Scientists like to low-ball their estimates.  The now-famous IPCC scenarios for the effects of climate change are already known to be woefully, unrealistically conservative (Freeman Dyson's recent opinions notwithstanding). Arctic changes expected 20 years from now are happening now, and in North America the beginning of spring has already been pushed back by two weeks, which is enough to play havoc with the fertility cycle of many migratory birds (among other consequences).  The worst-case scenarios used in public debate ignore some extremely worrisome factors, such as the possible release of oceanic methane from clathrates. If we're going to deal with this problem, we have to do it now, as in, within the term of your next government.

Science fiction writers, on the other hand, are generally optimistic--if not about the fate of humanity, then at least about the progress of technology.  The ultimate in technological optimism is the idea of the technological singularity, which posits that technological advance is exponential and, driven by progress in artificial intelligence, will soon hit the vertical slope of the curve.

Maybe.  In fact, let's assume that this mythology is true and, within about 25 years, computers will exceed human intelligence and rapidly bootstrap themselves to godlike status.  At that point, they will aid us (or run roughshod over us) to transform the Earth into a paradise. 

Here's the problem:  25 years is too late.  The newest business-as-usual climate scenarios look increasingly dire.  If we haven't solved our problems within the next decade, even these theoretical godlike AIs aren't going to be able to help us.  Thermodynamics is thermodynamics, and no amount of godlike thinking can reverse the irreversible. 

If there's to be a miraculous transformation of human civilization, it has to be accomplished by us, right now, and without the aid of any miracle technologies.  (That said, technology is a large part of the answer--and game-changing breakthroughs are possible--but until proven otherwise it's existing systems such as wind power that we have to assume we'll be using.)  The technological singularity may be real, but who cares?  By the time it happens, we'll have won or lost our grand battle with fate.

Therefore, here's a rare piece of advice for my fellow science fiction writers:  forget the singularity.  Even if it's real, it's irrelevant.  The decisive moment in history is now, before it occurs.  Seize that, write about that. 

All else is distraction.