The Indian summer monsoon rainfall (ISMR) has remained remarkably stable during the last 140 years. The ISMR has varied between 70% and 120% of the long-term average of about 85 cm. Monsoon seasons with ISMR of less than 90% of the average are considered to be droughts, whereas those with more than 110% rainfall are considered as excess rainfall seasons. Although the variation is not large (Figure 1), it has a substantive impact on our agriculture and gross domestic product (GDP).

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