Is global warming for real?!?

The planet has gone through many dramatic climate shifts throughout history. This does not mean, however, that the phenomenon of global warming is not real or that it is not man-made (or, at least, that the effects are not greatly exaggerated by human activity). The fact is that humans have been burning fossil fuels for energy production for the past 150+ years, which produces carbon dioxide, a gas that traps heat. The more CO2 in the atmosphere, the more the atmosphere traps the sun's heat, which warms the planet. It is incredulous to argue that humans could be changing the chemical composition of the atmosphere of our planet without causing dramatic changes to global environmental systems.