At the moment, the official White House energy policy seems to be "Burn Oil" or, perhaps, "Burn Oil And Ignore All Consequences".

I see two main problems with our lack of energy policy, both of which end up hurting US security. First, global warming. Second, burning oil ends up enriching many people who are not our friends.
Second things first. We don't have any choice in the matter, of course, because two thirds of the proven oil reserves out there are in Saudi Arabia, Iraq (which may well turn out to have more oil than even the Saudis), the United Arab Emirates, Kuwait, and Iran (followed by Venezuela, Russia, and Libya, so it's not like there are other friendlies out there either). As we constitute of 25% of the world's oil consumption, we are in fact subsidizing the governments of these countries. (Do Russia and Venezuela count as democracies? Moreso than the others, I guess...) None of these countries are friendly to us. Although some members of the House of Saud like us, the evidence seems pretty clear that many more of them don't. We would be well off, as a matter of national security, to try to cut our oil consumption and stop sending money to the tyrants running these countries.

Global warming is an entirely different problem, but similar in that the danger lies in the future, maybe ten or twenty years. Even if the White House insists on sticking its head in the sand, the scientific evidence in favor of the greenhouse effect is overwhelming. This isn't a problem for the earth, because over time the climate has changed sporadically. The earth will be fine. It's a problem because humans have invented property rights and boundaries. I think the key to the danger is that the US is endangered by instability. Unstable countries can become what was Afganistan, i.e. breeding grounds and training camps for those who don't like us. So to pick an obvious example, if Bangladesh floods more frequently due to increased sea levels, or if Pakistan produces less food because it's even drier, these countries are apt to become less stable.
I actually don't think the effects of global warming on the US directly will be so bad. I mean, if North Carolina's outer banks disappear or the Great Plains revert to arid semi-desert, the US would suffer, but we'd get by (Scot, sorry about Kansas). But the risk to our national security from other countries is really dangerous.