[tejohnso]

That's an interesting bit of detail. As you intended, it does not lessen the impact of the statement: "conditions never witnessed by us or our prehistoric relatives". It confirms it, with some additional context.

To me, it seems to make it even more significant. Because as you point out, Homo evolved under ice age conditions over millions of years. Well, here we are about to be thrust into uncharted territory, in an extremely short period of time. With very fragile global interdependencies, an overpopulated planet, and billions of people exposed to the consequences.

[timschmidt]

Right? I would only caution that neither has the ice age been particularly kind to humanity. It seems at least a couple times to have almost gotten us all. There's a genetic bottleneck in genus Homo which seems to date back ~80k years, which aligns suspiciously with the Toba supervolcano eruption. And another around 850k years ago. During each there were likely fewer than 2,000 breeding humans.

Earth has certainly thrived with a warmer climate. No reason we can't too. The problems - for us and other life - stem from the rate of change. Which is easy to see is very very rapid compared to the historical cycles, but still a slow motion trainwreck compared to an asteroid strike, supervolcano, or gamma ray pulse, all of which it seems Earth has experienced. Life and human society will adapt if it has enough time. The quicker the catastrophe the more challenging that is.

I guess what I'm saying is that we're not doing ourselves any favors, but we also shouldn't underestimate mother nature's ability to throw us a curve ball in the 9th inning that makes everything worse. Life has endured an awful lot on this little rock.