We know more about the Moon than we know about the oceans on Earth, and as more research pours out of the depths, new findings are being unravelled. A new study reveals how oxygen boosted life in the waters of Earth’s oceans and then suddenly disappeared.
Researchers have looked at the continental movement to understand the circulation of life-supporting oxygen in the oceans and how it could have the opposite effect, killing most deep ocean creatures. The study revealed that the circulation of oxygen and nutrients can end quite suddenly.
The findings of the study published in the journal Nature state that the early evolutionary and much of the extinction history of marine animals is thought to be driven by changes in dissolved oxygen concentrations in the ocean and is widely assumed to be dominated by the geological history of atmospheric oxygen.
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“Continental drift seems so slow, like nothing drastic could come from it, but when the ocean is primed, even a seemingly tiny event could trigger the widespread death of marine life,” Andy Ridgwell, UC Riverside geologist and co-author of the study released said in a statement.
Fish swimming through the coral on Australia’s Great Barrier Reef. (Photo: AFP)
THE GAME OF OXYGEN
While life flourishes across oceans, in frigid world of the poles, it is triggered when oxygen pulled from Earth’s atmosphere reaches down to the ocean floor. The oxygen is transported to the bottom as it sinks as water becomes colder and denser at the poles. A return flow then brings the organic matter back to the ocean’s surface, which leads to the growth of plankton.
Researchers developed complex computer models to investigate whether the locations of continental plates affect how the ocean moves oxygen around. They found that the global ocean circulation seemed to periodically shut down. They call it ocean anoxia — times when oceanic oxygen disappeared.
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“Many millions of years ago, not so long after animal life in the ocean got started, the entire global ocean circulation seemed to periodically shut down. We were not expecting to find that the movement of continents could cause surface waters and oxygen to stop sinking, and possibly dramatically affect the way life evolved on Earth,” Ridgwell added.
The early evolutionary and much of the extinction history of marine animals is thought to be driven by changes in dissolved oxygen. (Photo: AFP)
The study revealed that collapse in global water circulation led to a stark separation between oxygen levels in the upper and lower depths. This loss spanned through the entire seafloor, except, places close to the coast, and the shutdown remained in place until 440 million years ago.
CAN IT HAPPEN AGAIN?
While researchers are still looking to understand if it could happen, they are trying to find out when can it happen. They said that while it is difficult to identify when a collapse might occur, or what triggers it, ” existing climate models confirm that increasing global warming will weaken ocean circulation.”
“We’d need a higher resolution climate model to predict a mass extinction event. That said, we do already have concerns about water circulation in the North Atlantic today, and there is evidence that the flow of water to depth is declining,” Ridgwell said adding that d an unusually warm summer or the erosion of a cliff could trigger a cascade of processes that upends life as it appears today.
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