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).
Alice Friedemann www.energyskeptic.com author of “When Trucks Stop Running: Energy and the Future of Transportation”, 2015, Springer, Barriers to Making Algal Biofuels, and “Crunch! Whole Grain Artisan Chips and Crackers”. Podcasts: Collapse Chronicles, Derrick Jensen, Practical Prepping, KunstlerCast 253, KunstlerCast278, Peak Prosperity , XX2 report
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.