FIGURE 3. Relationship between the July–October mean values of western Amazonian rainfall and the ANSG index.

Observations for the period 1901–2002 are plotted with black crosses^{17, 20}. Model output from the HadCM3LC GCM run with aerosols⁸ is plotted with black diamonds for the historical period (1901–2002) and with green diamonds for the simulation of the twenty-first century (2003–2100). The black lines are the best-fit straight lines to the observations (1950–1999; solid) and the twentieth-century simulation (1900–1999; dashed). The green line is the best quadratic fit to the entire GCM simulation (1860–2099). The large black cross shows the mean and standard deviation of the observations, and the red bar shows the range of estimated values for the 2005 Amazon drought.