Global Warming Has Decreased Ocean Oxygen Levels – Nairobi Times

After the end of the UN Climate Change Conference (COP 26), in Scotland, on November 2, scientists are calling attention to yet another victim of climate change: the oxygen levels of the oceans. The increase in the frequency of so-called dead zones, where oxygenation is almost non-existent, will affect not only the diversity of marine life, but a large portion of the world’s population that depends on the sea to survive.

In an article published in Scientific American, Columbia University oceanographer Julie Pullen and American Museum of Natural History chemical oceanographer Nathalie Goodkin shed light on another disastrous but little-discussed consequence of climate change, namely the fall in oxygen levels in lakes and oceans around the world.

According to them, in the last North American summer, more than 160 km of the coastal waters of Florida became an extensive dead band, where countless fish floated without life, having been without oxygen. Meanwhile, on the other side of the country, crabs invaded the Oregon coast in an unsuccessful attempt to get out of oxygen-deprived water.

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A water without enough oxygen to support marine ecosystems will have consequences as disastrous as the accelerating increase in greenhouse gases (GHG) levels and ocean acidification — especially for the 3 billion people who live in coastal areas and live exclusively from fishing. Therefore, climate solutions must also be based on the oceans.

More heat, less oxygen

The scientists explain that as the concentration of atmospheric CO2 increases, it raises not just the temperature of the air, but of the water as well—the oceans absorb about 90 percent of the planet’s excess heat. While these waters can absorb both carbon dioxide and oxygen, they have a limit.

As water becomes hotter, the solubility of these gases decreases—that is, the more heat, the less oxygen dissolved in the water. But pollution from plastics and industrial waste runoff is already compromising marine ecosystems, stifling biodiversity — like the large-scale death of phytoplankton, they oxygenate the oceans.

The authors also report that large areas of the oceans have already lost between 10 to 40% of their oxygen, and this loss is likely to become more rapid as climate change intensifies. Despite efforts such as the UN’s Global Ocean Decade (2021-2030), very little is known about the relationship of the climate crisis with the oxygen in water.

urgent measures

Pullen and Goodkin propose improved monitoring of oxygen and the implementation of an accounting system for this gas — an initiative that could include benefits such as carbon sequestration by marine species such as algae and systems such as mangroves.

While COP26 showcased many initiatives and commitments to life on earth, they hope that the next climate conference, COP27, will encourage oceanic solutions based on nature itself — and that they will take effect as soon as possible.

If 40% of the world depends on the oceans to survive, putting oxygen in the climate crisis scenario is more than necessary for a real understanding of the consequences in the complex atmospheric and oceanic systems. “If we don’t prevent marine life from lack of oxygen, we will propagate yet another hoax on ourselves,” the authors conclude.