Atmospheric CO2 Increasing 10x Faster Than in Last 50,000 Years, Study Finds

Carbon dioxide is increasing in the atmosphere 10 times faster than it has in the last 50,000 years, according to a new study led by researchers from University of St. Andrews and Oregon State University.

The findings shed light on periods of abrupt climate change in the planet’s history while offering new understanding of the impacts of today’s climate crisis.

“Studying the past teaches us how today is different. The rate of CO2 change today really is unprecedented,” said Kathleen Wendt, lead author of the study and an Oregon State University assistant professor in the College of Earth, Ocean and Atmospheric Sciences (CEOAS), in a press release from University of St. Andrews. “Our research identified the fastest rates of past natural CO2 rise ever observed, and the rate occurring today, largely driven by human emissions, is 10 times higher.”

The international research team conducted a detailed analysis of the chemicals in ancient Antarctic ice, which showed the impact of human carbon emissions.

Over hundreds of millenia, ice containing gases from the atmosphere trapped in air bubbles built up in Antarctica. Scientists drill cores as deep as two miles in order to take samples of the ice, analyze trace chemicals and put together records of the climate of the past.

Prior research revealed that the last ice age — which came to an end roughly 10,000 years ago — contained several periods during which carbon levels appeared to spike. However, Wendt said the measurements didn’t contain enough detail to show the complete picture of the changes, hampering scientists’ ability to comprehend what was going on.

“You probably wouldn’t expect to see that in the dead of the last ice age,” Wendt said in the press release. “But our interest was piqued, and we wanted to go back to those periods and conduct measurements at greater detail to find out what was happening.”

Using samples from the ice core of the West Antarctic Ice Sheet Divide, the team found a pattern showing that the sharp increases in carbon dioxide occurred alongside cold intervals in the North Atlantic — known as Heinrich Events — associated with abrupt global climate shifts.

“These Heinrich Events are truly remarkable,” said Christo Buizert, co-author of the study and an associate professor with CEOAS, in the press release. “We think they are caused by a dramatic collapse of the North American ice sheet. This sets into motion a chain reaction that involves changes to the tropical monsoons, the Southern hemisphere westerly winds and these large burps of CO2 coming out of the oceans.”

Carbon increased by approximately 14 parts per million during the 55 year period of the most prominent of the natural rises, and the spikes happened roughly once every 7,000 years. Today that magnitude of increase only takes from five to six years.

The evidence suggested that during the periods of natural increase, westerly winds integral to deep ocean circulation were also getting stronger, bringing about a quick release of carbon from the Southern Ocean.

“These Heinrich Events kick off an astonishing sequence of rapid shifts in climate around the world,” said co-author of the study Dr. James Rae of the University of St. Andrews School of Earth and Environmental Sciences. “They start with a weakening of the North Atlantic’s circulation system, which causes rapid cooling in NW Europe, sea ice expansion from Scotland to New York, and disruption to tropical monsoons. Our paper shows they also change winds and circulation in the ocean round Antarctica, which belches out CO2.”

The study, “Southern Ocean drives multidecadal atmospheric CO2 rise during Heinrich Stadials,” was published in the journal Proceedings of the National Academy of Sciences.

Previous studies have suggested that climate change will cause westerly winds to get stronger over the course of the next century. The researchers noted that, if that happens, their findings suggest the Southern Ocean’s ability to absorb human-generated carbon will be reduced.

“We rely on the Southern Ocean to take up part of the carbon dioxide we emit, but rapidly increasing southerly winds weaken its ability to do so,” Wendt said.