Creationism v Enviromentalism

Eric emailed me the link to an article in The New Republic a few days ago, but I'm just now getting a chance to read the whole thing.
It's an open letter to pastors from a scientist:

Still, for all the positive signs, I remain puzzled that so many religious leaders have hesitated to make protection of the Creation an important part of their magisterium. Pastor, help me understand: Do they believe that human-centered ethics and preparation for the afterlife are the only things that matter? Do they believe that the Second Coming is imminent and that, therefore, the condition of the planet is of little consequence? These and other similar doctrines are not gospels of hope and compassion. They are gospels of cruelty and despair.
You and I are both humanists in the broadest sense: Human welfare is at the center of our thought. So forget our disagreements, I say, and let us meet on common ground. That might not be as difficult as it first seems. When you think about it, our metaphysical differences have remarkably little effect on the conduct of our separate lives. My guess is that you and I are about equally ethical, patriotic, and altruistic. We are products of a civilization that rose from both religion and the science-based Enlightenment. We would gladly serve on the same jury, fight the same wars, and sanctify human life with the same intensity. Surely we also share a love of the Creation--and an understanding that, however the tensions play out between our opposing worldviews, however science and religion wax and wane in the minds of men, there remains the earthborn yet transcendental obligation we are both morally bound to share.

Do Christians and evangelicals have an obligation to care for the planet and worry about enviromental concerns? And if so, why have we not in the past? Does it revolve around the "liberal enviromentalist wacko" and "conservative tree killer" labels?
Take a moment to read the article and let me know what you think.