After reading the paragraph below, answer the questions that follow.

The graph shows records of temperature (light gray line) and CO
2 (dark gray line) over the past 1,000 years. CO
2 is recorded in parts per million (ppm).
Currently, atmospheric CO
2 levels are approximately 400 ppm. The annual mean growth rate in CO
2 is about 2 ppm/year. Assuming this trend continues, what would you predict the CO
2 level to be in 100 years?
◦ 200 ppm
◦ 1,000 ppm
◦ 600 ppm
◦ 100 ppm