Greenhouse-gas levels highest in 650,000 years

Two recent articles in Science magazine demonstrate that current CO₂ and methane levels in the atmosphere are higher than they have been at any time in the last 650,000 years. In the case of CO₂ the current level is about 375 ppm (parts per million). This is compared with a maximum of 290 ppm during the period between 390,000-650,000 years before present. In the case of methane, the current level is about 1700 parts per billion (ppb), as compared with an average of 600 ppb during the same historical period. Furthermore, Thomas Stocker of the University of Bern, who led the analysis of Antartic ice cores that provided this information said:

Atmospheric carbon dioxide levels have risen 200 times faster over the past 50 years than at any other time during this period.

This unprecedented rate of increase of greenhouse gas concentrations in the atmosphere puts the responsibility firmly on the shoulders of the human race. If we are driving this change, should we not therefore take it upon ourselves to reverse it?

References

Siegenthaler U., et al. Science, 310. 1313 - 1317 (2005).
Spahni R., et al. Science, 310. 1317 - 1321 (2005).