I've read a number of things lately (particularly on Motl's blog) suggesting that maybe anthro-centric climate change doesn't exist, or that if it does the effects are small in comparison with natural variations caused by things like natural disasters and long-term solar cycles. This is certainly not a mainstream point of view amongst climate scientists, but Motl does make some interesting points that I have yet to see refuted.
However, even if Motl is right that still doesn't exuse us from having to invest in alternative energy sources, because fossil fuels are still running out. They've been getting more and more expensive for years and it's not because of the price of the dollar or the greed of oil companies - it's simply that we've already used up the oil that is cheap to extract, and what remains is more labour-intensive and therefore more expensive. This trend will continue until it becomes more cost-effective to use renewable energy sources.
It's in the interests of everyone (except the oil companies) that this happens sooner rather than later. The reason for this is that fossil fuel energy becomes more expensive the more money you spend on it (like diamonds, and for exactly the same reasons), and renewable energy gets cheaper the more money you spend on it (like computers, and for exactly the same reasons). Once all the money we're currently spending on oil goes into research into renewable energy sources rather than research into oil extraction methods, energy will get much cheaper very very quickly, and our transportation, heating and electricity costs will all go way down. Also, we will stop pouring so much money into the pockets of unpleasant middle-eastern regimes.
There are also environmental problems caused by fossil fuels that are not disputed at all, such as the damage caused by oil spills or the pollution caused by coal mining operations. However, we don't yet know what similar environmental problems will be caused by the renewable replacements (perhaps our solar panels will require elements for manufacturing that are also messy to mine, or poisonous chemicals). But given the amount of energy that will be generated by a solar panel (say) over its entire lifetime, it seems unlikely that the environmental problems of using renewable energy will be worse.