‘Unprecedented’: CO2 in the atmosphere is rising 10 times faster than at any point over 50,000 years

A slice from an Antarctic ice core.
A slice from an Antarctic ice core. Copyright Katherine Stelling/Oregon State University
Copyright Katherine Stelling/Oregon State University
By Rosie Frost
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Ice built up in the Antarctic over hundreds of thousands of years is helping scientists to understand today's climate.

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A detailed analysis of ancient Antarctic ice has revealed that carbon dioxide levels in the atmosphere are rising 10 times faster than at any point in the past 50,000 years.

Researchers at Oregon State University in the US and the University of St Andrews in Scotland looked at samples of ice collected by drilling cores up to 3.2km deep.

Ice has built up in the Antarctic over hundreds of thousands of years and includes atmospheric gasses trapped in air bubbles inside of this ice. Scientists look for trace elements in samples of this ice to build a record of what the climate was like in the past.

"Studying the past teaches us how today is different. The rate of CO2 change today really is unprecedented," says Kathleen Wendt, an assistant professor at Oregon State University's College of Earth, Ocean, and Atmospheric Sciences and the study's lead author.

“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.”

What can ancient ice tell us about climate change?

Previous research has shown that, during the last ice age which ended around 10,000 years ago, there were several periods where CO2 levels appeared to jump much higher than expected.

But Wendt says those measurements weren’t detailed enough to reveal the full nature of these rapid changes, limiting scientists’ ability to understand them.

“You probably wouldn’t expect to see that in the dead of the last ice age,” she explains.

“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.”

The team used samples from a segment of the continental ice sheet called the West Antarctic Ice Sheet Divide to investigate what happened during those periods. The pattern they found showed these jumps happened alongside cold intervals in the North Atlantic known as Heinrich events. These events are associated with abrupt climate shifts around the world.

“These Heinrich Events are truly remarkable,” says Christo Buizert, an 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 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.

The largest of these natural rises saw carbon increase by about 14 parts per million in 55 years with jumps occurring around once every 7,000 years. At current rates, that magnitude of increase only takes five to six years.

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