That humans are actually the rational beings many claim themselves to be, rather than animals that makes decisions based on emotion and then rationalise why they made the decision.
I feel it would solve all the problems other commenters have mentioned.
I like the direction of this thought. I’ve imagined the same, until I remembered that before fossil fuels, humans used whale oil for lamps, lubricants, soaps, etc, and cut down trees for heat.
This is one of those “be careful what you wish for” scenarios. 8 billion people burning trees for heat and killing whales for lighting creates a whole new hellscape.
Ideally, global warming, but it would be fair to view that as pointless when dissipating the extra CO2 doesn't necessarily return the trees and the problem would degrade again in a couple hundred years. You'd have to introduce a new fuel source that is sought after, clean, and eternal. Which would be two wishes.
So you have to define it as both of your options, since the loss of either worsens the other. Turn the whole environment back to where it was in the 1200s, overrun the streets with bears, see if I care. It'll give 'em something to do. Especially the Amazonian avocado farmers.