Climate extremes such as droughts and heatwaves have a large impact on terrestrial carbon uptake by reducing gross primary production (GPP). While the evidence for increasing frequency and intensity of climate extremes over the last decades is growing, potential systematic adverse shifts in GPP have not been assessed. Using observationally-constrained and process-based model data, we estimate that particularly northern midlatitude ecosystems experienced a +10.6% increase in negative GPP extremes in the period 2000–2016 compared to 1982–1998. We attribute this increase predominantly to a greater impact of warm droughts, in particular over northern temperate grasslands (+95.0% corresponding mean increase) and croplands (+84.0%), in and after the peak growing season. These results highlight the growing vulnerability of ecosystem productivity to warm droughts, implying increased adverse impacts of these climate extremes on terrestrial carbon sinks as well as a rising pressure on global food security.

干旱和热浪等极端气候通过降低初级生产总值 (GPP) 对陆地碳吸收产生重大影响。虽然过去几十年气候极端事件频率和强度增加的证据越来越多，但尚未评估 GPP 潜在的系统性不利变化。使用受观测约束和基于过程的模型数据，我们估计，与 1982-1998 年相比，在 2000-2016 年期间，特别是北部中纬度生态系统的负 GPP 极端值增加了 +10.6%。我们将这一增长主要归因于温暖干旱的更大影响，特别是在生长旺季期间和之后的北部温带草原（相应平均增幅增加 95.0%）和农田（增加 84.0%）。