Past Antarctic Warming Linked to Greenhouse Gas: Carbon Dioxide has Future Implications

Ever had your doubts about the fact that carbon dioxide levels cause global warming? Now, researchers have found past evidence for the phenomenon. A new study strongly suggests that the higher gas levels may have caused Antarctic warming in the past and, in consequence, current human-caused gas emission will lead to climate change.

The new study, published in the journal Science, examined evidence buried deep within the ice sheets of the Antarctic. Over eons, ice traps gas bubbles from the climate at different depths. Each year, a new layer of ice forms--think of the rings on a tree. The deeper the scientists search the ice, the older the gas trapped within it usually ice. The findings can reveal historical temperatures and allow researchers to better understand our ancient climate.

In the past, scientists using older techniques have found that increases in carbon dioxide occur after global warming rather than cause it. In order to test that theory, Federic Parrenin and colleagues examined five ice cores that had been drilled from Antarctica over the last 30 years. They focused on a time period that occurred between 20,000 to 10,000 years ago, when our planet warmed naturally and glaciers melted.

The scientists first measured the concentration of nigrogen-15 isotopes located at different depths in the ice core samples. They then compared the depth of the isotopes with the ice composition for all the cores in order to determine the distance between ice bubbles and ice from the same period.

What were the results? They found that global warming and carbon dioxide increase happened at the same time, debunking the previous theory that carbon dioxide rose after the fact. The findings provide more proof that carbon emissions cause global warming, and that the current warming trend is manmade.

"It makes it possible that CO2 was the cause-at least partly-of the temperature increase during the courses of the last glaciation," said Parrenin in an interview with LiveScience.

The findings, while deflating some climate skeptics, probably won't change how most scientists look at the current warming trend. More importantly, the research shows that in the past, the release of carbon dioxide and warming were locked in a feedback loop. That is, the more carbon dioxide that was released, the more the Earth warmed, which caused more gases to be released. If emissions aren't curtailed, it could mean dire consequences for our warming planet.