100 Million Years AD

Abstract

A storyteller arrives, one hundred million years from now, to tell the tale of the human species. It is an interval that will add a couple of per cent to the age of the Earth and a little under one per cent to the age of the Universe. Geologically, it is the near future. Cosmologically, we are almost there. There will be an Earth, that which we now call our own. On it there will be, very probably but not quite certainly, oceans of liquid water, an oxygen-rich atmosphere, and an abundance of complex, multicellular life. The Earth is abnormal, and that will draw any interstellar travellers in. The spaceship’s sensors—a simple spectroscope will suffice here—will immediately register the highly reactive surface chemistry that is out of any sort of normal equilibrium. An oxygen-rich atmosphere is not normal. Even from a distance of many millions of miles, this will be a planet that is obviously alive. Closer up, the living skin on the planet, regulator of that planetary surface chemistry, can begin to be glimpsed, as the green wavelengths that mingle with the blue of the oceans of liquid water and the brown of the rock surfaces. Our future visitors would not yet be aware of chlorophyll, but that unexpected signal shining through in the light spectrum would certainly arouse their curiosity. Rock, oceans . . . and green stuff. The geography of the Earth, to our own human and contemporary eyes, would look oddly familiar, but distorted: as though remodelled by Salvador Dali. Familiar landmasses will be displaced. But where to? Unfortunately, we cannot predict where the Earth’s continents will be in one hundred million years’ time. Will the Atlantic Ocean continue to widen, and the Pacific Ocean shrink? Will the East African Rift expand into an ocean? Will the continents aggregate into super-continents, as has happened in the past? Long-term tectonic forecasts, like long-range weather forecasts, are subject to such uncertainties that detailed prediction becomes useless; there are simply too many possible alternative futures. Our planet’s physiography will simply be different, one hundred million years from now, though with elements we would find partly familiar, rearranged as though by the hand of some gigantic and playful child.