If we switch to carbon-free fuels quickly, our greenhouse gas emissions will keep the world slightly warmer than today for as long as 100,000 years. As unsettling as that may be, the alternative is even more severe. If we burn all remaining fossil fuels, including our huge coal reserves, the warming will be five to ten times more extreme and last five to ten times longer.
In short, we’ve become a shockingly powerful force of nature. I liken this revelation to the first NASA photos of Earth, from which we learned that we ride a delicate blue bubble through deep space. This equally transformative view of our place in deep time shows that we are also incredibly important. We’re now so numerous and our technology so powerful that the effects of our collective actions in coming decades will echo on down through the ages.