¥2 most important greenhouse gases: H2O, CO2
¥Man is modifying the CO2 concentrations via burning
fossil fuels
¥CO2 concentrations are higher than any time in the last 400,000 years (NOAA site).
–Amounts are now beyond the range of natural variations experienced over the past 700,000 years
¥Predictions are for CO2 concentrations to continue increasing to 1.5 to 3 times
present values by 2100 (NOAA site)