Ancient volcanoes once promoted ocean carbon, but humans are now removing them

A living foraminifera, a type of marine plankton, developed by researchers in laboratory culture. To reconstruct past climate, fossil specimens are collected from deep-sea sediment. Sincerely: Bärbel Hönisch / Lamont-Doherty Earth Observatory

A new study of an ancient period considered to be the closest natural analogue to the era of modern human carbon emissions has found that large-scale volcanoes sent great waves of carbon into the oceans over thousands of years — but that did not come close to matching nature Was what humans are doing today. Studies estimate that humans are now introducing the element three to eight times faster, or possibly even more. The consequences of life on both water and land are potentially disastrous. The findings appear in the journal this week Proceedings of the National Academy of Science.

Researchers at Columbia University’s Lamont-Doherty Earth Observatory investigated the state of the ocean 55.6 million years ago, once known as the Paleocene – Eocene Thermal Maxim (PETM). Earlier, the planet was already much warmer than today, and rising CO2 Paytm levels raised the temperature by another 5 to 8 ° C (9 to 14 ° F). The oceans absorbed large amounts of carbon, sparking chemical reactions that made the water extremely acidic, and killed or degraded other marine species.

Scientists have known about Paytm carbon growth for years, but until now, it has been unstable for what reason. In addition to volcanoes, hypotheses include the sudden dissolution of frozen methane (which contains carbon) from collisions with ocean-floor bodies, or comets. Researchers have also expressed uncertainty about how much carbon dioxide was present in the air, and how much it moved the oceans inside. The new study froze both the volcanic theory and the amount of carbon released into the air.

The research is directly relevant to today, said lead author Laura Haynes, who did research at Lamont-Doherty as a graduate student. “We want to understand how the Earth system is rapidly responding to CO.2 Now emissions, “she said.” Paytm is not the perfect analog, but it is the closest thing we have. Today, things are moving very fast. Haynes is now an assistant professor at Vassar College.

Ancient volcanoes once promoted ocean carbon, but humans are now removing them

Eight miles from Puerto Rico near the sea surface, Koathor occupies Bärbel Hönisch. The samples were brought back to the laboratory for incubation in controlled conditions. Credit: Laura Haynes / Lamont-Doherty Earth Observatory

So far, PETM’s oceanographic studies have relied on assumptions based on chemical data derived from the oceans, and to a certain degree of estimates that the researchers fed into computer models.

The authors of the new study received answers to more direct questions. They did this by cultivating small-edged marine organisms called foeminifera in seawater that resembled the highly acidic conditions of PETM. They recorded how organisms took element shells into their shells during development. They then compared these data to the analysis of fossil formafera in the Pacific and Atlantic Ocean-floor coromine, which extends the Paytm. This allowed them to identify carbon-isotope signatures associated with specific carbon sources. This indicated that volcanoes were the main source – possibly concentrated by large-scale eruptions that are now Iceland, as the North Atlantic Ocean opened up, and North North America and Greenland separated from Northern Europe.

Researchers say that carbon pulses, which last for at least 4,000 to 5,000 years, according to others, have added 14.9 quadrillion metric tons of carbon to the oceans – a two-thirds increase compared to their previous content. Carbon must have come from CO2 Directly emitted from explosions, combustion of surrounding sedimentary rocks, and some methane at depth well. As the oceans absorb carbon from the air, the water becomes highly acidic, and remains so for thousands of years. There is evidence that it killed life in very deep seas, and perhaps other sea creatures.

Today, human emissions are skyrocketing carbon dioxide in the atmosphere, and oceans are absorbing it again. The difference is that we are projecting it much faster than a volcano within decades instead of mating. Atmospheric levels have shot up from about 280 parts per million to around 415 in the 1700s today, and they are on track to keep growing rapidly. The atmospheric level would already be very high if the oceans were not absorbing too much. As they do, rapid acidification is beginning to emphasize marine life.

“If you add carbon slowly, living things can adapt. If you do it too fast, that’s a really big problem,” said Björl Hobisch, a geochemist at Lamont-Doherty. He said that even with the slow pace of Paytm, sea life witnessed major deaths. “The past saw some serious consequences, and it does not bode well for the future,” she said. “We’re getting ahead of the past, and the results are probably going to be very serious.”

Volcanic eruptions overcome ancient global warming phenomenon

more information:
Laura L. Haynes L. al., “Seawater Carbon List on Paleocene-Eocene Thermal Maximum,” PNAS (2020).

Provided by Earth Institute at Columbia University

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