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Ice Capades At the Ends of the Earth

A mile-and-a-half-long ice cube tells a story about Earth's climate.

In December 2008, our Michael Haederle reported on a study from West Antarctica that used ice cores to understand the relationship between carbon dioxide and climate change.

One of the goals of that project was to compare the Antarctic ice to that from Greenland in the Northern Hemisphere, where scientists have been drilling ice cores since 1971.

In the latest news from Greenland, an international team of 300 scientists and students drilling in the ice sheets of the northwest part of the country reached bedrock — at 1.5 miles deep — on July 27 after two years of work. (In Antarctica, the core was 2.2 miles long.)

The North Greenland Eemian Ice Drilling project is a collaboration of 14 participating nations — the most international ice core effort to date.

The scientists' samples dated back to the last interglacial period, 115,000 to 130,000 years ago, when temperatures were between 3.6 and 5.4 degrees Fahrenheit above those found today. Scientists will analyze impurities, greenhouse gas compounds, biological content and isotope ratios found in the packed snow samples for past temperatures and precipitations levels analogous to future climate change estimates. Data should help to improve climate scientists' understanding of the risks of abrupt change on a warming Earth.

"Ice core research has already provided convincing evidence of human-caused climate change by demonstrating a carbon dioxide-climate link," Haederle wrote. "In the past few hundred years, carbon dioxide concentrations have increased by 35 percent — far faster than at any time in the climate record — and temperatures appear to be rising quickly."