Even though the temperature of the surface of the earth has been in the stability field of liquid water for nearly all of earth’s history, we know from worldwide glacial events that earth’s temperature and its climate has changed substantially during earth history. The ideas claimed by scientists to explain this include Milankovitch Cycles, Solar output changes, Movements of continents, Variation of atmospheric greenhouse gases, Ocean Circulation and Volcanic Eruptions.
What is different now is that we can see in earth science that man is affecting the earth systems by his activity. Most scientists agree that a link exists between climate change and man, mainly through the burning of fossil fuels (oil, gas, coal). We are now measuring global change indicators.
So natural change of climate is not the only force in action. We have to think about man’s influences because to some degree we can modify them. This is what drives the public’s interest in global warming--how will it affect my life, and can we do things to mitigate bad effects of climate change?
