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Ecological cataclysm is approaching, alert researchers

By Vincent Deroy

Decreasing the amount of oxygen could become a huge problem for the oceans, warn researchers who have analyzed periods of climate change in the past.

A major study by researchers at the University of Otago (New Zealand) has highlighted a new dangerous factor in global warming: the depletion of oxygen, reports Phys.org.

The study, which has just been published in the journal Proceedings of the National Academy of Sciences (PNAS), examined a period of global warming that occurred about 94 million years ago, when the oceans were deoxygenated.

The researchers applied a revolutionary new tool to examine how the oceans have responded to climate change in the past. The model they developed allowed the team to calculate the quantities of carbon injected into the atmosphere to trigger each of the two phases of the oceanic anoxic event (episode of large-scale reduction of oxygen concentration on a very large scale). in the oceans, recurrently recorded in sediments during the geological history of the Earth).

Scientists have used a new technique, which measures the natural uranium isotopes of ancient sediments, which could be used to estimate the oxygen content of the oceans. They applied this technique to geological sediments that were once deposited in the ocean and are now preserved on the white cliffs of southern England, as well as in Italy.

They discovered that this anoxic event, or deoxygenation, was due to high CO2 emissions and higher temperatures; and when CO2 emissions went down, the world's oceans were recovering for a while.

Areas of deoxygenation of the oceans, known as "dead zones", are currently found in several oceans, especially in the eastern parts of the Pacific, Atlantic and Indian oceans. "Dead zones" occur because oxygen is difficult to dissolve in water when the oceans are hot, and decomposition of biological material requires more oxygen. In these areas, there are large amounts of nutrients, which creates large amounts of organic matter, and therefore more oxygen is used.

The number of these "dead zones" would be more than 400 in recent years, according to researchers.

Sources: Wikistrike , SputnikNews , March 9, 2018