Ricky just mentioned a lot of nice programs, and has listed others here and there, and they're all quite worthy of consideration, and just because one can't fix everything at once doesn't mean one shouldn't do what one can, and if AGW's dangers aren't being overstated then it probably makes sense to get moving as quickly as possible even if that means wasting some money. But...
Will you entertain a thought experiment? Think about the world and its energy consumption as it was up until 2007 - let's say from the end of WWII. This is when humankind produced the CO2 that's already causing noticeable warming, and will continue to for some time even if humans disappeared off the face of the planet tomorrow. Now consider
this graph:

"Energy Intensity" is amount used per dollar of GDP and carbon intensity is also a measure of output per dollar of GDP. I interpret this graph to say that output per capita grows so much relative to these intensity measures because standard of living is expected to increase - especially for large masses that currently make do with quite little, as in China and India. So even as we get more efficient as regards the amount of energy needed to sustain a certain standard of living, we're still going to be increasing the total amount of CO2 we put out.
So if what we've done in the past is bad, what we're about to do is worse. As you ponder what might be done about this, keep this graph handy. It's the line that represents CO2 emissions that matters. The other lines are what determine CO2 emission - we're going to have to improve the situation a lot in at least one of them. What would it take to bend that blue line downward with a rate of descent similar to the rate of increase up until now?
I think it's very unlikely that energy intensity can improve much faster than this projection shows. The reason it's gone down from 1990 to today is probably the same reason it's gone down throughout human history: technological improvements. This doesn't mean that we've learned to get more BTUs out of a ton of coal (though we have), but that we're always trying to make, as inexpensively as possible,
everything that's needed by everybody everywhere. Can we simply
decide to increase the rate of technological advance? Of course not. We can make some special efforts in some highly focused areas, but short of a cold fusion breakthrough I doubt we can do more than nudge that line a tiny bit even if Ricky were made dictator of the world.
What about standard of living? (It's not on the graph but is implied by the line for output per capita.) Why should it keep increasing? "Sustainability" is what we need and if we can't reduce our footprint via super-charged technological improvement perhaps we'll just have to accept some stagnation in standard of living: getting along with fewer frivolous consumer goods, a level of medical care no greater than today's, no increase in leisure time or tourism, and so on. I do not think this is likely to happen even if things get really dicey. History provides us with an example of a government that attempted to hold standard of living steady while increasing GDP; they wanted to devote the extra output to different goals. They were in a good position to try - their control of the reins of their nation's economy was strong, they had total control of the media, wide acceptance of the ideology that drove the program, and superb means of coercion. I'm talking about the Soviets. Forget please that I'm a cold warrior; we're talking here only about their economic experiments and experiences. They managed a miraculous increase in heavy industry while holding the production of increasing consumer goods to a minimum - but only for a while. Eventually even they had to satisfy the people's demands for an increasing standard of living. No country on earth today except North Korea can even come close to matching the USSR in terms of ability to pull off that sort of manipulation. The Soviet people eventually became just too jealous of western standards of living; the increasing degree to which we all now share the same communications/media content means that we'll never again see such a long
delay before the masses recognize they're getting the short end of the stick. People everywhere today are demanding a better standard of living. This is true even in the OECD states, which represent just 18% of the world population; imagine the urgency elsewhere.
What about population? We know that as GDP per capita increases birth rates drop, but that's already been included in the models that produced these projections. The population line in the above graph seems to be VERY slowly getting less steep. That's not bad considering that rates were increasing exponentially just off the left side of this graph's time scale. What can we do to reduce growth even more? Can't Mr. Malthus come to our rescue? Yes and no. We already are facing a looming global food crisis even without global warming. What if famine were to kill a billion or so? Two problems: 1) world population is projected to grow by
two billion over the next thirty years, and 2) famine conditions severe enough to kill a billion would motivate the world's peasantry to rapidly
increase rates of procreation.
That leaves just carbon intensity. Why is that line so steady? Can't we wean ourselves off fossil fuels faster? I don't know. I refer you all to
THIS report regarding future demand from the US Energy Information Administration. I suspect the carbon intensity line stays fairly steady because although carbon fuels will make up less of overall fuel use in terms of relative share, total energy consumption will rise even faster. Hypothesis: if it takes X amount of increased energy consumption to bump up from $10,000 per capita to $20,000 per capita, the amount required to move from $20,000 to $30,000 isn't just X but some much larger number.
Conceptually, I have ignored (at least) one very interesting factor. What if people everywhere evolve a different
ethic about sustainability? That could change everything. What I mean by "ethic" in this context is this: when I moved from Boston to Albuquerque I consciously decided to monitor and reduce the amount of water I used, even though it would make absolutely no difference to my personal economy and be an inconvenience. That was a change in ethic. (I'm just giving an example, not holding myself out as a paragon of environmental responsibility; trust me - I ain't one.) What if 80% or more of the world's people started to
really alter all the things that might influence their carbon footprint? For instance, when buying a dwelling one can, for exactly the same amount of money, buy a large place in the suburbs or a smaller one in the city, or a large place with low amenities versus a smaller place with more amenities. In most places, people have an inflated desire for cubic feet of dwelling space. It's reasonable to want more, but the desire has been "artificially" supported by low transport and heating/cooling prices, taxpayer provision of roads and utility hook-ups, and the ad-hoc nature of land development in most places. What if people all over just consciously decided, whenever they might be in the market, to favor smaller structures with more amenities and a more central location? That could have a huge impact on energy use.
I guess it depends on the beliefs you might hold about human nature, or perhaps your own level of idealism. I can picture the world's energy/sustainability ethic, independent of market factors like the
cost of energy, evolving - slowly - much too slowly to matter. But that's just me. Ironically, a major driver of human ethics seems to have a negative effect on this whole thing - at least in the USA. There's a positive correlation between religious belief and AGW disbelief, and if you disbelieve AGW you're certainly not going to change your sustainability ethic on its account. You might think that a belief that a deity with a propensity to be judgmental made the planet would generate a desire to be a good steward of it, but the opposite seems to be true. If you believe in God, you believe (it seems) that
he's the steward, and would never let the planet do something bad to humankind. This seems a bit less than rational given all the real natural disasters and the Noah myth, but rationality and religion needn't exist in the same place at the same time.