Why was the concern over global cooling replaced with a concern over global warming?

The concern shifted as temperature records showed a sustained rise in global surface temperatures from the 1970s into the 1990s. That evidence brought global warming to the forefront, making choice B, “Steady surface temperature increases were noted between the 1970’s and 90’s,” the best answer. Air pollution was already a concern earlier, and ocean acidification was not the reason for the shift.

AI-written and checked against the verified answer.