The closest analog to modern times is no longer very close, the study finds.
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.
Researcher on Columbia UniversityThe Laumont-Doherty Earth Observatory investigated the state of the ocean 55.6 million years ago, a time known as the Paleocene – Eocene Thermal Maxim (PETM). Prior to this, the planet was already much warmer than today, and Paytm’s rising CO2 levels raised the temperature from 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 now going to respond to rapid CO2 emissions,” she said. “Paytm is not the right analog, but it is the closest thing we have. Today, things are moving very fast. Haynes is now an assistant professor at Vassar College.
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 the main source of volcanoes was – likely concentrated by the massive eruptions that are now Iceland, as the North Atlantic Ocean opened up, and North North America and Greenland were separated from Northern Europe.
Researchers say that carbon pulses, which others estimate lasted at least 4,000 to 5,000 years, added 14.9 quadrillion metric tons of carbon to the oceans – two-thirds increasing their previous content. Explosions of carbon must have come from explosions, combustion of sedimentary rocks directly around, and CO2 emitted by some methane from the 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 presenting it much faster than volcanoes for centuries – rather than millennia. 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, then living things can be favorable. If you do it too fast, it’s a really big problem, ”said study co-author Bärbel Hönisch, a geoscientist in 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.”
Reference: 14 September 2020, Proceedings of the National Academy of Science.