If you're from the US and the environment is a major factor in your voting decisions, you may just want to stay away from John McCain, at least according to the League of Conservation Voters' environmental scorecard:
The scorecards, which rank individual U.S. legislators based on their votes on environmental issues, focused on 15 votes this year--all of which senator McCain missed, resulting in a 0% score.
Presidential candidates historically suffer from absenteeism, due to busy campaign schedules that keep them away from Washington. However, Obama and Clinton both missed only 4 environmental votes, and received scores of 67% and 73% respectively.
McCain's lifetime average, as scored by LCV, is 24%, far below Obama's 86% lifetime average and Clinton's 87% lifetime average.