Access to energy is one of the big global issues that has hovered around the fringes of international policy discussions such as the Millennium Development Goals or climate policy, but which has been getting more attention in recent years. In my frequent lectures on climate policy I point out to people that 1.3 billion people worldwide lack any access to electricity and an 2.6 billion more cook with wood, charcoal, tree leaves, crop residues and animal waste (an additional 400 million cook with coal).

Not long after a tsunami washed over Japan's Fukushima nuclear power plants in March 2011, causing a partial meltdown, it appeared to many that humankind's half-century experiment with nuclear power might be in permanent jeopardy. Although nuclear energy provides 15 percent of the world's electricity, all without spewing greenhouse gas emissions, many countries seemed ready to forgo nuclear for deadlier but less viscerally frightening power sources. And sadly, while U.S. political leaders, including those at the just-concluded Democratic National Convention, are quick to trumpet their embrace of natural-gas drilling, the word "nuclear" is scarcely ever mentioned.

U.S. emissions have plummeted 7.7 percent since 2006, thanks to the rapid switch from coal to cheaper and cleaner natural gas. Where did all this cheap gas come from? A concerted, public-private effort dating back to the mid-1970s to cheaply extract gas from shale. There is a clear lesson for those concerned about global warming: seek public-private investments in technological innovation to make clean energy cheap.