What we can learn from an ocean extinction of 252 million years



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Kilauea lava in Hawaii flows into the ocean. I took this photo in October 2017. (Hawaii, United States) Marc Szeglat | Unsplash

Approximately 252 million years ago, when the continents were still merged like Pangea, our planet experienced a unparalleled loss of plant and animal life. While the mechanism for this & nbsp;"Great Permian Extinction"& nbsp; (where & nbsp;70% of terrestrial species died) & nbsp;has been largely unknown, & nbsp;a new study& nbsp; found that the disappearance of & nbsp;96% of marine life& nbsp;may have been due to hot oceans and low oxygen consumption. To reach this conclusion, the study innovatively combined the fossil record, experiments involving animal physiology, and state-of-the-art ocean models.

"Permian extinction was the perfect storm of catastrophic events, with carbon dioxide emissions and subsequent global warming accounting for 95 percent of all species on Earth," & nbsp; say Veronica Padilla Vriesman, a doctoral student in geology at the University of California, Davis, studying past changes in the ocean environment using archaeological shells. "The Earth has become a huge dead zone in a geologically short period of time. Recovery after extinction took millions of years, forever altering Earth's biota."

While oceanic and atmospheric conditions during Permian Period were similar to those of today, a series of intense volcanic eruptions in Siberia expelled large volumes of greenhouse gases in the atmosphere. Carbon dioxide levels were almost 12 times higher than those that are & nbsp;today, thus involving the Earth in a thick blanket that holds the heat. The authors determined that the Permian oceans heated by & nbsp; 20 & F; 11 & degrees;& nbsp; and lost up to 80% of the oxygen they contained (when the ocean temperature rises, they lose their ability to maintain oxygen). In addition, & nbsp;the waters closer to the seabed were completely devoid of oxygen.

To understand the impact of these stressful conditions on the animals that lived in the oceans at the end of the Permian Period, the authors referenced laboratory studies that tested the responses of 61 modern marine animals to changes in temperature and oxygen levels. They specifically selected animals that evolved under conditions similar to extinct species, such as corals, mollusks, and sharks.

The authors found that hot, low-oxygen water was the main source of extinction in the Permian oceans. With rising ocean temperatures, the metabolism of many marine creatures will have accelerated. However, deprived oceans of oxygen were probably unable to meet the physiological needs of Permian plants and animals by suffocating them, while carbon dioxide emissions from Siberia volcanoes may have dissolved in the sea water & nbsp;making the oceans more acidic& nbsp; and & nbsp;contributed to the loss of some species, warming and loss of oxygen are considered the main drivers of this massive death.

In addition, species in the tropics did not suffer as much as species found in colder waters near the poles. This is probably because the marine life closest to the equator has evolved to survive in warm and tropical waters.

"As the metabolisms of tropical organisms were already adapted to reasonably warm conditions and low oxygen, they could move away from the tropics and find the same conditions elsewhere, said co-author Dr. Curtis Deutsch& nbsp; "But if an organism were adapted to a cold, oxygen-rich environment, these conditions would cease to exist in shallow oceans."

In this photo of May 9, 2016, shellfish washed ashore covers the coast at Cucao, on the island of Chiloé, Chile. The government has declared an emergency zone along southern Chile and in Chiloé since it deals with the worst ever done in the country. "red tide," which can be lethal to fish and other marine forms with a toxin that paralyzes the central nervous system. The consumption of shellfish from red tide areas can also poison humans. (Photo AP / Esteban Felix)ASSOCIATED PRESSURE

This 252 million year-old ocean-going extinction event can provide some insight into the consequences of modern man-made changes in the climate and oceans of the Earth. & Nbsp;currently& nbsp; at the Anthropocene (the human age)the levels of carbon dioxide are higher than in 15 million years and the planet is the hottest in 120,000 years. In addition, & nbsp;if greenhouse gas emissions continue at their current rate, then ocean waters close to the surface could be 20% warmer than at the end of the Permian period until the year 2100 (and up to 50% as hot& nbsp; until the year 2300).

According to Padilla Vriesman, & nbsp; "We can see the advance of the final-Permian extinction as an analogue of what we are seeing on Earth today. Humans – rather than volcanoes – are provoking a global event with alarming characteristics similar to those leading to end of the Permian. "

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Kilauea lava in Hawaii flows into the ocean. I took this photo in October 2017. (Hawaii, United States) Marc Szeglat | Unsplash

Approximately 252 million years ago, when the continents were still merged like Pangea, our planet experienced a unparalleled loss of plant and animal life. While the mechanism for this "Great Permian Extinction" (where 70% of terrestrial species died) has been largely unknown, a new study has found that the disappearance of 96% of marine life may have been due to hot oceans and low oxygen consumption. To reach this conclusion, the study innovatively combined the fossil record, experiments involving animal physiology, and state-of-the-art ocean models.

"Permian extinction was the perfect storm of catastrophic events, with carbon dioxide emissions and subsequent global warming eliminating 95 percent of all species on Earth," says Veronica Padilla Vriesman, a Ph.D. student in geology at the University of California. in the ocean environment using archaeological shells. "The Earth has become a huge dead zone in a geologically short period of time. Recovery after extinction took millions of years, forever altering Earth's biota."

While oceanic and atmospheric conditions during the Permian period were similar to those of today, a series of intense volcanic eruptions in Siberia expelled large volumes of greenhouse gases into the atmosphere. Carbon dioxide levels were almost 12 times higher than today, thus involving the Earth in a thick blanket that holds the heat. The authors determined that Permian oceans warmed to 20 ° F (11 ° C) and lost up to 80% of the oxygen they contained (when ocean temperatures rose, they lost their ability to retain oxygen). Besides that, the waters closer to the seabed were completely devoid of oxygen.

To understand the impact of these stressful conditions on animals living in the oceans at the end of the Permian Period, the authors referenced laboratory studies that tested the responses of 61 modern marine animals to changes in temperature and oxygen levels. They specifically selected animals that evolved under conditions similar to extinct species, such as corals, mollusks, and sharks.

The authors found that warm, oxygen-poor waters were the main source of extinction in the Permian oceans. With rising ocean temperatures, the metabolism of many sea creatures will have accelerated. However, the oceans deprived of oxygen were probably unable to meet the physiological needs of Permian plants and animals, eventually choking them. While carbon dioxide emissions from Siberian volcanoes may have dissolved in seawater, making the oceans more acidic and contributing to the loss of some species, heating and loss of oxygen are considered to be the most responsible By this extinction.

In addition, species in the tropics did not suffer as much as species found in colder waters near the poles. This is probably because the marine life closest to the equator has evolved to survive in warm and tropical waters.

"As the metabolisms of tropical organisms were already adapted to reasonably warm conditions and low oxygen, they could move away from the tropics and find the same conditions elsewhere, "said co-author Dr. Curtis Deutsch. But if an organism has been adapted to a cold, oxygen-rich environment, then these conditions cease to exist in shallow oceans. "

In this photo of May 9, 2016, shellfish washed ashore covers the coast at Cucao, on the island of Chiloé, Chile. The government has declared an emergency zone along southern Chile and Chiloé as it deals with the country's worst "red tide," which can be lethal to fish and other marine forms with a toxin that paralyzes the central nervous system . The consumption of shellfish from red tide areas can also poison humans. (Photo AP / Esteban Felix)ASSOCIATED PRESSURE

This ocean extinction event that occurred 252 million years ago can provide some insight into the consequences of modern man-made changes in the climate and oceans of the Earth. Currently in the Anthropocene (the human age), carbon dioxide levels are higher than in 15 million years and the planet is the hottest in 120,000 years. In addition, if greenhouse gas emissions continue at their current rate, then ocean waters close to the surface could be 20% warmer than at the end of the Permian by 2100 (and up to 50% by the year 2300). ).

According to Padilla Vriesman, "We can look at the extinction of the end of the Permian as an analogue to what we are seeing on Earth today. Humans – rather than volcanoes – are provoking a global event with alarming characteristics similar to those leading to the end -Permiano ".

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