Select the correct answer from the list.(1 point)
Between 400,000 years ago until 1950, the levels of carbon dioxide in the atmosphere never exceeded
parts per million. Today, carbon dioxide levels have exceeded
parts per million.
Select the correct answer from the list.(1 point)
Between 400,000 years ago until 1950, the levels of carbon dioxide in the atmosphere never exceeded
300
parts per million. Today, carbon dioxide levels have exceeded
410
parts per million.