A recent study from the journal Nature has found that, worldwide, the ocean’s oxygen content declined by more than 2% between 1960 and 2010. Though 2% doesn’t sound like a lot, it doesn’t take much to threaten the state of oceans.
The study, co-authored by Sunke Schmidtko, Lothar Stramma and Martin Visbeck, came from the GEOMAR Helmholtz Centre for Ocean Research in Kiel, Germany.

The study shows that the oxygen depletion in the ocean is due to climate change and in some parts of the world, the decline has been far worse; in the North Pacific, the largest volume of oxygen was lost and in the Arctic Ocean, the largest percentage was lost. And these losses have far-reaching impact, like on fisheries and coastal economies.
But another cause of oxygen depletion, also driven by climate change, is the ocean becoming more stratified (a result of changing temperature gradients in the Arctic, and the reduction of sea ice). From the article,
“Oxygen enters the water at the surface, but as that surface layer gets warmer, it’s less likely to sink to the oxygen-starved layers below. The study finds that the reduction of sea ice has led to more plankton growth — and with more plankton growth comes more plankton decomposition. Decomposition decreases oxygen levels even further.”
And in these areas when decomp has decreased oxygen levels you get a “dead zone,” a place where fish can’t thrive AND where the harmful greenhouse gas called nitrous oxide also exists in large quantities.
More from the article:
“Nitrous oxide is potent. It lasts in the atmosphere a long time and contributes to global warming — meaning that the effects of climate change on the world’s oceans causes more global warming, in turn.
…the world is edging closer to solving the carbon dioxide problem, it’s barely scratched the surface when it comes to the issue of nitrous oxide.”
Our only chance to stop this process in its tracks is to consume less and recycle more. While that’s possible it seems unlikely.
Our oceans are a mirror of human health and they are sick and dying. That should scare us.

Sources: CNN