Global Patterns of Crop Production Losses Associated with Droughts and Floods from 1984 to 2009

Droughts and floods represent an important type of climate extreme that reduces crop production and food security. Although this fact is well known, the global geographic pattern of drought-driven reductions in crop production is poorly characterized. As the incidence of relatively severer droughts and floods is expected to increase under climate change, understanding the vulnerability of crop production to droughts and floods is a key research priority. Here, we estimated the production losses of maize, rice, soy and wheat using empirical relation ships between crop yields, a drought index, and annual precipitation from 1984 to 2009. We find that approximately three-fourths of the global harvested areas — 458 million hectares — experienced drought-induced yield losses over this period, and the cumulative production losses correspond to 114 billion United States dollars. On average, one drought event decreases the agricultural gross domestic production (AGDP) by 1%. Crop production systems display decreased vulnerability, or increased resilience to drought. This change in vulnerability or resilience accompanies technological improvements which are assessed in terms of increases in per capita GDP. Our estimates of drought-induced economic losses in agricultural systems offer a sound basis for subsequent assessments of the costs of adaptation to droughts under climate change.