The League of Conservation Voters has a legislative scorecard, covering the first session of the 112th Congress (2011). Here are the scores of Minnesota's delegation, from first to worst - from the standpoint of progressive environmentalism, that is.
Keith Ellison 91%
Al Franken 91%
Tim Walz 83%
Amy Klobuchar 82%
Betty McCollum 74%
Erik Paulsen 29%
Collin Peterson 20%
Chip Cravaack 14%
John Kline 9%
Michele Bachmann 6%
I have no additional comment; the numbers speak for themselves, or, rather, those that produced them. You can check everything out here.