Attribution of observed changes in extreme temperatures to anthropogenic forcing using CMIP6 models
Attribution of observed changes in extreme temperatures to anthropogenic forcing using CMIP6 models
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DOI：
10.1016/j.wace.2023.100548
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发表时间：
2023-03
影响因子：
8
通讯作者：
Mastawesha Misganaw Engdaw;A. Steiner;G. Hegerl;A. Ballinger
中科院分区：
文献类型：
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作者：
Mastawesha Misganaw Engdaw;A. Steiner;G. Hegerl;A. Ballinger
近年来，全球变暖明显影响了极端事件的发生。在这里，我们使用基于百分位数的指数评估极端温度频率的变化及其原因。极端寒冷的定义是温度低于每日最低温度 (TN10) 和最高温度 (TX10) 的 10%，而极端炎热的温度超过每日最低温度 (TN90) 和最高温度 (TX90) 的 90%。我们分析了伯克利地球表面温度（BEST）在过去四十年（1981-2020）两个延长季节（北半球夏季 4 月至 9 月（AMJJAS）和北半球冬季 10 月至 3 月（ONDJFM））观测到的变化，并使用多个再分析数据集评估结果。对于原因归因，我们使用 CMIP6 气候模型模拟，分析纯自然强迫和纯人为强迫。我们使用一种归因方法来解释气候模型在响应幅度和模式方面的不确定性。观测结果显示冷极端温度和热极端温度都存在可检测到的变化。过去几十年来，所有地区和两个季节的极端炎热天气都有所增加，而极端寒冷天气则有所减少。我们的归因分析表明，人为强迫是可以可靠检测到的，并且是所有区域所有指数观察到的变化的主要驱动因素，在所有数据集中都是一致的。自然强迫的贡献很小，仅在少数地区可检测到，主要是 ONDJFM 的白天极端寒冷。在全球范围内，人为强迫导致 TN90 平均每十年增加 3.4 天，TX90 平均每十年增加 2.7 天。从区域来看，人为贡献导致TN10每十年减少2-4.7天，TX10每十年减少1.5-3.6天，而导致TN90每十年增加2.2-4.8天，TX90每十年增加2-3.3天。 ONDJFM 中仅人为造成的变暖略低于 AMJJAS。
Global warming has clearly affected the occurrence of extreme events in recent years. Here, we assess changes in the frequency of temperature extremes and their causes, using percentile-based indices. Cold extremes are defined as temperatures below the 10th percentile of daily minimum (TN10) and maximum (TX10) temperatures while hot extremes exceed the 90th percentile of daily minimum (TN90) and maximum (TX90) temperatures. We analyze Berkeley Earth Surface Temperature (BEST) for observed changes in the last four decades 1981-2020, for two extended seasons, boreal summer April–September (AMJJAS) and boreal winter October–March (ONDJFM), and evaluate results using several reanalysis data sets. For the attribution of causes we use CMIP6 climate model simulations, analyzing natural-only and anthropogenic-only forcings. We use an attribution method that accounts for climate modeling uncertainty in both amplitude and pattern of responses.The observations show detectable changes in both cold and hot extreme temperatures. Hot extremes have increased in all regions and in both seasons while cold extremes have decreased over the past decades. Our attribution analysis revealed anthropogenic forcings are robustly detectable and the main drivers of observed changes in all indices for all regions, consistently in all data sets. Contributions from natural forcings are found small and detectable only in a few regions mainly for daytime cold extremes in ONDJFM. Anthropogenic forcing contributed to an increase of 3.4 days per decade in TN90 and of 2.7 days per decade in TX90, on average, at the global scale. Regionally, the anthropogenic contribution caused a range of decrease of 2–4.7 days per decade in TN10, 1.5–3.6 days per decade in TX10 while it caused an increase of 2.2–4.8 days per decade for TN90 and 2–3.3 days per decade in TX90. Anthropogenic-only warming in ONDJFM is slightly less than in AMJJAS.