Here is a really scary looking chart - CO2 levels versus temperature of 40,000 years:
Figure 1: Fluctuations in temperature (blue) and in the atmospheric concentration of carbon dioxide (red) over the past 400,000 years as inferred from Antarctic ice-core records. The vertical red bar is the increase in atmospheric carbon dioxide levels over the past two centuries and before 2006. From A. V. Fedorov et al. Science 312, 1485 (2006). Exit EPA Disclaimer. Reprinted with permission of AAAS* Exit EPA Disclaimer.
