高温背景下干湿复合气候异常时空分异与演变趋势

Spatiotemporal Differentiation and Evolutionary Trends of Compound Dry-Wet Climate Anomalies against High-temperature Background

摘要:

在全球变暖背景下,气候异常正从单一维度的独立影响向多维度的复合压力演变,然而现有研究多聚焦于多种异常在同一时段的叠加（即同期复合）,而忽视了气候异常在时间维度上的连续累积效应（即连续复合）。基于1960—2019年多源观测与再分析数据,本研究构建了以高温为先导条件的分析框架,系统评估了全球陆地同期与连续复合气候异常（高温-干旱/湿润）的时空演变规律。研究结果表明,连续复合风险与同期复合风险表现出显著的空间重叠特征,即高频同期复合热点区往往也是连续复合发生热点区。全球超过90%陆地已遭受复合气候异常的影响,主导模态呈显著的纬度带双极格局,即北半球高纬度地区由暖湿复合主导,而热带及南半球地区由暖干复合主导。过去60年间复合气候异常总频数增加5~7倍,且演变趋势表现出显著的路径依赖特征,即同期暖干主导区呈干旱强化路径,而暖湿主导区呈湿润强化路径。本研究揭示了气候变化正表现为更具累积效应的长周期复合模式,强调了将连续复合气候异常纳入全球气候风险评估及适应性管理的紧迫性。

Abstract:

Under the background of global warming, climate anomalies are evolving from single-dimensional independent impacts toward multi-dimensional compound pressures. However, existing studies mostly focus on the superposition of multiple anomalies within the same period (i.e., concurrent compounding), while neglecting the continuous cumulative effect of climate anomalies along the temporal dimension (i.e., consecutive compounding). Based on multi-source observations and reanalysis data from 1960 to 2019, an analytical framework with high temperature as the preceding condition was constructed, and the spatiotemporal evolution of global concurrent and consecutive compound climate anomalies (high temperature-drought/wetness) over land was systematically evaluated. The results showed that consecutive compound risk and concurrent compound risk exhibited significant spatial overlap: hotspots of high-frequency concurrent compounds were often also hotspots of consecutive compounds. More than 90% of global land had been affected by compound climate anomalies. The dominant mode presented a pronounced bipolar pattern along latitude bands, with warm-wet compounds dominating in the high latitudes of the Northern Hemisphere, and warm-dry compounds dominating in the tropics and the Southern Hemisphere. Over the past 60 years, the total frequency of compound climate anomalies was increased by 5~7 times, and the evolution trend showed significant path-dependence: warm-dry dominant regions followed a drought-intensifying pathway, whereas warm-wet dominant regions followed a wetness-intensifying pathway. The research result revealed that climate change was manifesting as a longer-cycle compound mode with stronger cumulative effects, and highlighted the urgency of incorporating consecutive compound climate anomalies into global climate risk assessment and adaptive management.