Zhou Sha, Zhang Yao, Park Williams A, Gentine Pierre
Department of Earth and Environmental Engineering, Columbia University, New York, NY 10027, USA.
Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA.
Sci Adv. 2019 Jan 23;5(1):eaau5740. doi: 10.1126/sciadv.aau5740. eCollection 2019 Jan.
Drought and atmospheric aridity pose large risks to ecosystem services and agricultural production. However, these factors are seldom assessed together as compound events, although they often occur simultaneously. Drought stress on terrestrial carbon uptake is characterized by soil moisture (SM) deficit and high vapor pressure deficit (VPD). We used in situ observations and 15 Earth system models to show that compound events with very high VPD and low SM occur more frequently than expected if these events were independent. These compound events are projected to become more frequent and more extreme and exert increasingly negative effects on continental productivity. Models project intensified negative effects of high VPD and low SM on vegetation productivity, with the intensification of SM exceeding those of VPD in the Northern Hemisphere. These results highlight the importance of compound extreme events and their threats for the capability of continents to act as a carbon sink.
干旱和大气干旱对生态系统服务和农业生产构成巨大风险。然而，尽管这些因素经常同时发生，但很少被作为复合事件一起评估。陆地碳吸收的干旱胁迫表现为土壤湿度（SM）亏缺和高水汽压亏缺（VPD）。我们利用实地观测和15个地球系统模型表明，与VPD极高和SM极低的复合事件，如果这些事件是独立发生的，其发生频率比预期更高。预计这些复合事件将变得更加频繁和极端，并对大陆生产力产生越来越大的负面影响。模型预测，高VPD和低SM对植被生产力的负面影响会加剧，在北半球，SM加剧的影响超过VPD加剧的影响。这些结果凸显了复合极端事件的重要性及其对各大洲作为碳汇能力的威胁。
