You're right that global warming is an existential threat. And right now the power grid is contributing to it.

At the same time, we're seeing constant innovations in solar power and battery technology, while the cost of both are going down. Solar is now the cheapest source of energy per unit. There is enough energy from the sun to cover multiples of all current energy use by humans.

AI models started out as extremely energy intensive, but are becoming increasingly more efficient. You can now run models on your phone with abilities which previously required a server running dedicated graphics cards.

You're also right that we shouldn't outsource critical thinking. Still to say AI has "all the worst use cases" is wrong. Yes, it has plenty of bad use cases, by many great ones. I use it in my day to day work to save time.

Something like a law banning the use of AI will never pass, and if it did, other countries wouldn't also pass it. A country which uses AI will outperform one that does not (economically, although probably militarily as well). In that scenario, leaving AI capability in the hands of private enterprise makes us subject to the whims of rich elites. For an analog see the case of Elon Musk turning Starlink on/off in Ukraine. Which again is why I do think there's value in open source AI, and more specifically AI only available to democratically controlled entities - nation states but also things like worker cooperatives to compete with corporations.