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<p>The Tibetan Plateau is among the most climate-sensitive regions on Earth, where rising extreme drought (ED) and extreme hot (EH) events under global warming intensify hydrothermal stress. When ED and EH coincide, their compound impacts can greatly amplify ecological and societal risks in this fragile high-altitude environment. However, the compound patterns of compound extreme drought and hot events (CDHEs) have not yet been adequately elucidated, which constrains a comprehensive understanding of their spatiotemporal evolution. For this purpose, we develop a novel CDHEs identification framework using ERA5-Land data that integrates the spatiotemporal characteristics of drought and hot extremes, defines four representative CDHEs patterns— concurrent site extreme drought and hot event (COS_DH), concurrent area extreme drought and hot event (COA_DH), sequential site extreme drought and hot event (SES_DH), and sequential area extreme drought and hot event (SEA_DH)—and identifies CDHEs hotspots across the Tibet while assessing their spatiotemporal dynamics from 2000 to 2020. Results show that CDHEs are widespread and strongly clustered in time and space, with June–August being the most affected season. During this period, the monthly average duration is 6.63&#xa0;days, with hotspots in western Ngari and the Lhasa region. Across the four CDHEs modes, the mean duration reaches 8.59&#xa0;days, with SEA_DH persisting the longest (13.95&#xa0;days). All CDHEs indicators show significant upward trends, including a mean duration increase of 0.24&#xa0;days per year, with growth rates exceeding 0.30&#xa0;days per year in Nagqu, Shannan, and Lhasa. These results show the rapid intensification of CDHEs in Tibet, indicating the urgent need to strengthen early-warning systems, improve risk governance, and implement effective climate-adaptation strategies. At the same time, our approach provides valuable insights into compound climate events in other regions.</p> Graphical Abstract <p>Based on the graphical abstract, this study aims to identify and investigate the spatiotemporal distribution and evolution of compound extreme drought and hot events (CDHEs) in Tibet. In this work, we proposed and developed a novel identification workflow for compound extreme events, based on ERA5 reanalysis data from 2000 to 2020, to capture hotspot regions of CDHEs across Tibet. Specifically, considering the annual mean temperature and precipitation characteristics of the Tibetan region, the 90th percentile of the daily maximum temperature time series was applied to identify extreme hot events, while extreme drought events were identified using the Soil Moisture Deficit Index (SMDI) calculated from 0–28 cm soil moisture data. The identification of CDHEs fully incorporated both temporal and spatial characteristics, detecting four compound patterns: concurrent site extreme drought and hot event (COS_DH), concurrent area extreme drought and hot event (COA_DH), sequential site extreme drought and hot event (SES_DH), and sequential area extreme drought and hot event (SEA_DH). Theil-Sen median trend analysis and the Mann-Kendall test were employed to examine the interannual and monthly trends of CDHEs. The study identified hotspot regions of CDHEs in Tibet and further revealed spatiotemporal changes in their average duration, total duration, frequency, and number of occurrences. This plot demonstrates that CDHEs under the four compound patterns occur widely across Tibet, with 2009 exhibiting the longest average duration. A significant increasing trend in CDHEs is observed, which is particularly pronounced in the central and western regions. On a monthly scale, June and August show the fastest growth rates in the average duration of CDHEs. These findings provide a robust scientific basis for the prevention and management of CDHEs in Tibet and the broader Qinghai-Tibet Plateau region, while also offering a new perspective for the assessment and governance of compound extreme events on a global scale.</p> <p></p>

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Intensification of Compound Extreme Drought and Hot Events in Tibet: Insights from a Novel Compound Framework

  • 期刊论文

  • 发表日期：

    2025年12月29日

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  • Yaowen Ran,
  • Zegen Wang,
  • Mi Chen,
  • Xingyu Chen,
  • Jiayi Hu,
  • Chaoyue Li,
  • Zhilong Liang,
  • Zhiwei Yong,
  • Yanmei Yang

摘要

The Tibetan Plateau is among the most climate-sensitive regions on Earth, where rising extreme drought (ED) and extreme hot (EH) events under global warming intensify hydrothermal stress. When ED and EH coincide, their compound impacts can greatly amplify ecological and societal risks in this fragile high-altitude environment. However, the compound patterns of compound extreme drought and hot events (CDHEs) have not yet been adequately elucidated, which constrains a comprehensive understanding of their spatiotemporal evolution. For this purpose, we develop a novel CDHEs identification framework using ERA5-Land data that integrates the spatiotemporal characteristics of drought and hot extremes, defines four representative CDHEs patterns— concurrent site extreme drought and hot event (COS_DH), concurrent area extreme drought and hot event (COA_DH), sequential site extreme drought and hot event (SES_DH), and sequential area extreme drought and hot event (SEA_DH)—and identifies CDHEs hotspots across the Tibet while assessing their spatiotemporal dynamics from 2000 to 2020. Results show that CDHEs are widespread and strongly clustered in time and space, with June–August being the most affected season. During this period, the monthly average duration is 6.63 days, with hotspots in western Ngari and the Lhasa region. Across the four CDHEs modes, the mean duration reaches 8.59 days, with SEA_DH persisting the longest (13.95 days). All CDHEs indicators show significant upward trends, including a mean duration increase of 0.24 days per year, with growth rates exceeding 0.30 days per year in Nagqu, Shannan, and Lhasa. These results show the rapid intensification of CDHEs in Tibet, indicating the urgent need to strengthen early-warning systems, improve risk governance, and implement effective climate-adaptation strategies. At the same time, our approach provides valuable insights into compound climate events in other regions.

Graphical Abstract

Based on the graphical abstract, this study aims to identify and investigate the spatiotemporal distribution and evolution of compound extreme drought and hot events (CDHEs) in Tibet. In this work, we proposed and developed a novel identification workflow for compound extreme events, based on ERA5 reanalysis data from 2000 to 2020, to capture hotspot regions of CDHEs across Tibet. Specifically, considering the annual mean temperature and precipitation characteristics of the Tibetan region, the 90th percentile of the daily maximum temperature time series was applied to identify extreme hot events, while extreme drought events were identified using the Soil Moisture Deficit Index (SMDI) calculated from 0–28 cm soil moisture data. The identification of CDHEs fully incorporated both temporal and spatial characteristics, detecting four compound patterns: concurrent site extreme drought and hot event (COS_DH), concurrent area extreme drought and hot event (COA_DH), sequential site extreme drought and hot event (SES_DH), and sequential area extreme drought and hot event (SEA_DH). Theil-Sen median trend analysis and the Mann-Kendall test were employed to examine the interannual and monthly trends of CDHEs. The study identified hotspot regions of CDHEs in Tibet and further revealed spatiotemporal changes in their average duration, total duration, frequency, and number of occurrences. This plot demonstrates that CDHEs under the four compound patterns occur widely across Tibet, with 2009 exhibiting the longest average duration. A significant increasing trend in CDHEs is observed, which is particularly pronounced in the central and western regions. On a monthly scale, June and August show the fastest growth rates in the average duration of CDHEs. These findings provide a robust scientific basis for the prevention and management of CDHEs in Tibet and the broader Qinghai-Tibet Plateau region, while also offering a new perspective for the assessment and governance of compound extreme events on a global scale.