A second key to deep decarbonization brings up an inconvenient truth for the traditional Green movement: nuclear power is the world’s most abundant and scalable carbon-free energy source.76 Although renewable energy sources, particularly solar and wind, have become drastically cheaper, and their share of the world’s energy has more than tripled in the past five years, that share is still a paltry 1.5 percent, and there are limits on how high it can go.
