Memories of terraforming
By the time we realized the damage we had done to our world, it was too late to change our ways. We were going to suffocate. The atmospheric models said we had 200 years—maybe 250 tops—before the air thinned, incapable of shielding us from the sun.
We needed an escape. A planet-scale eject button for civilization.
At this time there were two schools of thought. The first was to look to the stars for refuge. Propulsion technology was getting good. Perhaps good enough to launch us to the next star system. Spectrometers on reconnaissance probes painted pictures of an oasis of lush, habitable planets, a few light-years away. We had two centuries to figure out a way to survive the long journey through the vacuum. As you know now, we did survive, and the rest as they say is history.
But not many remember that a second proposal was also made. There was another planet in our star system at the time, capable of sustaining life. Close to home, but a barren wasteland. A series of controlled thermonuclear reactions could bring about the right conditions for abiogenesis - the origin of life. As to plan, we deployed the bombs and set the planet on fire. But we ran out of time. We were forced to escape to the stars before getting to see the result of our handiwork.
Memory is a pendulum. Swing your mind far back to remember the past and if you let it loose just right, it will swing forward to reveal the future. On a clear night, point your telescope toward our neighbouring star, the one you call Sol. A civilization now exists that reminds me of our carefree past, long before our escape. You’ll find them on the third planet from the sun, one that's teeming with life. We rediscovered them recently. The successful conclusion of a forgotten terraforming project.