I quite like your story about Vinod Khosla of Khosla Ventures, a Silicon Valley venture-capital firm, in your Technology Quarterly (“Betting on Green,” March 12, 2011). Although technology breakthroughs are unlikely to be the answer to climate change, the proliferation of technologies we already have, such as solar and wind energy or electric cars, are even less likely to be the answer. As you quote him saying, he is interested in technologies that have a ninety-percent chance of failure, but would change the infrastructure of society in some radical way in the case they do succeed. “My willingness to fail gives me the ability to succeed,” he explains. “Environmentalists are fiddling while Rome burns,” he argues. His investment portfolio thus reads like an “eco-utopian wish-list,” to use your words: non-polluting nuclear reactors, diesel from microbes, carbon-negative cement, quantum batteries, and a system for extracting methane from coal while it is still underground. Congratulations! Green iconoclasts and financial mavericks like Khosla are our last chance. Walking and gardening are a pretty safe fallback, anyhow.