We're going to use a generous definition of "fixed" here that is closer to "stops getting worse."

Criteria for considering the problem "fixed"

Global warming:

• over a period of five years, atmospheric levels of CO2 and methane stagnate or decrease

• average global temperature remains stagnant or decreases over a period of five years

Micro plastics

• 10 or more rigorous studies indicate that the amount of microplastics in human bodies and the ocean have decreased or remained static for a period of five years

• There is no major scientific dispute of the verification of the above findings (as defined by myself)