As the comment points out, the conundrum with democracy is that it "is well-suited for determining what a majority of the voters in a polity want. It does very little, however, to ensure that what they want is the right thing, or even in their best interests."
Forget global warming. The major barrier to global sustainability is not any environmental constraint, nor is it any economic limitation: no the predominant limitation on sustainability is our inability to successfully grapple with deeply contrasting values in the determination of global governance. Often masked by religious dogma and mis-represented as an ethnic conflict, the differences reflect pronounced and fundamentally distinct world views: ideologies that are different but don't have to be divisive. Sadly, as long as differences exist, someone, somewhere will seek to exploit people's fears and ignorance's as a means to exert power in the name of ideological supremacy.
The irony (or lunacy) of this situation is, of course, that the differing ideologies are at their core and in principle, distinct but not contrasting at all.