Given the short time-frame to limit global warming, and the current emissions gap, it is critical to prioritise mitigation actions. To date, scant attention has been paid to the mitigation benefits of primary forest protection. We estimated tropical forest ecosystem carbon stocks and flows. The ecosystem carbon stock of primary tropical forests is estimated at 141–159 Pg C (billion tonnes of carbon) which is some 49–53% of all tropical forest carbon, the living biomass component of which alone is 91–103% of the remaining carbon budget to limit global warming to below 1.5 degrees above pre-industrial levels. Furthermore, tropical forests have ongoing sequestration rates 0.47–1.3 Pg C yr⁻¹, equivalent to 8–13% of annual global anthropogenic CO₂ (carbon dioxide) emissions. We examined three main forest-based strategies used in the land sector—halting deforestation, increasing forest restoration and improving the sustainable management of production forests. The mitigation benefits of primary forest protection are contingent upon how degradation is defined and accounted for, while those from restoration also depend on how restoration is understood and applied. Through proforestation, reduced carbon stocks in secondary forests can regrow to their natural carbon carrying capacity or primary forest state. We evaluated published data from studies comparing logged and unlogged forests. On average, primary forests store around 35% more carbon. While comparisons are confounded by a range of factors, reported biomass carbon recovery rates were from 40 to 100+ years. There is a substantive portfolio of forest-based mitigation actions and interventions available to policy and decision-makers, depending on national circumstances, in addition to SFM and plantation focused approaches, that can be grouped into four main strategies: protection; proforestation, reforestation and restoration; reform of guidelines, accounting rules and default values; landscape conservation planning. Given the emissions gap, mitigation strategies that merely reduce the rate of emissions against historic or projected reference levels are insufficient. Mitigation strategies are needed that explicitly avoid emissions where possible as well as enabling ongoing sequestration.

鉴于限制全球变暖的时间很短，并且当前存在排放差距，因此，优先考虑缓解措施至关重要。迄今为止，对原始森林保护的缓解效益的关注很少。我们估算了热带森林生态系统的碳储量和流量。原始热带森林的生态系统碳储量估计为141-159 Pg C（十亿吨碳），约占热带森林碳总量的49-53％，其中仅生物量就占剩余生物量的91-103％碳预算将全球变暖限制在比工业化前水平低1.5度以下的水平。此外，热带森林的固存速率为0.47–1.3 Pg C yr ^-1，相当于全球每年人为二氧化碳_2的8–13％（二氧化碳）排放。我们研究了土地部门使用的三种主要的基于森林的策略-停止砍伐森林，增加森林恢复和改善生产林的可持续管理。原始森林保护的缓解效益取决于退化的定义和解决方式，而恢复带来的效益也取决于如何理解和应用恢复。通过植树造林，次生林中减少的碳储量可以恢复到其天然碳承载能力或原始森林状态。我们通过比较已砍伐森林和未砍伐森林的研究评估了发表的数据。平均而言，原始森林储存的碳大约增加35％。尽管比较受到多种因素的干扰，但报告的生物质碳回收率是40到100+年。除了可持续森林管理和以人工林为重点的方法外，根据国家情况，政策和决策者还可以从森林中获得基于森林的缓解行动和干预措施的大量资源，这些措施可以分为四个主要战略：保护；造林，再造林和恢复；改革准则，会计规则和默认值；景观保护规划。考虑到排放量差距，仅根据历史或预测参考水平降低排放率的缓解策略是不够的。需要采取缓解策略，在可能的情况下明确避免排放并实现持续的封存。除了可持续森林管理和以种植园为重点的方法外，可以将其分为四个主要战略：保护；造林，再造林和恢复；改革准则，会计规则和默认值；景观保护规划。考虑到排放量差距，仅根据历史或预测参考水平降低排放率的缓解策略是不够的。需要采取缓解策略，在可能的情况下明确避免排放并实现持续的封存。除了可持续森林管理和以种植园为重点的方法外，可以将其分为四个主要战略：保护；造林，再造林和恢复；改革准则，会计规则和默认值；景观保护规划。考虑到排放量差距，仅根据历史或预测参考水平降低排放率的缓解策略是不够的。需要采取缓解策略，在可能的情况下明确避免排放并实现持续的封存。仅根据历史或预测参考水平降低排放率的缓解策略是不够的。需要采取缓解策略，在可能的情况下明确避免排放并实现持续的封存。仅根据历史或预测参考水平降低排放率的缓解策略是不够的。需要采取缓解策略，在可能的情况下明确避免排放并实现持续的封存。