To be fair switching to nuclear was an option in the 70s-90s. Obviously it would have a been a bit more expensive but it would have slowed down climate change by 10-20 years.

On average, maybe yes. But in the rich world we also used a huge chunk of fossil fuel for relatively small marginal gains in quality of life (adding a fifth weekend shopping trip per year, buying a superyacht), and sometimes worsening life expectancy (driving too much, eating too much beef).

We could have just built nuclear power plants. Invested into the technology, built breeder reactors and all that. We wouldn't have had to sacrifice anything, except of course for the astronomical profits of oil and gas companies.

And sure this wouldn't have solved the entire problem, electricity generation only accounts for like 40-50% of CO2 emissions or so? But it would have made a huge difference, and allowed us to focus entirely on the other half of the problem.

And it's not "slight warming". 20,000 years ago the global average temperature was about 3 degrees celsius lower than the reference point. That was the last ice age. Today we are 1.5 degrees above the reference point, 4,5 above the ice age. In a few decades we'll be at 3 degrees above reference, 6 degrees above ice age.

The transition from ice age (-3) to the temperate climate that allowed humanity to thrive, took place over about 12,000 years. The transition from reference to +3 is taking place over about a century. And we won't stop at +3, it'll keep going. Already at 1.5 it's having huge profound effects.

Look at this chart, this should help you understand the severity of the situation. https://www.dpg-physik.de/veroeffentlichungen/publikationen/...

This is literally the end of the world as we know it. It's already well on its way. We are already seeing widespread crop failures, water scarcity, blistering heat waves, extreme weather etc. It will get much worse, this is just the beginning.