Our company recently started a go-green program and they've been posting lots of environmental facts in elevators, hallways, etc. Anyway, I don't know why I never thought about it before but it was only after reading one of those environmental facts that I realized that cellphones and laptops must produce so much greenhouse gases. Not only during usage but during production as well. In fact, I got so curious that I did a little bit of research and found this.
Smartphone charging spews out megatons of greenhouse gases