Apart from having a national Open-Your-Freezer day to cool things down [joke], what realistically can be done? We can't impound all fossil-fuel burning vehicles. We can't shut down the coal electric plants. We can't stop China and other developing regions from buying hundreds of millions of cars and refrigerators and electronics.
The random environmentally conscious person may trade in her Explorer or Accord for a Toyota Prius and feel nice and self-righteous about it, but has she truly helped the environment? The amount of energy expended to manufacture that Prius, and to dispose of that older vehicle (or merely to pass it on to another driver who'll use it for ten more years) far exceeds the trivial few barrels of oil per year that it conserves. Long term, sure, if we were all driving electric hybrids or pure electrics, we'd be generally reducing atmospheric carbon content, assuming the electric plants weren't making up for it by burning more coal and oil. (If we all switched to bicycles, an argument could be made, but of course our economy would all but shut down.)
So what can we do other than wring our hands and worry fruitlessly? Well for one thing, we can at least maximize our efficiency which in the U.S. is pretty easy because we're so wasteful. An engineer famously observed that California's rolling blackouts a few summers ago could have been prevented had they merely painted white the roofs of all public buildings in that state.
Technology is gradually solving these problems, without particular government intervention and sometimes despite such intervention. For example, solar panels are coming down in price, led by the increasingly dominant Chinese manufacturers. You know it's happening because American panel manufacturers are demanding an anti-dumping injunction. At the same time, a variety of new solar-to-electric technologies are in the pipeline, ranging from spray-on applications to bendable and foldable sheets, to bandwidth-specific crystals, to 3-D blocks that are more efficient per area, and on and on. DARPA is experimenting with 50% efficiency solar cells.
Ultimately, most homes and commercial buildings can and should have some form of solar on the roof; as costs of building these features into new construction or retrofitting them to existing structures fall, it will make enough economic sense that it will happen all by itself, and peak demand for electricity will fall even as demand for storage batteries and fuel cells and solar panel equipment skyrockets (now you know where to invest your money).
The other big trend is the availability of cheap natural gas from fracking, which is driving the construction of new gas electric plants and gas-heating in homes. Fuel oil is expensive; gas is dirt cheap. The simple economics will force a mass conversion to this relatively clean and cheap power source.
Ultimately, we will diversify away from reliance mostly on fossil fuels to a mixture of about half fossil and half clean. The impact this will have on the atmosphere is not fully understood, however, and probably would take decades to be observed. Nonetheless, in the latter half of the 21st Century we can expect to have cleaner skies, at least. If we can actively foster reforestation across the Americas and Asia, and if we can somehow reduce the pollution of the oceans which is killing the plankton that furnish most of our oxygen, we may long term reverse the CO2 increase and perhaps eventually this will drive down temperatures.
Or, maybe these climatic changes have little to do with human activity and nature will simply take its course, regardless of what we do. But at least we should, in my opinion, un-do some of the obvious damage we're causing and optimize conditions for a healthier planet.
My other pet solution is to push a trillion ton block of ice out of Saturn's orbit and dump it onto the North Pole, which might buy us a couple extra decades at least.
