Question

carbon dioxide concentration at mauna loa observatory
approximately how much did carbon - dioxide increase from 1960 to 2000?
120 ppm
50 ppm
20 ppm
260 ppm
155 ppm

Explanation:

Step1: Read 1960 value

Approx. 320 ppm

Step2: Read 2000 value

Approx. 370 ppm

Step3: Calculate increase

370 - 320 = 50 ppm

Answer:

50 ppm