



The ice containing the record was recovered at a field camp in the center of West Antarctica, 1,040 km (650 miles) from the geographic South Pole, where the ice is more than 3,460 m (two miles) thick. In the new WAIS Divide core each of the past 30,000 years of snowfall can be identified in individual layers of ice. By allowing an examination of past climate at an annual resolution, the record will help scientists understand why climate can change abruptly—in less than 10 years—and how climate could unfold in the coming century.

Other ice-coring projects have produced cores of lower temporal resolution, showing that the current level of atmospheric greenhouse gases, which is due to the burning of fossil fuels, is the highest in at least 800,000 years. The ice that is between 30,000 and 68,000 years old—while not containing records with annual resolution—contains a higher time resolution record than previous projects.



The information from the project will be used to test and improve the predictions of how the current human-caused increases in greenhouses gases (for example, carbon dioxide, methane) are altering the earth's climate.

"The combination of being able to identify individual years and new analytical methods that were not available on previous projects will greatly improve our understanding of how past changes in greenhouse gases influenced the global climate," says Kendrick Taylor, of the Desert Research Institute, in Reno Nevada, and chief scientist for the WAIS Divide project.

He adds that it will take another two years to complete the analysis of the ice and publish the results.


In addition to collecting 3,405 m (11,160 ft) of a 12.2-cm (4.8-in) diameter ice core, a new directional-drilling procedure was developed that allowed the team to drill through the wall of the main hole and collect a total of 285 m (936 ft) of additional core from five of the most scientifically interesting time periods. This enables replication of the results and expands the suite of measurements that can be made on the most interesting ice.

This is the first time anyone has ever taken additional ice core out of the side of the borehole without blocking access to the lower part of the main borehole. It's an engineering breakthrough that will allow us to look in great detail at the causes of abrupt climate change," says Jeff Severinghaus of the Scripps Institution of Oceanography, chief scientist for replicate coring.


Source: National Science Foundation