Well if you believe the world is 6,000 years old, you'll reject all of the evidence of ice cores and all that.
A lot of evangelicals also believe that God created the Earth for humans to use and that we can't possibly to any lasting damage to it.
If Catholics and Mainliners don't believe those things* then why isn't there a considerable difference between them and evangelicals on this issue?
* Of course, young earth creationism doesn't characterize all of evangelicalism by any means.
Keep in mind that a lot of mainliners live in the more Northern states, and if you're asked a question about global warming during the frigid winter/late fall months, you're probably less likely to respond favorably to it.
