis levels and requires immediate action". While some animals can thrive in dead zones, overall biodiversity falls. But at sea, it is certainly climate change that is the main culprit, by far. Since warm water is lighter than cold water, less-oxygenated water also tends to displace oxygen-rich cold waters, making it harder for gases from the atmosphere to mix in. Gradually, the oxygen they hold gets used up by bacteria. As the microorganisms die and decompose, they rob the water of oxygen, creating massive dead zones.

Dead corals and crab shells

Although oceans are bleeding more oxygen than ever, researchers say if humans try to slow climate change and pollution, we could help oceans get back to producing more oxygen. In the Philippines, fish kills in a single town's aquaculture pens cost more than $10 million. Coral reefs, a key tourism attraction in many countries, also can waste away without enough oxygen.

Some popular fisheries could benefit, at least in the short term. While neither issue is simple or easy, the steps needed to win can benefit people as well as the environment. We need better septic systems to protect humans as well as keep nutrients and pollution out of the water. Cutting fossil fuel emissions can also slash air pollution.

Climate and oxygen levels have an interesting correlation. In these waters where they have to breathe more, there is less oxygen, "said the researcher". Enhanced monitoring, especially in developing countries, and numerical models will help pinpoint which places are most at risk and determine the most effective solutions.

"This is a problem we can solve", Breitburg said. Researchers believe that the world needs to rein in both climate change and nutrient pollution in order to halt the decline. While some low-oxygen zones persist, the area of the Chesapeake with zero oxygen has nearly disappeared. While low ocean oxygen levels may seem to be low on the list of climate change priorities, the authors raise the possibility of this having a perhaps unwanted positive feedback loop.

Recent research reveals these dead zones could become much more common throughout the world's oceans. Its ecologists do research from the center's Chesapeake Bay headquarters in Edgewater, Md., and in coasts around the world. Scientists suspect that oxygen will drop even in other parts of the oceans as global temperatures begin to climb.