the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Spatiotemporal variation of growth-stage specific compound climate extremes for rice in South China: Evidence from concurrent and consecutive compound events
Abstract. There is increasing concern regarding the impact of compound agroclimatic extreme events on crop yield, particularly in the context of projected increases in their frequency and intensity due to climate change. While previous studies have generally focused on compound hot and dry events in maize and wheat using growing-season relative thresholds, the time-variant physiological sensitivity of crops to climate extremes has not been sufficiently considered. We determined the spatiotemporal variations of compound climate extremes (CEs) for single- and late-rice in southern China during 1980–2014 and their underlying drivers using growth-stage specific physiological thresholds. Specifically, we carefully distinguished between concurrent compound events (CCEs) and consecutive compound events (CSEs). Our results indicated an increasing trend of compound hot-dry events for single-rice, but a decreasing trend of compound chilling-rainy events for late-rice. Spatially, the hotspots of compound hot-dry events for single-rice shifted from the lower Yangtze River Basin to its upper stream, and were dominated by the spatial differences in phenology rather than the occurrence of extreme events. The hotspots of compound chilling-rainy events for late-rice remained concentrated near the northwest edges of late-rice growing areas, indicating the limitation of thermal conditions. The occurrence and duration of CCEs was closely related to local temperature-moisture coupling (negative correlation). A path analysis suggested that temperature was the dominant factor influencing the changes in compound hot-dry events for single-rice. For the changes in compound chilling-rainy events for late-rice, the effect of temperature was only slightly larger than that of moisture. Our study has improved the understanding of compound climate extremes in China’s rice production system, and the results provide important information for risk management and adaptation strategies under climate change.
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Status: open (until 20 Jul 2024)
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RC1: 'Comment on esd-2024-8', Anonymous Referee #1, 30 May 2024
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This paper investigates the combined climate extremes relevant to rice production in China. The authors analyze concurrent and consecutive compound events relevant for single- and late-rice during 1980–2014, using specific known thresholds. Examining both concurrent and consecutive extremes provides a more comprehensive picture of potential stress on rice crops. However, the manuscript would benefit from addressing some fundamental points and key concerns:
1- Sample Size Concerns: First concern is regarding the sample size of stations, highlighting the potential lack of representativeness for the entire region. Given the substantial spatial heterogeneity of soil moisture, the limited number of stations may not fully capture the diverse conditions across China.
2- Missing Yield Impact Assessment: While the paper mentions rice yield as motivation, it lacks a direct evaluation of how these compound events affect production quantities. It is necessary to incorporate an analysis of yield data to directly assess the impact of compound events on rice production. The paper's association with rice is primarily through growing season definitions, yet there is a noticeable absence of yield estimation. The justification for focusing on rice should be more explicit, particularly considering the absence of yield data.
3- Growing Season Definition Clarity: Specifying whether the growing season definition has fixed planting and harvest dates or adapts based on actual planting times is crucial. Sensitivity analysis to choice of dates is necessary to understand how changes in the selection of growing season start and end could influence the results.
4- Intensity Metric Considerations: The current focus on number of extreme days based on thresholds might overlook the intensity of extreme events. Analyzing the magnitude of temperature or drought deviations could provide deeper insights. The metrics employed in the study center on frequency and the number of days above a threshold but fail to consider the intensity of compound events. It is important to consider the intensity, as a single day with a temperature 10°C above the threshold could have more substantial implications for agriculture than ten days with only 0.5°C above the threshold.
5- Practical Implications and Value Added: Explicitly discussing the practical applications of the research and its contribution to existing knowledge would enhance the paper's value for the scientific community.
Citation: https://doi.org/10.5194/esd-2024-8-RC1
Data sets
A daily 0.25° × 0.25° hydrologically based land surface flux dataset for conterminous China, 1961–2017 Yue Miao and Aihui Wang https://doi.org/10.1016/j.jhydrol.2020.125413
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