Increased temperature stress reduces future yields despite
intensification of irrigation
Abstract
Climate change and variability threatens the sustainability of future
food productions, especially in semi-arid regions where water resources
are limited, and irrigated agriculture is widespread. Increasing
temperatures will exacerbate evaporative losses and increase plant water
needs. Consequently, higher irrigation intensities would be a logical
measure to mitigate climate change impacts in these regions. Using an
ensemble of well-parameterized crop model simulations, we show that this
mitigation measure is oversimplified and that besides water resources
availability, strong temperature increases play a crucial role in crop
developments and resulting plant water needs. Our analysis encompasses
agricultural areas of the Lower Chenab Canal System in Pakistan (15 000
km2), which is part of the Indus River irrigation
system, the largest irrigation system in the world; and covers
economically important crop growing areas (e.g., of cotton, rice and
maize crops). Climate models project an above average increase in
temperature over the study region, and the agro-hydrological and
biophysical crops models respond with a strong decline of up to -24%
(±12%) in future crop productions. Our modeling results further suggest
that evaporative and irrigation demands do not align with increasing
future temperature trends. The resulting decline in crop productions is
consistent among model projections despite an intensification of
irrigation measures and the positive effect of future
CO2 enrichments. Overall, our study emphasizes the role
of elevated temperature stress, its effects on agricultural production
as well as water demand, and its implications for climate change
adaption strategies to mitigate adverse impacts in an intensively
irrigated region.