Having children is the surest way to send your carbon footprint soaring, according to a new study from statisticians at Oregon State University.

http://oregonstate.edu/ua/ncs/archives/2009/jul/family-planning-major-environmental-emphasis

If people had only enough children to replace themselves, then there would be no population growth and the net effect on the environment could be regulated to a certain degree.  Not only is overpopulation bad for the environment, it's bad for us as a species because it means less and less resources (food, water, etc.) for us to survive on.

I could have told them this for a buck. How much did this study cost?