Most scientists agree that people have contributed to the increase in atmospheric carbon dioxide through activities such as driving and deforestation, and in turn, that increase has led to some amount of warming on Earth. Experts disagree when it comes to the magnitude of that impact. When we burn fossil fuels or drive a car and generate carbon dioxide coming out of the exhaust pipe, the carbon dioxide doesn't get washed out very easily, and it tends to hang around for more than a century. Dr. Tom Wigley is among scientists who believe people are impacting climate change. A small fraction, maybe 20 or 30 percent, could be due to changes in the output of the sun, and an even smaller fraction could be due to internal factors that would occur even if there were not changes in the sun and no greenhouse gas changes.
Tans agrees the climate is changing because of human activity.
We are a geologic force on this planet. And I really shouldn't have to convince anybody that this is the case. When you are in an airplane and you look down, you can see what we're doing to the surface. We dominate the land. We've parceled it up into agricultural, into cropland, ranches.