In the past 150,000 years there have been many significant fluctuations in the atmospheric CO2 concentrations. CO2 is the predominant greenhouse gas, and accounts for about two thirds of the human induced warming effect. Nitrous oxide and other gases account for the rest.

Up until the industrial revolution, these natural fluctuations were in the range of 180-280 parts per million (ppm). In the last 200 years the concentration of CO2 has increased to approximately 380 ppm. As the CO2 level has increased so has the climate. In the past 100 years the earth’s climate has warmed by 33 degrees Fahrenheit.

Human activities have altered the chemical composition of the atmosphere as greenhouse gases build. As this occurs, rain and snowfall patterns change, sea levels rise and mountain glaciers in non-polar regions retreat.