Growth stage-dependent extreme temperature stresses on crop yield

Climate change has increased the frequency and intensity of extreme temperature events, posing growing threats to food security. This study develops a phenology-based framework to assess their impact on wheat and maize yields in Henan Province, China. Leveraging high-resolution phenological and meteorological data, crop growth is segmented into three stages, with stage-specific thermal stress indices constructed for warm days, warm nights, cold days, and cold nights. Fixed-effect climate econometric models are specified to estimate the marginal yield impacts of extreme temperatures over 2000–2020, and future losses are projected under three Shared Socioeconomic Pathways. Wheat is most vulnerable to cold stress during transitional and reproductive stages, while maize is most affected during late development. Wheat suffers greater cumulative losses due to higher exposure and yield base. Over 2000–2020, extreme temperatures caused an average annual grain yield loss of approximately 0.82 million tons (about 3 % of total production). Future warming is projected to shift crop vulnerability from acute cold to chronic heat stress, with significant losses expected even under low-emission pathways. Crop- and stage-specific vulnerabilities to extreme temperatures differ between wheat and maize, highlighting the importance of targeted risk assessment. These findings highlight the need for crop- and stage-specific adaptation strategies to strengthen regional food security. • A phenology-based framework quantifies crop yield losses from extreme temperatures. • Wheat and maize exhibit stage-specific sensitivities to thermal stress events. • Future yield risks are shifting from cold-induced losses to chronic heat exposure. • Even under low-emission scenarios (SSP1-2.6), significant yield losses are expected. • Adaptation strategies should be crop-specific and phenology-targeted to ensure food security.