Yes, the world was a lot hotter in the distant past, but that's because the carbon in the biosphere was gradually sequestered by natural geologic processes, leading to a gradual cooling over hundreds of millions of years. We're now partially undoing that, by pumping and digging the stuff back up and burning it.
If fossil fuels hadn't come along, it's possible that the long-term cooling of the Earth would have been a problem, eventually. Nobody wants another Ice Age. But we've gone waaaay past in the opposite direction now. We really, really don't want to see an "age of the dinosaurs" climate, with its pole-to-pole super-hurricanes, continent sized mega droughts, and other forms of extreme weather that human civilization has zero experience coping with.
This is a fairly predictable consequence of economic stagnation. France is still below its pre-Covid level of GDP per capita, while Germany only caught up. Both countries, and most other countries in Europe, seem to be permanently stuck at a GDP per capita level 20-30 percent below the US.
There are lots of excuses for Europe's lower economic dynamism relative to the US, about how it's a trade-off for improved quality of life (more vacations, etc). But young people benefit disproportionately from dynamism, because they're the ones working their way up. If young people want economic opportunities and the economy doesn't give it to them, you'll see the frustration appearing at the ballot box.