Thanks to climate change, “marine waters, even far out in the high seas, are losing oxygen … upending where and how sea creatures live,” says National Geographic, citing a study in the journal Science. “The authors conclude that it’s emptying vast regions of the ocean, changing what and where creatures live and eat, threatening to shrink fish populations and individual fish, and making overfishing more likely.”
The lead author of the study, Denise Breitburg, of the Smithsonian Research Center, likens the situation to destruction of an ecosystem. “If we were creating vast areas on land that were uninhabitable by most animals, we’d notice. But we don’t always see things like this when they are happening in the water.”
Low-oxygen zones occur naturally, but the zones have grown by more than 4.5 million square kilometers — roughly the same area as covered by EU nations — since the mid-20th Century,” said NatGeo. Warm water carries less oxygen than cold water and it boosts the metabolism of marine creature so they consume the oxygen more rapidly. Warm water is more buoyant than cold water, so the top layer of warm water makes it harder for oxygen to mix with colder water. “In fact, the world’s oceans have lost about two percent of their oxygen in just 50 years, while the amount of water that’s completely free of oxygen has increased fourfold, according to the new study.”