There's a reason we use fossil fuels -- they're very cost-effective. Banning (or drastically restricting) them would economically cripple the developed world and devastate the poor countries. Is it moral to harm billions of people now, just in case it makes a difference, later?
At the same time, it would be stupid not to learn from our past mistakes. Regardless of whether global warming is the fault of us humans or not, toxic emissions harm our planet and us in other ways: acid rain, diseases etc. So focusing on renewable energy sources even in developing countries seems more "moral" to me, because it takes into consideration sustainability--after all, fossil fuels are running out.
Not planning ahead is stupid, just like insisting on "staying the course" when it turns out you've screwed up
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