Entire Areas Of The Ocean Have Been Depleted Of Oxygen

World map: Dead zones, zones in alarming condition, recovering areas and natural O2 minimum zones Graph: Ocean Atlas 2017, Petra Böckmann/Heinrich Böll FoundationCC BY-SA 2.0

Ocean dead zones, depleted of oxygen, have quadrupled in size since 1950, scientists say.

Human induced climate change has led to warmer ocean temperatures, resulting in a quadrupling of oxygen-depleted ocean dead zones since 1950, according to scientists.

Most sea creatures cannot survive in these zones and current trends would lead to mass extinction in the long run, risking dire consequences for the hundreds of millions of people who depend on the sea.

Climate change caused by fossil fuel burning is the cause of the large-scale deoxygenation, as warmer waters hold less oxygen. The coastal dead zones result from fertiliser and sewage running off the land and into the seas.

Denise Breitburg, of the Smithsonian Environmental Research Center, believes this is a problem that can still be solved:

“Halting climate change requires a global effort, but even local actions can help with nutrient-driven oxygen decline.” She pointed to recoveries in Chesapeake Bay in the US and the Thames river in the UK, where better farm and sewage practices led to dead zones disappearing.

For those disinclined toward compassion for sea creatures, it is imperative to note that the oceans supply untold numbers of humans with food and work.

The oceans feed more than 500 million people, especially in poorer nations, and provide jobs for 350 million people. But at least 500 dead zones have now been reported near coasts, up from fewer than 50 in 1950. Lack of monitoring in many regions means the true number may be much higher.

Prof Robert Diaz at the Virginia Institute of Marine Science is concerned that governments are not giving the issue high enough priority, saying "it will take severe and persistent mortality of fisheries for the seriousness of low oxygen to be realised.”

Diaz said the speed of ocean suffocation already seen was breathtaking: “No other variable of such ecological importance to coastal ecosystems has changed so drastically in such a short period of time from human activities as dissolved oxygen.”

He said the need for urgent action is best summarised by the motto of the American Lung Association: “If you can’t breathe, nothing else matters.”