Forests are currently a substantial carbon sink globally. Many climate change mitigation strategies leverage forest preservation and expansion, but rely on forests storing carbon for decades to centuries. Yet climate-driven disturbances pose critical risks to the long-term stability of forest carbon. We quantify the climate drivers that influence wildfire and climate stress-driven tree mortality, including a separate insect-driven tree mortality, for the contiguous United States for current (1984–2018) and project these future disturbance risks over the 21st century. We find that current risks are widespread and projected to increase across different emissions scenarios by a factor of >4 for fire and >1.3 for climate-stress mortality. These forest disturbance risks highlight pervasive climate-sensitive disturbance impacts on US forests and raise questions about the risk management approach taken by forest carbon offset policies. Our results provide US-wide risk maps of key climate-sensitive disturbances for improving carbon cycle modeling, conservation and climate policy.

中文翻译：

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美国森林的压力、昆虫和火灾带来的未来气候风险

森林目前是全球重要的碳汇。许多气候变化缓解战略利用森林保护和扩张，但依赖于森林储存碳数十年至数百年。然而，气候驱动的干扰对森林碳的长期稳定性构成了重大风险。我们量化了影响野火和气候压力驱动的树木死亡率的气候驱动因素，包括当前（1984-2018 年）美国毗连的昆虫驱动的树木死亡率，并预测 21 世纪这些未来的干扰风险。我们发现，目前的风险很普遍，并且预计在不同的排放情景中，火灾风险会增加 >4，气候压力死亡率会增加 >1.3。这些森林干扰风险突出了对美国森林普遍存在的气候敏感干扰影响，并对森林碳抵消政策所采取的风险管理方法提出了质疑。我们的结果为改进碳循环建模、保护和气候政策提供了美国范围内关键气候敏感扰动的风险图。