The leaders of the G-8 and of major developing countries will discuss how to respond to energy security and climate change tomorrow. Their first instinct will likely be to propose new regulations. Yet market forces may already be solving these problems, as high oil prices drive a shift away from the polluting, petroleum-fueled internal combustion engine to cleaner forms of transportation.

That's a change worth cheering, even if oil prices are painful in the meantime. Oil is the United States' principal transportation fuel,...