Mark Garlick/Science Photo Library/Alamy
There is something strange about Earth. Billions of years ago, a process that we have never seen anywhere else began here. It completely reshaped the planet’s surface and the carbon cycle, sculpted new landscapes, and kept our home warm and livable for billions of years.
This process is plate tectonics, in which the Earth is constantly absorbing and reforming the layers of its rocky outer shell. It is believed to be inextricably linked to livability and perhaps a prerequisite for life. Without it, our lakes and rivers could freeze or evaporate, our oceans would be starved of nutrients, and Earth’s climate would likely have drifted into unlivable territory long ago. Life was going to be a rough ride.
At least that’s the idea. But it’s hard to know if plate tectonics is really central to Earth’s green ecology, because we have nothing to compare it to. We know of no other planet that exhibits plate tectonics: of the four rocky planets in our solar system, Earth is the only one that recycles its crust in this way, and we’ve seen no definitive signs of it outside our solar system either.
Until recently, that was more or less the end of the story. But now, with the help of The James Webb Space Telescope (JWST), scientists are beginning to explore the geology of rocky worlds beyond our solar system. Finding one with plate tectonics will be a huge ask. But if we succeed, it could be the key…
