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Recent research indicates that the current rate of increase in atmospheric CO2 is unprecedented, being ten times faster than any period in the last 50,000 years, highlighting significant implications for global climate dynamics and the future CO2 absorption capabilities of the Ocean. Southern.
Researchers conducting detailed chemical analysis of ancient Antarctic ice have found that the current rate of increase in atmospheric carbon dioxide is 10 times faster than at any time in the past 50,000 years.
The findings, recently published in the proceedings of the National Academy of SciencesThey provide important new understanding of periods of abrupt climate change in Earth’s past and offer new insight into the potential impacts of current climate change.
“Studying the past teaches us how today is different. The CO rate2 The current change is truly unprecedented,” said Kathleen Wendt, assistant professor in the College of Earth, Ocean and Atmospheric Sciences at Oregon State University and lead author of the study.
“Our research identified the fastest rates of natural CO2 increase ever observed in the past, and the rate occurring today, driven largely by human emissions, is 10 times greater.”
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 due to the greenhouse effect. In the past, levels have fluctuated due to ice age cycles and other natural causes, but today they are rising due to human emissions.
Analysis of ice cores in Antarctica
The ice that 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 up to 3.2 kilometers (2 miles) deep, to analyze chemical traces and build records of past climate. The U.S. National Science Foundation supported the ice coring and chemical analysis used in the study.
Previous research showed that during the last ice age, which ended about 10,000 years ago, there were several periods when carbon dioxide levels seemed to jump 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.
A piece of an ice core from Antarctica. Researchers study chemicals trapped in old ice to learn about past climate. Credit: Katherine Stelling, Oregon State University
“You probably wouldn’t expect to see something like that in the last ice age,” he said. “But our interest was piqued and we wanted to go back to those periods and make measurements in greater detail to find out what was happening.”
Using ice core samples from the West Antarctic Ice Sheet Division, Wendt and his colleagues investigated what was happening during those periods. They identified a pattern showing that these jumps in carbon dioxide occurred alongside cold North Atlantic intervals known as Heinrich Events that are associated with abrupt climate changes around the world.
“These Heinrich events are truly remarkable,” said Christo Buizert, associate professor in the School of Earth, Ocean and Atmospheric Sciences and co-author of the study. “We believe they are caused by a dramatic collapse of the North American ice sheet. This sets in motion a chain reaction involving changes in tropical monsoons, southern hemisphere westerlies, and these big CO belches.2 coming out of 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 occurred about once every 7,000 years. At the current rate, that magnitude of increase takes only 5 to 6 years.
Evidence suggests that during past periods of natural carbon dioxide increases, westerly winds that 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 westerlies will strengthen over the next century due to climate change. The new findings suggest that if that happens, the Southern Ocean’s ability to absorb man-made carbon dioxide will be reduced, the researchers noted.
“We depend on the Southern Ocean to absorb some of the carbon dioxide we emit, but rapidly increasing southerly winds weaken its ability to do so,” Wendt said.
Reference: “The Southern Ocean drives atmospheric CO for several decades2 increase 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
Additional co-authors include Ed Brook, Kyle Niezgoda and Michael Kalk of Oregon State; Christoph Nehrbass-Ahles University of Bern in Switzerland and the National Physical Laboratory of the United Kingdom; Thomas Stocker, Jochen Schmitt and Hubertus Fischer of 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 of the University of Reading in the United Kingdom and Shaun Marcott of the University of Wisconsin-Madison.
The study was funded by the US National Science Foundation.