“Unprecedented” – CO2 is rising 10 times faster than ever before in history

SciTechDaily
Carbon dioxide stack capture

Recent research shows that the current rate of atmospheric CO2 increase is unprecedented, ten times faster than any period in the past 50,000 years, highlighting significant implications for global climate dynamics and the future CO2 absorption capacity of the Earth. Southern Ocean highlighted.

Researchers who conducted a detailed chemical analysis of ancient Antarctic ice have found that the current increase in carbon dioxide in the atmosphere is ten times faster than at any time in the past 50,000 years.

The findings, just published in the Proceedings of the National Academy of Sciencesprovide important new insight into abrupt periods of climate change in Earth’s past and provide new insight into the potential impacts of climate change today.

“Studying the past teaches us how things are different today. The rate of CO2 The current change is truly unprecedented,” said Kathleen Wendt, assistant professor at Oregon State University’s College of Earth, Ocean, and Atmospheric Sciences and lead author of the study.

“Our research has identified the fastest natural CO2 increase in the past ever observed, and the rate occurring today, largely driven by human emissions, is ten times faster.”

Carbon dioxide, or CO2, is a greenhouse gas that occurs naturally in the atmosphere. When carbon dioxide enters the atmosphere, it contributes to climate warming through the greenhouse effect. In the past, levels fluctuated due to ice age cycles and other natural causes, but today they are rising due to human emissions.

Ice core analysis in Antarctica

Ice that has built up in Antarctica over hundreds of thousands of years includes ancient atmospheric gases trapped in air bubbles. Scientists use samples of that ice, collected by drilling cores up to 2 miles (3.2 kilometers) deep, to analyze the trace chemicals and build records of past climate. The U.S. National Science Foundation supported the ice core drilling and chemical analysis used in the study.

Previous research found that during the last ice age, which ended about 10,000 years ago, there were several periods when carbon dioxide levels appeared to be much higher than average. But those measurements were not detailed enough to reveal the full nature of the rapid changes, limiting scientists’ ability to understand what was happening, Wendt said.

Slice from an Antarctic ice core

A slice of an Antarctic ice core. Researchers study the chemicals trapped in old ice to learn about past climate. Credit: Katherine Stelling, Oregon State University

“You probably wouldn’t expect that in the dead of the last ice age,” she said. “But our interest was piqued and we wanted to go back to those periods and make more detailed measurements to find out what was going on.”

Using samples of the ice core from the West Antarctic Ice Sheet Divide, Wendt and colleagues investigated what happened during those periods. They identified a pattern showing that these jumps in carbon dioxide occurred alongside cold intervals in the North Atlantic Ocean known as Heinrich Events, which are linked to abrupt climate shifts around the world.

“These Heinrich events are truly remarkable,” said Christo Buizert, associate professor in the College of Earth, Ocean, and Atmospheric Sciences and co-author of the study. “We think they are caused by a dramatic collapse of the North American ice sheet. This sets off a chain reaction that involves changes in the tropical monsoons, the southern hemisphere westerly winds and these large amounts of CO2.2 come from the oceans.”

Comparison of natural and current CO2 increases

During the largest of the natural increases, carbon dioxide increased by about 14 parts per million in 55 years. And the jumps happened about once every 7,000 years. At the current rate, that magnitude of increase will only last five to six years.

There is evidence that during previous periods of natural carbon dioxide rise, westerly winds, which play an important role in deep ocean circulation, also strengthened, leading to rapid release of CO2 from the Southern Ocean.

Other research has suggested that these westerly winds will strengthen over the next century due to climate change. The new findings suggest that if that happens, it will reduce the Southern Ocean’s ability to absorb human-generated carbon dioxide, the researchers noted.

“We depend on the Southern Ocean to absorb some of the carbon dioxide we emit, but rapidly increasing southerly winds are weakening its ability to do so,” Wendt says.

Reference: “The Southern Ocean drives multidecadal atmospheric CO22 rise during Heinrich Stadials” by Kathleen A. Wendt, Christoph Nehrbass-Ahles, Kyle Niezgoda, David Noone, Michael Kalk, Laurie Menviel, Julia Gottschalk, James WB Rae, Jochen Schmitt, Hubertus Fischer, Thomas F. Stocker, Juan Muglia, David Ferreira, Shaun A. Marcott, Edward Brook and Christo Buizert, May 13, 2024, Proceedings of the National Academy of Sciences.
DOI: 10.1073/pnas.2319652121

Other co-authors include Ed Brook, Kyle Niezgoda and Michael Kalk of Oregon State; Christoph Nehrbass-Ahles of the University of Bern in Switzerland and the National Physical Laboratory in the United Kingdom; Thomas Stocker, Jochen Schmitt and Hubertus Fischer from the University of Bern; Laurie Menviel of the University of New South Wales in Australia; James Rae of the University of St. Andrews in the United Kingdom; Juan Muglia from Argentina; David Ferreira from the University of Reading in the United Kingdom and Shaun Marcott from the University of Wisconsin-Madison.

The research was funded by the US National Science Foundation.

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