Irrigation and Climate Change: Long-run Adaptation and its Externalities

Irrigated agriculture is the largest user of water worldwide, covering about 20% of global cropland and generating over 40% of food production. It is also a key potential adaptation to climate change. This paper examines how much of today’s global irrigation footprint can be attributed to climate change over the last 50 years. Using variation in local climate, Taylor shows that increasingly severe drought conditions are associated with irrigation expansion in areas with groundwater potential, both globally and in the United States. GRACE satellite data indicate that this expansion contributes to aquifer stress and higher soil salinity, highlighting negative externalities of climate adaptation and raising concerns for future food security.