Saul Griffith is an engineer, inventor, serial entrepreneur, and visionary thinker currently working at Makani Power, a renewable energy company he co-founded in San Francisco.

In this FORA.tv presentation given earlier this year at the Long Now Foundation, Griffith examines the numerical reality of the fight against climate change. Drawing from a personal assessment of his own energy needs, Griffith argues that we not only need to switch to alternative energies, we also need to drastically reduce their consumption in order to prevent a global catastrophe.

In this clip, Griffith lays out in hard numbers the need for a massive increase in "green" energy, and proposes how it can be achieved. The full program is recommended viewing and available on the FORA.tv website.