近日，美国加州大学伯克利分校Jeffrey Q. Chambers团队认为亚马逊的炎热干旱为未来的热带气候提供了一扇窗户。2025年12月10日出版的《自然》杂志发表了这项成果。

热带森林是地球上最温暖湿润的生物群落，但持续的人为变暖正将其推向史无前例的气候状态。随着热带地区气温逐次攀升，干旱已愈发严重。

研究组综合多组数据集，评估了极端高温干旱对亚马逊中部森林的影响。首先，一项选择性采伐实验提供的逾30年森林年度群落动态数据显示，极端干旱期间树木死亡率显著上升，尤其是木质密度较低的速生先锋树种。其次，通过对2015年和2023年厄尔尼诺干旱事件的生态生理学实地测量分析，研究组确定了导致树木蒸腾速率急剧下降的土壤湿度临界阈值。当无雨日持续突破该阈值时，干旱持续加剧，树木因水力衰竭与碳饥饿而死亡的风险也随之升高。

第三，耦合模式比较计划第六阶段的分析表明，在高排放情景下，到2100年将有大面积热带森林转为更炎热的"超热带气候"。最后，在超热带气候条件下，典型旱季的温度与湿度将更频繁地突破已确定的干旱致死阈值，从而加剧森林退化风险。当前的高温干旱正是这种新兴气候的预兆，为学界研究未来极端气候下的热带森林提供了窗口。

附：英文原文

Title: Hot droughts in the Amazon provide a window to a future hypertropical climate

Author: Chambers, Jeffrey Q., Nogueira Lima, Adriano Jos, Pastorello, Gilberto, Gimenez, Bruno Oliva, Meng, Lin, Dyer, Lee A., Feng, Yanlei, Santos da Silva, Cristina, Costa de Oliveira, Regison, Weber, Anna, Koven, Charlie, Negrn-Jurez, Robinson, Spanner, Gustavo C., Gaui, Tatiana D., Fontes, Clarissa G., de Arajo, Alessandro C., McDowell, Nate, Leung, Ruby, Marra, Daniel Magnabosco, Warren, Jeffrey, Celestina Souza, Daisy, Wright, Cynthia, Jardine, Kolby, Longo, Marcos, Xu, Chonggang, Fine, Paul V. A., Fisher, Rosie A., Tomasella, Javier, dos Santos, Joaquim, Higuchi, Niro

Issue&Volume: 2025-12-10

Abstract: Tropical forests represent the warmest and wettest of Earth’s biomes, but with continued anthropogenic warming, they will be pushed to climate states with no current analogue1,2. Droughts in the tropics are already becoming more intense as they occur at successively higher temperatures3,4,5. Here we synthesize multiple datasets to assess the effects of hot droughts on a central Amazon forest. First, a more than 30-year record of annually resolved forest demographic data from a selective logging experiment showed higher tree mortality during intense droughts, particularly among fast-growing pioneer species with low wood density. Second, analysis of ecophysiological field measurements from the 2015 and 2023 El Nio droughts identified a soil moisture threshold beyond which transpiration rates rapidly declined. As rainless days beyond this threshold continued, drought conditions intensified, increasing the potential for tree mortality from hydraulic failure and carbon starvation. Third, analyses from the Coupled Model Intercomparison Project Phase 6 demonstrated that under high-emission scenarios, a large area of tropical forest will shift to a hotter ‘hypertropical’ climate by 2100. Last, under a hypertropical climate, temperature and moisture conditions during typical dry season months will more frequently exceed identified drought mortality thresholds, elevating the risk of forest dieback. Present-day hot droughts are harbingers of this emerging climate, offering a window for studying tropical forests under expected extreme future conditions6,7,8.

DOI: 10.1038/s41586-025-09728-y

Source: https://www.nature.com/articles/s41586-025-09728-y