Sapoty Brook, Mullumbimby.
The recent discovery of Aboriginal coastal occupation near Darwin 65,000 years ago fits well with the Lake Toba supervolcano 71,000 years ago. That was the biggest volcano in the last several hundred thousand years.
That volcano blew about 800 cubic kilometers of earth, ash, and anti-greenhouse sulphurous gas into the stratosphere causing a 6 year global volcanic winter freeze. This flipped the global climate into a 1000 year chill with temperatures about 10 degrees below normal. According to genetic forensics this reduced the global human population to less than 10,000 people, euphemistically called a genetic bottleneck.
Sounds like just the thing to stop climate change, doesn’t it.
The consequent catastrophic global dieback of frozen forests opened up paths for immigration out of Africa by some of the smart survivors… no offshore immigration detention centers to worry about then, but plenty of incentive to move fast across the entire Eurasian land mass in every direction in desperate search of food, sunshine, and neanderthals to backpack with.
So now we watch the sky, dreading a new genetic bottleneck, of our own making, approaching. We find ourselves contemplating migration to the Moon and Mars. As they wrote on the cave wall, “prehistory always repeats”, so quick, lets open an off-world immigration detention center for fossil fuel company executives.