Our environment is in trouble. It's not hard to imagine global catastrophe as problems like climate change and overpopulation take their toll. But there's always hope and in this hour of To the Best of Our Knowledge, we'll introduce you to the visionaries who are making a difference. Like Wangari Maathai, who won a Noble Peace Prize for her extraordinary efforts to plant trees in Kenya. And Geir Haarde, the former President of Iceland, whose country is now running on over eighty percent green energy.