Schmidt is the director of nasa’s Goddard Institute for Space Studies (a.k.a. GISS) a world-class climate-science facility. One day last year, I came to GISS with a far-out proposal. In my work as an astrophysicist, I’d begun researching global warming from an “astrobiological perspective.” That meant asking whether any industrial civilization that rises on any planet will, through their own activity, trigger their own version of a climate shift. I was visiting GISS that day hoping to gain some climate science

insights and, perhaps, collaborators. That’s how I ended up in Gavin’s office.  Just as I was revving up my pitch, Gavin stopped me in my tracks.  “Wait a second,” he said. “How do you know we’re the only time there’s been a civilization on our own planet?” It took me a few seconds to pick my jaw off the floor. I had certainly come into Gavin’s office prepared for eye rolls at the mention of “exo-civilizations.” But the civilizations he was asking about would have existed many millions of years ago. Sitting there, seeing Earth’s vast evolutionary past telescope before my mind’s eye, I felt a kind of temporal vertigo. “Yeah,” I stammered, “Could we tell if there’d been an industrial civilization that deep in time?”  READ MORE