[Amagi]

Would that be Ice Age prehistoric levels?

[massgopguy]

Sure, get a sample from the top of a volcano.

[Mrs. Don-o]

Mid-Pliocene. The global average temperature (about 3 million years ago) was 2–3 °C higher than today, global sea level 25 m higher and the Northern hemisphere ice sheet was come-and-go --- this was before the glaciation that occurred in the late Pliocene over Greenland.

Nobody ever asks the climate alarmists, "OK, so what is the IDEAL CO² level and earth surface temperature?" As a gardener, my preferences are clear: more and more.

I'm glad my compost pile generates robust amounts of heat and CO². If everybody had a compost pile, maybe I'd reach my target climate: the pretty, pleasant, practical Pliocene.