ABSTRACT
Although climatic fluctuations have occurred often over the past 420,000 years, the rates of increase in temperature in the last 100 years are unprecedented in both magnitude and cause. Similarly, the rates of increase in atmospheric greenhouse gas (GHG) concentrations over the 20th century do not appear in the paleo record, and are causally linked with the recent changes in global temperature. Significantly, human industrial development is clearly linked to for the changes in GHG concentrations. Over much of the preceding half million years, the fluctuations of atmospheric GHGs and global average temperature remained in a relatively narrow, correlated band (Chapter 2), implying a natural balance in the exchange of GHGs between the atmosphere and planetary surface.1
