Great hope is being placed in the ability of forest ecosystems to contribute to greenhouse gas (GHG) emission reduction targets to limit global warming. Many nations plan to rely on forest-based climate mitigation activities to create additional and long-term carbon sequestration. Here, we take a critical look at the state of the policy and ecology surrounding forest-based natural climate solutions (NCS), with a focus on temperate forests of the United States (US). We first provide a high-level overview of carbon accounting, including key concepts used in the monitoring, reporting and verification of forest-based NCS. Second, we provide a high-level overview of forest carbon dynamics, including pools and fluxes, and drivers of their change. We then identify gaps in the current systems of GHG accounting, and between current ambitions and basic forest ecology. Improved use of data in models provides a path forward to better assessment and anticipation of forest-based climate mitigation. We illustrate this with the creation of a climate-sensitive forestry model, using tree-ring time series data. This climate-sensitive forest simulator will improve planning of site-level climate mitigation activities in the US by providing more realistic expectations of the carbon sequestration potential of forests undergoing climate change. Our review highlights the sobering complexity and uncertainty surrounding forest carbon dynamics, along with the need to improve carbon accounting. If we are to expect forests to play the significant emissions reduction role that is currently planned, we should view immediate emissions reductions as critical to preserve the climate mitigation capacity of forest ecosystems.

人们寄希望于森林生态系统能够为温室气体 (GHG) 减排目标做出贡献，以限制全球变暖。许多国家计划依靠以森林为基础的气候减缓活动来创造额外的长期碳封存。在这里，我们对围绕基于森林的自然气候解决方案 (NCS) 的政策和生态状况进行了批判性研究，重点关注美国 (US) 的温带森林。我们首先提供碳核算的高级概述，包括用于监测、报告和验证基于森林的 NCS 的关键概念。其次，我们提供了森林碳动态的高层次概述，包括碳汇和通量，以及它们变化的驱动因素。然后，我们确定当前温室气体核算系统中的差距，在当前的野心和基本的森林生态之间。改进模型中数据的使用为更好地评估和预测基于森林的气候缓解措施提供了一条途径。我们通过使用树木年轮时间序列数据创建气候敏感型林业模型来说明这一点。这种对气候敏感的森林模拟器将通过对经历气候变化的森林的碳封存潜力提供更现实的预期，从而改进美国现场级气候减缓活动的规划。我们的审查强调了围绕森林碳动态的发人深省的复杂性和不确定性，以及改进碳核算的必要性。如果我们期望森林发挥目前计划中的显着减排作用，