Science – Past carbon effects suggest future climate scenarios – Publimetro México

Madrid, 16 (European press)

A brief episode of warming caused by the explosion of carbon emissions, prelude to a period of extremes of heat 56 million years ago, is related to the change in the current climate.

The new findings, published in Science Advances, indicate that the amount of carbon released into the atmosphere during this precursor lower than the so-called Paleocene-Eocene Thermal Maximum (PETM) was roughly the same as the current cumulative carbon emissions from combustion. other human activities.

Thus, the short-lived precursor event represents what would happen if current emissions could be stopped quickly, while more extreme global warming for MTBE shows the consequences of continuing to release carbon into the atmosphere at the current rate.

Co-author James Zakos, Professor of Earth and Planetary Sciences and Ida Benson Lane Chair in Ocean Health at UCLA, said the UC Santa Cruz statement. If we stop emissions today, this carbon will end up mixing in the deep sea and its signals will disappear, because the deep sea reservoir is huge.”

This process would take hundreds of years, which is a long time by human standards, but short compared to the tens of thousands of years it took the Earth’s climate system to recover from the extremes of PETM.

The new findings are based on analysis of marine sediments that were deposited in shallow waters along the Atlantic coast of the United States and are now part of the Atlantic Coastal Plain. At the time of the MTPE, sea level was higher and much of Maryland, Delaware, and New Jersey was underwater. The US Geological Survey (USGS) excavated sediment cores from this area that the researchers used in the study.

MTPE in marine sediments is characterized by a significant change in carbon isotope composition and other evidence of drastic changes in ocean chemistry as a result of the uptake of large amounts of carbon dioxide from the atmosphere.

Marine sediments contain the microscopic shells of tiny marine creatures called foraminifera that live in the surface waters of the oceans. The chemical composition of these shells records the environmental conditions in which they formed and reveals evidence of rising surface water temperatures and ocean acidification.

The first author, Tali Babila, started the study as a postdoctoral fellow working with Zacos at the University of Santa Cruz and is now at the University of Southampton, UK. New analytical methods developed in Southampton enabled researchers to analyze the isotopic composition of boron in individual foraminifera to reconstruct a detailed record of ocean acidification. This was part of a suite of geochemical analyzes they used to reconstruct the environmental changes during the major precursor and MTPE event.

“In the past, thousands of fossil foraminifera shells were needed to measure boron isotopes. Now we can analyze a single shell the size of a grain of sand,” explains Babila.

Hints of precursor heating have been discovered in sediments in the continental section of the Big Horn Basin in Wyoming and a few other places. However, it was not clear whether this was a global signal, as it was absent in the deep-sea sediments core.

This makes sense because deep ocean sedimentation rates are slow, and the signal from a short-lived event would be lost due to the mixing of sediments with bottom-dwelling marine life, Zakus explains.

“The best hope of seeing the signal would be in shallow sea basins, where sedimentation rates are high,” he said. The problem there is that accidental deposition and erosion are most likely. So there is not much chance of him getting infected.”

The USGS and other agencies have drilled many sediment samples (or sections) along the Atlantic coastal plain. The researchers found that MTPE is present in all of these divisions, and several of them also capture the precursor event. The new study focuses on two parts of Maryland – at the South Dover Bridge and at Cambridge Dover Airport.

“We have the full signal here, and two other sites are capturing part of it. We think it’s the same event that they found in the Bighorn Basin,” says Zakus.

Based on their analyzes, the team concluded that precursor signaling in the Maryland sections represented a global event that likely lasted a few centuries, or perhaps several thousand years at most.

Two carbon pulses–the short-lived precursor and the larger, longer-lived carbon emissions that drove the MTBE–led to completely different mechanisms and timescales for the restoration of the Earth’s carbon cycle and climate system.

Carbon absorbed by surface waters during the precursor event was mixed into the deep ocean in about a thousand years. However, carbon emissions through MTPE have exceeded the buffering capacity of the oceans, and removal of excess carbon relies on much slower processes, such as weathering of silicate rocks over tens of thousands of years.

Zakos notes that there are important differences between the Earth’s climate system today and during the Paleocene, particularly the presence of the polar ice caps today, which increases the climate’s sensitivity to global warming.