Vostok Core

RUSSIA'S VOSTOK STATION is located in east Antarctica. Vostok Station holds the record for lowest temperature ever recorded at minus 129 degrees F (minus 89 degrees C). Soviet researchers began deep drilling at the Vostok Station in 1980. The ice cores brought to the surface in segments provide information (chemistry, structure, inclusions) about climate conditions similar to tree ring samples. The information from air bubbles allows for measurement of the atmospheric concentration of greenhouse gases (carbon dioxide, methane, nitrogen, helium, sodium, and organic carbon). Besides presenting an extraordinary human effort spanning two decades in one of the most inhospitable places on earth, the drilling at Vostok has produced one of the richest scientific treasure troves of all time. Previously, analysis revealed tracking between carbon dioxide and temperature and that the magnitude of the carbon dioxide swings could account for the magnitude of the temperature swings.

The first hole drilling stopped in 1985 because of problems. A second hole drilled with French-Russian cooperation produced an ice core 2,083 m. long, or 1.33 mi. With a climate record of 160,000 years, drilling on this hole ended in 1990. A third hole was drilled with collaboration among Russia, France, and the United States. The drilling reached a depth of 2.25 mi. (3.6 km.) and in January 1998 produced the deepest ice core recovered at the time (now exceeded by the European Project for Ice Coring in Antarctica)—11,886 ft. (3,623 m.) deep, containing a climate record of 420,000 years, for a total of four climate cycles. Drilling stopped at this depth because the researchers were recovering accretion ice refrozen to the bottom of the glacier, indicating the presence of an underlying lake, and did not want to put themselves in danger from the release of pressurized lake water or risking contamination of the lake. Researchers have found microbes in the glacial ice from the Vostok core and four times more in the glacial-accretion ice transition, suggesting that the underground lake contains microbes and organic carbon.

Polar snowfall can be preserved in annual layers within an ice sheet to provide a climate record. These layers can be studied to develop an accurate picture of the climate history extending over the time periods (the deepest Vostok core extends over a 400,000 year time frame). Impurities (volcanic debris, sea salt, organic material, and interstellar particles) are also deposited with snow, making those layers distinctive.

Air bubbles trap gases in the ice and allow for testing to determine the air's composition at distinctive periods in the climate record. Water pockets may also become trapped the deeper the ice core is, and closer to the underlying rock or water. Researchers can determine the composition of water in comparison with heavy water isotopes to indicate environmental temperature; cold periods are those with moisture being removed from the atmosphere.

Studies on the second Vostok core showed a correlation between carbon dioxide and temperature over the past 160,000 years and provided evidence linking climate change with the greenhouse effect. The trapped air bubbles provided gas isotopes and, when compared with the temperature variations, matched up to show that greenhouse gases were the primary driver of climate change over time. The climate variation of ice ages also matched the solar records.

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