If you could solve one global problem tomorrow what would you solve?

I would solve fusion - you see, unlimited clean energy for the world solves virtually all the other problems people have mentioned. All countries are energy independent which quells wars for resources. Unlimited resources can be created or extracted that are prohibitively expensive today. Desalination, hunger and climate change solutions can be implemented at scale. As for research, we can radically scale up the amount of compute we have access to by over a hundred orders of magnitude, this and AI allow us to anticipate and solve upcoming and existing challenges such as disease, medicines and innovation bottlenecks