One of the most important components of climate changes is the level of carbon dioxide in the atmosphere. They greatly affect the average minimum temperature of the Earth and even very small changes in the amounts of Carbon Dioxide in the atmosphere can result in large changes in the average temperature of the Earth.
Another important factor is the presence of the Milankovitch Cycles. These are natural, normal, periodic, regular perturbations in Earth's orbit that over millions of year will bring it closer and farther from the Sun. The closer the Earth is to the sun, the warmer it will be and the farther away the Earth will be from the Sun, the cooler it will be. This is what causes the long-term, large-scale climate changes. Factors like carbon, volcanic ash and gasses, etc. work on much smaller time scales. The timing of the Milankovitch Cycles corresponds very well with all of the major ice age events, and in turn, the major warming events.
Thus, Carbon Dioxide and the Milankovitch Cycles are important causes of long-term climate change.
Climate change occurs because of the influx of greenhouse gases. The major gases responsible for the greenhouse effect are:
- water vapor
- carbon dioxide
- Nitrous oxide
- Chlorofluorocarbons (CFCs)
All save water vapor and CFCs are being rapidly added to the atmosphere by human activities. Combustion of fossil fuels releases carbon dioxide and nitrous oxide. Our agriculture system use CAFOs which release large amounts of methane. CFCs are largely regulated now and pose less of a threat. Although Methane has more warming power than carbon dioxide, there is less of it in the atmosphere. Therefore, the most problematic one is carbon dioxide.