By Christopher Fenn, National Geographic News, Antarctica article A recent survey of ice cores in Antarctica’s Ice Cap by a group of scientists shows that the concentration of carbon dioxide in Antarctic ice has risen rapidly since the mid-20th century.
The study, published today in the journal Nature Communications, suggests that warming oceans will likely cause the carbon dioxide concentration to continue to rise.
“In the past two decades, Antarctic ice cover has gone from about 20,000 cubic kilometers (about 10,000 square miles) to around 60,000 to 80,000 km2,” said lead author and geochemistry professor Paul Goudy of the University of British Columbia in Vancouver, Canada.
“That’s a tremendous increase in the amount of carbon that’s floating around in the ocean, which is why we have to keep an eye on it.
It’s going to continue doing that.”
In fact, the researchers found that carbon dioxide levels have risen nearly 40 percent in the last century, with a doubling of the amount that can be found in ice cores.
In total, the scientists analyzed a sample of more than 20,500 cores that span between 18,000 and 26,000 years old, spanning the mid and late Holocene epoch.
“Ice cores tell us about the ocean conditions when carbon dioxide was stable,” said Goudi.
“They also tell us how much carbon has been floating around the world.”
To test their theory, the team analyzed ice cores from Antarctica’s McMurdo Sound Ice Shelf, a major ice shelf in the southern part of Antarctica.
The study found that the area has warmed significantly over the last two decades.
At the beginning of the study, the area’s ice thickness was around 1,400 square kilometers (300 square miles).
Today, the ice is about 8,000 kilometers (5,600 miles) thick, and is expected to continue warming due to climate change.
Goudy said the ice also contained a large amount of nitrogen.
The researchers believe that carbonate minerals in the ice are becoming less stable due to warming.
“They’re just starting to go into the ice and become less stable, and it’s a natural process,” said study co-author Robert Stapleton, an assistant professor of geological sciences at the University at Buffalo.
“It’s also a problem because the ice sheet is getting thicker, and they’re getting more and more unstable as time goes on,” he said.
Gould said it’s possible that the ice itself could be becoming unstable as well.
“We don’t know the extent to which the ice may be getting unstable, but we do know that if you can get more CO2 into the ocean from melting snow, you have more CO 2 in the water and more ice,” he explained.
Stapleton said the new study does not explain why Antarctic ice is getting more unstable.
“Our data does not show a causal relationship between rising CO2 and increasing ice loss,” he told National Geographic.
“But the ice does look to have gotten more stable over time.
The reason that we have this high level of carbon isotopes in the core is that we are seeing a trend towards a higher level of atmospheric CO2 over the past 200 years.”
The findings were a surprise to Gouds, because ice cores have previously suggested a negative relationship between carbon dioxide and ice.
“I think it’s more than coincidental that there has been a positive relationship between CO2 in the atmosphere and ice,” Goud said.
The team says that while their findings provide an indication of how much CO2 is in the world’s oceans, the amount is only a small fraction of the total amount that is stored in the Earth’s crust.
They also say that future research will be needed to determine how much of that CO2 could be stored in deep ocean, or how much is trapped in the glaciers that cover the ice shelves.
The researchers are also continuing their research to look at how much methane is being released from Antarctica as temperatures rise.
Godys research is supported by the National Science Foundation (NSF).