Abstract Since the 1950s, global irrigated areas have expanded dramatically, with complex effects on regional climate worldwide. Although the North China Plain (NCP) is among the most intensively irrigated regions in the world, the effects of irrigation expansion on heat stress over the past multidecadal timescale remain poorly understood. Based on long‐term meteorological records, we identified an enhanced cooling rate of 0.187°C decade −1 due to irrigation expansion during April–June from 1961 to 2005. The cooling effect weakened since 2005 due to improved irrigation efficiency and slowed irrigation expansion. Conversely, irrigation amplified nighttime temperature by 0.117°C decade −1 until 2005 and exacerbated daily moist heat stress by 0.269°C decade −1 after 1980, primarily due to increased humidity at night. Projections to 2050 suggest that irrigation will continue to alleviate heatwaves through cooling with a negligible impact on exacerbating extreme moist heat stress, which remains predominantly driven by climate change.
Yuan et al. (Tue,) studied this question.