New Scientist summarizes the recent State of the Oceans Report.
“We know the oceans are warming. We know they are acidifying. And now, to cap it all, it turns out they are suffocating, too. A new health check on the state of the oceans warns that they will have lost as much as 7 per cent of their oxygen by the end of the century.
The health of the oceans is spiralling downwards far more rapidly than we had thought, exposing organisms to intolerable and unpredictable evolutionary pressure…
(There is) a “deadly trio” of linked global threats. The first is global warming: surface sea water has been warming almost as fast as the atmosphere. The second is acidification – a result of the water absorbing ever more CO2 from the atmosphere. The third is deoxygenation…..
… acidification is beginning to affect marine creatures (but) …. low oxygen has a greater effect than acidification”.
The oceans are losing oxygen partly because warmer water holds less oxygen, and partly because warming is greatest at the surface, creating a buoyant surface layer that mixes less with colder layers below. This creates oxygen-poor deep water that could suffocate life on the seabed….
The complete SOTO report is here.