The uptake of carbon dioxide (CO₂) by terrestrial ecosystems is critical for moderating climate change¹. To provide a ground-based long-term assessment of the contribution of forests to terrestrial CO₂ uptake, we synthesized in situ forest data from boreal, temperate and tropical biomes spanning three decades. We found that the carbon sink in global forests was steady, at 3.6 ± 0.4 Pg C yr⁻¹ in the 1990s and 2000s, and 3.5 ± 0.4 Pg C yr⁻¹ in the 2010s. Despite this global stability, our analysis revealed some major biome-level changes. Carbon sinks have increased in temperate (+30 ± 5%) and tropical regrowth (+29 ± 8%) forests owing to increases in forest area, but they decreased in boreal (−36 ± 6%) and tropical intact (−31 ± 7%) forests, as a result of intensified disturbances and losses in intact forest area, respectively. Mass-balance studies indicate that the global land carbon sink has increased², implying an increase in the non-forest-land carbon sink. The global forest sink is equivalent to almost half of fossil-fuel emissions (7.8 ± 0.4 Pg C yr⁻¹ in 1990–2019). However, two-thirds of the benefit from the sink has been negated by tropical deforestation (2.2 ± 0.5 Pg C yr⁻¹ in 1990–2019). Although the global forest sink has endured undiminished for three decades, despite regional variations, it could be weakened by ageing forests, continuing deforestation and further intensification of disturbance regimes¹. To protect the carbon sink, land management policies are needed to limit deforestation, promote forest restoration and improve timber-harvesting practices^1,3.

陆地生态系统吸收二氧化碳 (CO ₂ ) 对于减缓气候变化至关重要¹ 。为了对森林对陆地 CO ₂吸收的贡献进行地面长期评估，我们综合了三十年来来自北方、温带和热带生物群落的原位森林数据。我们发现全球森林碳汇稳定，1990年代和2000年代为3.6±0.4 Pg C yr ^-1 ，2010年代为3.5±0.4 Pg C yr ^-1 。尽管全球保持稳定，但我们的分析揭示了一些主要的生物群落水平变化。由于森林面积的增加，温带森林（+30 ± 5%）和热带再生森林（+29 ± 8%）的碳汇增加，但北方森林（−36 ± 6%）和热带完整森林（−31 ± 6%）的碳汇减少7%）森林，分别是由于完整森林面积的加剧干扰和损失。质量平衡研究表明，全球陆地碳汇有所增加² ，这意味着非林地碳汇有所增加。全球森林汇相当于化石燃料排放量的近一半（1990-2019 年为 7.8 ± 0.4 Pg C yr ^-1 ）。然而，三分之二的汇效益已被热带森林砍伐抵消（1990-2019 年为 2.2 ± 0.5 Pg C yr ^-1 ）。尽管全球森林汇三十年来一直没有减少，尽管存在地区差异，但森林老化、持续砍伐和干扰制度进一步加剧可能会削弱全球森林汇¹ 。为了保护碳汇，需要制定土地管理政策来限制森林砍伐、促进森林恢复和改进木材采伐做法^1,3 。