Oceans start dangerously lacking oxygen

Oceans start dangerously lacking oxygen


A report from IUCN suggests that the oceans have lost a lot of oxygen since the 1960s. In addition, there are now fifteen times more “dead zones” than sixty years ago.

Terrestrial species need oxygen to live, but let’s not forget that marine species also. You and I do not run out of oxygen. In contrast, fish and shellfish begin to suffocate. In any case, this is the result of a new report signed by IUCN.

We learn that the oceans around the world have lost about 2% of their oxygen between 1960 and 2010. There are also 700 “dead zones” (parts of the ocean where oxygen is absent) against 45 counted there about sixty years ago.

Man largely responsible
This phenomenon of deoxygenation occurs because oxygen is less soluble in warmer water. It has always existed, which can be caused naturally by extreme weather events or particular ocean currents, for example. On the other hand, human activities tend to warm the oceans more since the beginning of the industrial era. The phenomenon of deoxygenation is then exacerbated.

The problem is that many species like tuna or sharks are sensitive to these oxygen levels. These fish can indeed be very big and spend a lot of energy. Crustaceans are also in the front line as they can not escape these “dead zones”. As a result, they die on the spot, usually following the development of methanogenic bacteria.

Immediate measures
The report is already worrying, but the researchers point out that the problems will only get worse if nothing is done to stem the climate crisis. At the current rate, oxygen levels in the ocean could drop by up to 4% by 2100. If this is the case, then the food chain will be dangerously under pressure.

“Oxygen depletion of the oceans threatens marine ecosystems that are already under stress from global warming and ocean acidification,” says Dan Laffoley, co-author of this report. “To stop the worrying expansion of oxygen-poor areas, we must decisively reduce greenhouse gas emissions and nutrient pollution from agriculture and other sources.”

Minna Epps, Director of IUCN’s Global Marine and Polar Program, turns to politics, while the COP25 is taking place in Madrid. “Urgent global action to overcome and reverse the effects of ocean deoxygenation is needed,” she said. “If nothing is done, marine areas once rich in oxygen will be irrevocably lost.”