First, the good news. Here is an infographic about the U.S. contribution to global warming:
U.S. total energy-related carbon emissions are down 13% since 2007. That's huge. Although the U.S. refused to sign the Kyoto Protocol, we managed about 70% of the emissions reductions mandated by that treaty (which is much better than most of the actual signatories!).
Renewable energy now provides 12.1% of U.S. energy. That is big.
Energy demand has fallen 6.4% since 2007, even though GDP is slightly higher. Hence, energy efficiency is responsible for the reduction in demand. That is good.
Gas is replacing coal. That is good, provided that wellhead methane emissions are not making up the difference.
Bottom line: If the U.S. were the world, the fight against global warming would be going well.
OK, now for the bad news: The U.S. is not the world. Global warming is global. The only thing that matters for the world is global emissions. And global emissions are still going up, thanks to strong increases in emissions in the developing world, notably China.
Figures released this week show skyrocketing Chinese coal use. China now burns almost as much coal as the rest of the world combined:
Meanwhile, Indian coal use is also increasing strongly.
If China and the other developing nations cook the world, the world is cooked, no matter what America or any other country does. China et al. can probably cook the world without our help, because global warming has "threshold effects" (tipping points), and because carbon stays in the air for thousands of years.
Bottom line: We will only save the planet if China (and other developing countries) stop burning so much coal. Any policy action we take to avert global warming will be ineffective unless it accomplishes this task.
What will accomplish this task? What can we do to influence the behavior of China? One thing that might help, on the margin, is to tax the carbon content of imports into the U.S. A second thing would be to tax U.S. exports of coal and other fuels.
But these measures - or any carbon-taxing measures taken only by rich countries - will have limited effects, due to the large size of the developing-world economy, which is set to pass the developed world in size very soon. What else can we do to slow developing-world emissions?
As I see it, there is only one thing we can do: develop renewable technologies that are substantially cheaper than coal, and give these technologies to the developing countries. China in particular is not a very globally responsible country; it will continue to pursue growth, economic size, and geopolitical power at any cost, and that means using the cheapest energy source available. The only way China will stop using coal is if it becomes un-economical to continue using coal.
Thus, the rich world should focus its efforts and money on developing renewable energy cheaper than coal. This mainly means solar; it also means better energy storage and transmission technologies. We should give these technologies away to China and other countries for free; the economic hit we take from doing so will help ease developing-country resentment over the fact that the U.S., Europe, Japan and others got rich by burning fossil fuels in the past.
Developing cheap renewable energy technologies requires research funding from the government. A carbon tax would also help, since it provides a subsidy for private firms to develop their own in-house technologies. However, it will not be possible to give privately owned technologies to China; for these to be rapidly adopted in China in time to save the world, we must rely on natural technology diffusion, or on Chinese espionage.
So, government research is the most important component. We need to increase government funding for solar, for energy storage, and for electricity transmission tech. And then we need to give the fruits of our research for free to the entire world, before it's too late.