Passage III
Greenhouse gases such as methane (CH4) warm Earth's climate. Figure 1 shows the concentration of CH4 in Earth's atmosphere and the solar radiation intensity at Earth's surface for tropical Europe and Asia over the past 250,000 years. As the figure shows, the CH4 concentration and the solar radiation intensity have increased and decreased at the same times over most of this period. Figure 2 shows the same types of data for the same region over the past 11,000 years. This figure is consistent with the hypothesis that the greenhouse gases from human activities may have begun warming Earth's climate thousands of years earlier than once thought.
17. Based on Figure 1, the average solar radiation intensity over the past 250,000 years was closest to which of the following?
Your Answer is
Correct Answer is C
Explanation
Look at the solar radiation curve in figure 1, which is about 480 (the vertical axis on the left), so the average value should be close to 480