The challenge of climate change is aptly called “civilizational.” We live in a world built by fossil fuel energy. The costs of fossil fuels are well documented — not just climate change but also millions of deaths per year from air pollution — but the benefits of fossil fuel–powered modernity are too often ignored. Fossil fuels have powered electrification, industrial mass production, rapid long distance transport, virtually labor-less agriculture, and provided the industrial heat to forge a more-than-50-percent urban world built of steel and cement.

The level of energy needed to replicate this bounty is hard to imagine. Fossil fuels are high in what energy experts call “energy density”: the amount of energy contained per unit of volume or mass. The historian Alfred Crosby explained that this is because these fuels represent “fossilized sunshine,” or the millions of years of solar energy concentrated into condensed plant matter. According to Crosby, a mere gallon of gasoline would need the equivalent of ninety tons of plant matter or forty acres of grain to produce the equivalent energy.

We still live on a planet where roughly 80 percent of the world’s energy is powered by fossil fuel. This means that, in contrast to what many climate activists might suggest, the transition away from fossil fuels is neither technically simple nor just a matter of political will. It is incredibly difficult and requires a serious technical analysis of potential alternatives.