Since the Industrial Age spurred the increasing usage of fossil fuels for energy production, the weather has been warming. Despite some naysayers with alternative theories about why global temperatures are rising - including the idea that the earth goes through natural temperature cycles every few millennia - the dramatic changes in the earth's atmospheric makeup suggests humans are to blame. In fact, 97% of scientists agree humans are responsible for climate change. Since the Industrial Revolution, carbon dioxide levels increased 38% because of humans, methane levels have increased 148%, nitrous oxide is up 15%.