The challenge of the century is the imperative to move to 100% renewable energy. This must happen in the next three or four decades as we approach three critical limits. First, the finite reserves of non-renewable's (fossil fuels and uranium) will begin to decline. Second, increasing demand for energy. Third, increasingly destructive impacts from global warming. Combined these threats pose the greatest challenge ever faced by society. Our children's future depends on our rapid move to 100% renewable energy everywhere.

Economically, socially and scientifically the only way to avoid disaster is a global switch to 100% renewable energy. Only this can realistically address the challenge. No other option can be implemented as fast. Only with "renewable" energy is the reserve and growing demand problem resolved, and yes sufficient free supply is available, with more than 1000 times more renewable energy reaching earth from the sun (and available equitably and locally everywhere in the form of solar, thermal, wind, geothermal, and wind). By rapidly reducing and eventually eliminating the emission of carbon, global warming can be averted with many economic, social and political benefits.