2-mile ice core shows climate fluctuation

Cylinders of ice from a two-mile long ice core collected from the West Antarctic Ice Sheet are providing evidence for rapid climate fluctuations during the Earth’s last glacial period, tens of thousands of years ago, according to a paper published in Nature on April 29. An analysis of the ice’s methane and sea-salt content, and the isotope content of the melted ice, points to a climate transitioning from a relatively warm to a relatively cold period in less than 20 years, a team of scientists based in Nevada’s Desert Research Institute has found.

Scientists collected the 4.8-inch diameter ice core at a field camp in the center of western Antarctica, about 650 miles from the geographic North Pole.

A comparison with ice-core evidence from Greenland indicates that the Arctic and Antarctic climates alternated between warm and cold periods, with the Antarctic warming as Greenland was cooling, and vice versa. Scientists attribute this phenomenon to the heat transfer impacts of ocean currents, with these currents carrying heat between the Earth’s northern and southern hemispheres.

“These past climate changes are different from what is happening today,” said the study’s lead author Christo Buizert, a postdoctoral researcher at Oregon State University. “The abrupt climate changes during the ice age were regional in scope and caused by large-scale changes in ocean circulation. The changes in temperature and precipitation that are occurring now are global and primarily caused by increasing levels of carbon dioxide in the Earth’s atmosphere.”

However, Buizert said that the new observations can help test and improve the global climate models that are used to predict future climate warming trends.

- Alan Bailey