I guess that if you think the world is ending within one generation, then you might be disinclined to care about environmental issues that will cause problems for the next generation, or the one after. But "disinclination" doesn't begin to describe the outright hostility that conservative Christians appear to have for the issue.
The study of global warming is a relatively recent field -- compared with, say, evolution (150 years) or Newtonian physics (300 years) or even relativity and quantum mechanics (about 100 years). As such, it is a field particularly active in generating new data and interpreting what this data means. Like evolution, there is a scientific consensus on the big picture (global warming is real, it is a recent development, and it is in some significant way affected by worldwide human behavior) but the details are open to debate (i.e., what will be the particular short term and long term effects, and what policy actions should be enacted as a result).
This is a fundamentalist gold mine, because what anti-science religious folks love to do is highlight a particular controversy and then say "See? Science is unreliable because it's changing all the time!"
Case in point:
Noted Hurricane Expert Kerry Emanuel has publicly reversed his stance on the impact of Global Warming on Hurricanes. Saying "The models are telling us something quite different from what nature seems to be telling us," Emanuel has released new research indicating that even in a rapidly warming world, hurricane frequency and intensity will not be substantially affected.
"The results surprised me," says Emanuel, one of the media's most quoted figures on the topic.
From a scientific perspective, if you believe one thing and then later you recognize that you were mistaken based on new evidence, it's simply part of the process. It's an important component of intellectual integrity. Science changes, just like people do. In both cases, it's otherwise known as "learning new things." Dawkins sometimes admiringly tells the story of a scientist who profusely thanks the man who shows that he has long been in error about an important concept.
To a fundamentalist, on the other hand, this story is treated as an opportunity to dismiss the entire science of climate change. "Ah, so they were WRONG! Knowing this, how can we trust anything those scientists say?" In this frame, change is treated as a sign of weakness rather than a sign of improvement. While creationists often pay lip service to the importance of science ("Our beliefs should totally be taught in science classes, you Nazis!"), when science appears to contradict the Bible, they do more than argue against the theory; they denigrate science itself. I get the distinct impression that science is viewed as a threat because it is a competing method of knowing things in general.
I've heard numerous sermons -- some on the radio, some live -- where the theme appeared to be "Everything in life is garbage unless you have Jesus." Often repeated in this flavor of sermon are verses such as Isaiah 55:8-9:
"For my thoughts are not your thoughts, neither are your ways my ways," declares the LORD. "As the heavens are higher than the earth, so are my ways higher than your ways and my thoughts than your thoughts."
And 1 Corinthians 3:19:
For the wisdom of this world is foolishness with God. For it is written, He taketh the wise in their own craftiness.
Human knowledge is garbage. So says the Lord. And since we can't rely on our own poor knowledge, the default option available should be to look to the church for answers. If someone purports to say something that does not match what the church says, don't listen to them, for their ways are not His ways.
Then along comes science.
Science proposes a systematic, reliable, testable method for gaining more knowledge over time. It is not based on the Bible. It is not inherently hostile to religion; it just disregards religion completely in the pursuit of understanding the world.
That's not something the church can accept. It undermines authority-based teaching, and it removes the feeling of helplessness that Isaiah's words are meant to invoke.
So as a result, a large body of work has grown around the effort to frame science as simply a competing worldview, devoid of merit in its own right. It's not just fundamentalists who do this; post-modernist writers also get off on the idea that there is no such thing as reality. In their works, they reduce science to one of many "belief systems," neither better nor worse than any other way of understanding.
To paraphrase George Carlin: "Same as God. Same as the four leaf clover, the horse shoe, the rabbit's foot, and the wishing well. Same as the mojo man. Same as the voodoo lady who tells your fortune by squeezing the goat's testicles. It's all the same." (Carlin, of course, was not talking about science, but about offering prayers to Joe Pesci.)
Science is a threat to religious beliefs not only because it sometimes contradicts them, but because it offers a way to be correct without relying on supposed magic powers.