What would happen if the richest 10% reduced their CO2 emissions to the EU average (which BTW is a nice standard of living).

Answer, there would be a 35% decrease in global CO2 emissions.

So, all would be fixed, if we could limit the excesses of the top 10%.

@MarkHoltom "all would be fixed"= nothing would be fixed.
If you have a burning house like we have a planet in a climate crises fueled by burning fossil stuff, cutting down global emissions by 32% is like putting out 35% of the flames.
The house is still burning. Even if we put out all flames nothing is fixed yet nor is it a complete solution to the problem in the first place.

See "Brighter" by Adam Dorr, RethinkX for further investigation:
https://rethinkdisruption.com/brighter-1-the-future-of-the-environment/

Brighter transcript: Episode 1 - The future of the environment is brighter than you think - Rethink Disruption

This is a transcript of 'Episode 1 - The future of the environment is brighter than you think’ by Adam Dorr. The entire series is available on YouTube. The

Rethink Disruption