A dire report released Friday from an international panel of scientists highlights the human impact of global warming.
It predicts widespread hunger, thirst and disease if governments don't take aggressive action.
It's always hard to know what effect individual choices will have on the global environment, but a number of organizations are trying to make it more clear.
It's possible to calculate a "carbon footprint," how activities like driving a car and running the air conditioning, contribute to greenhouse gas emissions.
Travel writer and Minnesota-native Doug Lansky has been looking at ways to mitigate carbon emissions from the flights he takes around the globe. He says more and more travel Web sites are offering easy ways to do just that.