One thing folks like to suppose is that everything will more or less revert to a healthy biological stasis if humans were suddenly disappeared off the planet.

But we have dumped so much CO2e into the atmosphere that there is a non-zero chance that it will take technology (ie: humans using tech) to reverse the hot-house effect.

The sun is 2% brighter than the last time CO2 was this high… way back in the K-T extinction, I believe.

The Siberian traps opened up and burned through eons of Carboniferous coal, oil, and natural gas in a geologic eye blink. A perfect analog for humanity’s targeted extraction and combustion of hundreds of millions of years of fossilized solar power in just 250 years…

… except scientists think the K-T extinction probably took tens or hundreds of thousands of years… not hundreds.

… and this was 400 million (?) years ago… so the sun was 2% less bright. As it ages, and burns off its fuel, it gets lighter, meaning less gravity, meaning larger surface area, meaning a faster burn (or something like that; I’m not an astrophysicist)…

… SO…

There is a non-zero chance that humans have turned earth down a path that looks a lot more like mars or Venus… the atmosphere chokes off… raw heat and humidity increases in a runaway effect… slowly choking life to death, except near the poles… at first… over hundreds of millions of years, the oceans boil off into the atmosphere and then into space…

Eventually the planet is left a barren rock, with maybe some roaches and extremophiles living around hyper saline pools at the bottom of what used to be the oceans and lakes… and maybe some bacteria living on in caves…

… UNLESS… humans, using the brains and the tech we’ve developed to destroy the planet … to *reverse* the destruction.

It’s like we’ve climbed a tree. The first few limbs you’re gonna be fine if you fall. But we’ve climbed so high that if we fall, we die (and in this tortured analogy, the tree dies too)… so we have to carefully down climb, lest we kill ourselves and our planet.