Global warming occurs when the levels of greenhouse gasses rise and less infrared light, or heat, escapes the earth's atmosphere. Thus, the temperature experienced on Earth begins to rise.
Climate change is a part of the Earth's history.
There have been dramatic fluctuations in overall average temperature for the past 150,000 years that suggest a direct association with carbon dioxide levels. In the past the temperature highs and lows have been in tandem with carbon dioxide level highs and lows, this does not seem to be a mere coincidence. However, it has a disproportionate impact on the earth's temperature. Thus, minor fluctuations in the percentage of atmospheric carbon dioxide will likely have a significant effect on the global temperature. The percentage of atmospheric carbon dioxide has risen over the past century at an alarming rate.