The surprising relationship between Earth’s orbital patterns and a paleo-warming event

An international team of scientists has found that changes in Earth’s orbit favoring hotter conditions may have helped trigger the rapid global warming known as the Paleocene-Eocene Thermal Maximum (PETM) 56 million years ago.

An international team of scientists has suggested that changes in Earth’s orbit that led to warming may have played a role in triggering the rapid global warming that occurred 56 million years ago. This event, known as the Paleocene-Eocene Thermal Maximum (PETM), is an analogue of modern-day climate change.

said Lee Kump, professor of geosciences at Penn State University. “There has been a lot of interest in finding a better resolution of this history, and our work addresses important questions about the cause of the event and the rate of carbon emissions.”

The team of scientists studied core samples from a well-preserved record of the PETM near the Maryland coast using tulipology, a method of dating sedimentary layers based on orbital patterns that occur over long periods of time, known as Milankovitch cycles.

Penn State is working on a core sample

Victoria Fortes (right), then a graduate student at Penn State, and Jean Self Trail, a USGS research geologist, work on a core sample from the Howards Tract site in Maryland. Credit: Pennsylvania

They found that the shape of Earth’s orbit, or eccentricity, and wobble in its rotation, or magnitude, favored warmer conditions at the beginning of the Betem period and that together, these orbital configurations may have played a role in triggering the event.

“The tropical trigger may have triggered the release of carbon that caused several degrees of warming during the PETM period rather than the currently more popular explanation that supervolcanoes released carbon and triggered the event,” said Coombe, John Lyon, Dean of the School of Geosciences. and minerals.

The results published in the journal

Erosion from the paleo Potomac and Susquehanna rivers, which at the onset of the PETM may have rivaled the discharge of the Amazon River, carried sediments to the ocean where they were deposited on the continental shelf. This formation, called the Marlboro Clay, is now inland and offers one of the best-preserved examples of the PETM.

“We can develop histories by coring down through the layers of sediment and extracting specific cycles that are creating this story, just like you could extract each note from a song,” Kump said. “Of course, some of the records are distorted and there are gaps — but we can use the same types of statistical methods that are used in apps that can determine what song you are trying to sing. You can sing a song and if you forget half the words and skip a chorus, it will still be able to determine the song, and we can use that same approach to reconstruct these records.”

Reference: “Astrochronology of the Paleocene-Eocene Thermal Maximum on the Atlantic Coastal Plain” by Mingsong Li, Timothy J. Bralower, Lee R. Kump, Jean M. Self-Trail, James C. Zachos, William D. Rush and Marci M. Robinson, 24 September 2022, Nature Communications.
DOI: 10.1038/s41467-022-33390-x

The study was funded by the National Key R&D Program of China and the Heising-Simons Foundation.

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