Tiny Bubbles Tell All

Our knowledge of long-term human effects on greenhouse gas levels in the atmosphere comes from air trapped in ice cores taken from polar ice sheets. These ice core samples allow researchers to place modern changes in the context of natural variations over hundreds of thousands of years. In his Perspective, [Brook][1] discusses results reported in the same issue by [ Siegenthaler et al .][2] and by [ Spahni et al .][3] based on new samples obtained by the European Project for Ice Coring in Antarctica (EPICA). The new long records of carbon dioxide, methane, and nitrous oxide from EPICA extend the window on greenhouse gas levels to 650,000 years. The results confirm that the modern atmosphere is highly anomalous and reinforce the view that greenhouse gases and climate are intimately related. [1]: http://www.sciencemag.org/cgi/content/full/310/5752/1285 [2]: http://www.sciencemag.org/cgi/content/full/310/5752/1313 [3]: http://www.sciencemag.org/cgi/content/full/310/5752/1317