Passage I

Earth's climate is affected by the total solar irradi­ance (TSI), the rate at which energy from solar radiation is received by Earth per unit area of the surface. In 2000, sunspot records were used to estimate the TSI at a particu­lar Indian Ocean location over the past 1,100 years. Ocean floor sediment that had been deposited at the location over that same period was analyzed for carbon (C), nitrogen (N), and aluminum (Al). The percents by mass of C, N, and Al, respectively, indicated the intensity of monsoons, ocean productivity, and rate of continental erosion (3 measures of climate) over the period. The results are shown in the figure.