Two scientific reports released this year have used ice core samples from East Antarctica to detect greenhouse gas cycles of the past 650,000 years.

• Spahni, Renato et al. "Atmospheric Methane and Nitrous Oxide of the Late Pleistocene from Antarctic Ice Cores." Science 310(5752): 1317-1321. 25 November 2005 at www.sciencemag.org

• Siegenthaler, Urs et al. "Stable Carbon Cycle-Climate Relationship During the Late Pleistocene." Science 310(5752): 1313-1317. 25 November 2005 at www.sciencemag.org

The ice cores, sampled and analyzed by the European Program for Ice Coring in Antarctica, reveal the long-term glacial-interglacial cycles of the climate and provide records of atmospheric carbon dioxide, methane, and nitrous oxide for the time period. The researchers note that methane and carbon dioxide levels after the Industrial Revolution remain unmatched to any record during the 650,000 years before the Revolution.

Implications: It has often been asserted that the geological record contains previous cases where CO2 concentrations have risen to extraordinary heights -- with little or no concomitant climate change. This data makes clear that we have surpassed any previous data in terms of GHG concentrations -- and are, thus, in uncharted territory in terms of potential impacts and damages.