World’s Oceans are losing Oxygen rapidly

Preface. Yikes, add deoxygenization to your list of worries. Oxygen levels in the world’s oceans declined by roughly 2% from 1960 and 2010. The decline was largely due to climate change, though other human activities such as nutrient runoff from farms into waterways added to the problem.

That’s a deadly big deal. An increase in the water temperature of the world’s oceans of around six degrees Celsius — which some scientists predict could occur as soon as 2100 — could stop oxygen production by phytoplankton by disrupting the process of photosynthesis. About two-thirds of the planet’s total atmospheric oxygen is produced by ocean phytoplankton. Cessation would result in the depletion of atmospheric oxygen on a global scale resulting in a mass die-off of humans and other creatures (Sekerci 2015).

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Pierre-Louis, K. 2019. World’s Oceans are losing Oxygen rapidly, study finds. New York Times.

The world’s oceans are gasping for breath, a report issued Saturday at the annual global climate talks in Madrid has concluded.

The report represents the combined efforts of 67 scientists from 17 countries and was released by the International Union for Conservation of Nature. It found that oxygen levels in the world’s oceans declined by roughly 2 percent between 1960 and 2010. The decline, called deoxygenation, is largely attributed to climate change, although other human activities are contributing to the problem. One example is so-called nutrient runoff, when too many nutrients from fertilizers used on farms and lawns wash into waterways.

Water holds less oxygen by volume than air does. And as ocean temperatures increase, the warmer water can’t hold as much gas, including oxygen, as cooler water.  Warming temperatures also affect the ability of ocean water to mix, so that the oxygen absorbed on the top layer doesn’t properly get down into the deeper ocean. And what oxygen is available gets used up more quickly because marine life uses more oxygen when temperatures are warmer.

The decline might not seem significant because, “we’re sort of sitting surrounded by plenty of oxygen and we don’t think small losses of oxygen affect us,” said Dan Laffoley, the principal adviser in the conservation union’s global marine and polar program and an editor of the report. “But if we were to try and go up Mount Everest without oxygen, there would come a point where a 2 percent loss of oxygen in our surroundings would become very significant.”

“The ocean is not uniformly populated with oxygen,” he added. One study in the journal Science, for example, found that water in some parts of the tropics had experienced a 40 to 50 percent reduction in oxygen.

We see this along the coast of California with these mass fish die-offs as the most dramatic example of this kind of creep of deoxygenation on the coastal ocean.

According to Dr. Laffoley, if the heat absorbed by the oceans since 1955 had gone into the lower levels of the atmosphere instead, land temperatures would be warmer by 65 degrees Fahrenheit, or 36 degrees Celsius.


Sekerci, Y., et al. 2015. Mathematical Modelling of Plankton–Oxygen Dynamics Under the Climate Change. Bulletin of Mathematical Biology.

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7 Responses to World’s Oceans are losing Oxygen rapidly

  1. Rod says:

    Sheesh, must we blame everything on climate change? How about we humans stop treating our oceans like a garbage dump. We are like the little kid who’s mom says to cleanup their room and we throw all of our toys under the bed. Viola, clean room.

    That’s exactly what we are doing to our oceans !

    SkyNews UK, did a report a couple of years ago about micro-plastics that are now in our oceans at an alarming rate. We are now consuming those micro-plastics, the fish are eating.

    It’s been known for decades that NYC was dumping its garbage miles off their Coast into the oceans. When the Malaysian Airliner mysteriously went down and rescue teams went looking for it, they found debris in Australian waters. Upon closer inspection, it wasn’t airplane debris “IT WAS GARBAGE”. We have created ocean “dead zones” because of the crap we dump in our oceans.

    We grown up humans are like little Tommy who’s been told to cleanup his room. We dump toxic chemicals, pesticides, paints, plastics, garbage, and even nuclear waste. Tepco is considering dumping its radioactive wastewater from the Fukushima accident into the Pacific Ocean.

    Climate change is the least of our problems that we have created in our polluted oceans if we continue to treat them as a sight unseen garbage dump. So let’s be a little more responsible and careful about not using our oceans as an underwater “Landfill” before we play the Climate Change” card.

    • David Higham says:

      The oceans have multiple ecosystem stressors occurring simultaneously. You might like to ignore the effects of planetary
      heating on the oceans,but they are occurring,just as pollution,overfishing,changes to ocean chemistry,and destruction of ocean floor ecosystems by
      ocean floor trawling are occurring.

      • Rod says:

        And I feel you are also ignoring the levels of toxic pollution we are directly dumping into our oceans which is killing not only our oceans but that which resides in it.

        This is why the Climate Change movement gets dismissed by the general mainstream public because there is a problem that we can address, NOW (quit using the oceans as a garbage dump) but we decide to blame it on something else (climate change).

  2. Nehemiah says:

    In my experience, NYT is not a reliable source of science news, especially on political “hot button” topics such as climate change. And the link at the bottom to a real science journal is a 2015 paper on “mathematical modeling,” not empirical measurements. The story also acknowledges that oxygen levels in the ocean are far from uniform, which makes the question very difficult to investigate. I would rate this story somewhere between overtly bogus and very shaky. I still remember the NYT’s story on disappearing polar bears at a time when the polar bear population had tripled in size. An avalanche of unusually shoddy science papers and sensational predictions (all failures) since the 1990’s has made me increasingly skeptical of science stories dealing with fashionable topics. The best science gets done in fields that activists pay no attention to–in fact, because they are paying no attention to them.

  3. Nehemiah says:

    From the NYT story: “According to Dr. Laffoley, if the heat absorbed by the oceans since 1955 had gone into the lower levels of the atmosphere instead, land temperatures would be warmer by 65 degrees Fahrenheit, or 36 degrees Celsius.” — I am willing to wager my total life’s savings that this ridiculous claim is wrong. It doesn’t even pass the sniff test. It is either totally false or grossly misleading, something he can get away with telling scientifically illiterate journalists but would be laughed at if he tried to pass it off as a serious finding in a peer reviewed science journal.

    • Ken Barrows says:

      Why doesn’t it pass “the sniff test?” For example, it takes a lot of energy to change ice to water. Apply the same energy to the liquid state and temperatures rise rapidly. Not everything is linear.

      Good job of being provocative, but include a link or some reasoning once in a while.

  4. Ozquoll says:

    My response to Dr Laffoley’s claim is not “That’s wrong”, but “So what?”. Our planet is two-thirds covered by water, so of course most of the increased heat has been absorbed by the oceans. It is entirely irrelevant to our predicament to know how much our atmosphere would have heated up if we didn’t have oceans.