基于CMIP6的长江中下游未来水稻高温热害时空变化特征

    Spatiotemporal variation of future heat damage of rice in the Middle and Lower Reaches of the Yangtze River using CMIP6 projections

    • 摘要: 在全球气候变化背景下,高温热害频发已严重影响了中国水稻的产量和品质。长江中下游地区是中国重要的单、双季稻种植区,其产量和种植面积均占全国1/3以上。预估未来不同气候情景下水稻高温热害演变规律有助于合理制定应对气候变化策略,保障中国粮食安全和农业可持续发展。该研究基于观测数据对CMIP6中14种气候模式的日最高气温数据进行偏差校正处理,并进一步结合贝叶斯模型平均(Bayesian model averaging,BMA)算法,评估了长江中下游地区当前和未来单、双季稻关键生育期的危害热积温Ha的时空演变特征。结果表明:1)偏差校正方法可以有效地减少气候模式数据的系统偏差,大多数模式与实测数据的均方误差改善40%以上,BMA集合平均方法能够有效提升气候预估结果的可靠性。2)水稻全生育期的高温热害集中发生在江汉平原、湘中丘陵区以及鄱阳湖平原等地区,并且未来这些地区Ha有着更大幅度的增长。3)随着温度的持续升高,越来越多的地区将暴露在高温热害之下。到21世纪末,在SSP2-4.5情景下,单季稻和双季早稻的Ha相较于历史时期(2001-2014年)增长超过20 ℃•d的区域大于1/3,而在SSP5-8.5情景下,增长超过60 ℃•d的区域更是大于80%。4)单季稻、双季早稻和双季晚稻Ha的最大增长均出现在SSP5-8.5情景的远期,其中全生育期(孕穗—成熟)的最大增长分别为70.8、76.1和14.9 ℃•d。单季稻和双季晚稻的高温热害增加集中在孕穗—乳熟阶段,而双季早稻的高温热害增加集中在抽穗—成熟阶段,在其余生育期,Ha的变化受气候变化的影响较小。研究结果对水稻生产应对气候变化、积极防御高温灾害和保障粮食安全具有重要的科学意义和参考价值。

       

      Abstract: Rice production can be significantly suffered from frequent heat damage with the ongoing climate change in recent years. For instance, the Middle & Lower Reaches of the Yangtze River play an important role in the single and double rice growing areas in China, with a yield and planting area of more than 1/3. Since the beginning of summer in 2022, the middle & lower reaches of the Yangtze River have suffered an unprecedentedly long period of extremely high temperature events, which can inevitably pose adverse effects on the rice growth stages. The estimations on the evolution of heat damage of rice in the future are beneficial to develop reliable strategies for climate change, particularly for national food security and agriculture sustainability. Furthermore, the prediction ability of extreme temperature can be expected to be improved using the latest Coupled Mode Intercomparison Project (CMIP6). In this study, the current and future (2015-2040, 2041-2060, 2061-2080, 2081-2100) was predicted to share the socioeconomic paths (SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5) in the spatiotemporal evolution characteristics of accumulated hot damage temperature for single and double rice. The bias-corrected processing was performed on the daily maximum temperature data from 14 climate models in CMIP6 by the grid observation data in the CN05.1 dataset from 1961 to 2000, and further combined with Bayesian model averaging (BMA). Results show that: 1) The bias correction significantly reduced the systematic bias of climate model data, whereas, the BMA effectively improved the reliability of CMIP6 projections. The CanESM5, IPSL-CM6A-LR, and MIROC6 accounted for a larger proportion, indicating a more accurate simulation of daily maximum temperature, compared with the rest. 2) Single rice and early rice were more susceptible to heat damage than late rice. Heat damage of the whole growth duration of rice was mainly distributed in the Jianghan Plain, the central Hunan hilly area, and the Poyang Lake Plain. There was more significant growth of accumulated hot damage temperature in these areas in the future. 3) Much more areas were exposed to heat damage, as the radiative forcing levels increased. The areas of single and early rice were projected to increase by more than 20℃•d during the 2090s under the SSP2-4.5 scenario, compared with the historical period. There was occupying over 1/3 areas, while the areas increased more than 60℃•d were over 80% under the SSP5-8.5 scenario. 4) The maximum increase of accumulated hot damage temperature in the whole growth period (booting-maturity) for the single, early, and late rice was projected to reach 70.8, 76.1, and 14.9℃•d, respectively during the 2090s. The heat damage increasing in single and late rice was concentrated in the booting to milking maturity, while the heat damage increasing in early rice was concentrated in the flowering to maturity. The change of accumulated hot damage temperature was less affected by climate change in the other growth stages. The finding can provide an important strong reference for rice production to better cope with climate change, particularly against the high-temperature disasters for national food security.

       

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