Ecosystems play a fundamental role in climate change mitigation by photosynthetically fixing carbon from the atmosphere and storing it for a period of time in organic matter. Although climate impacts of carbon emissions by sources can be quantified by global warming potentials, the appropriate formal metrics to assess climate benefits of carbon removals by sinks are unclear. We introduce here the climate benefit of sequestration (CBS), a metric that quantifies the radiative effect of fixing carbon dioxide from the atmosphere and retaining it for a period of time in an ecosystem before releasing it back as the result of respiratory processes and disturbances. In order to quantify CBS, we present a formal definition of carbon sequestration (CS) as the integral of an amount of carbon removed from the atmosphere stored over the time horizon it remains within an ecosystem. Both metrics incorporate the separate effects of (i) inputs (amount of atmospheric carbon removal) and (ii) transit time (time of carbon retention) on carbon sinks, which can vary largely for different ecosystems or forms of management. These metrics can be useful for comparing the climate impacts of carbon removals by different sinks over specific time horizons, to assess the climate impacts of ecosystem management, and to obtain direct quantifications of climate impacts as the net effect of carbon emissions by sources versus removals by sinks.

中文翻译：

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固碳的气候效益

生态系统通过光合作用固定大气中的碳并将其存储在有机物质中一段时间​​，从而在缓解气候变化中发挥重要作用。尽管可以通过全球变暖潜力来量化碳排放源对气候的影响，但尚不清楚评估汇的碳清除对气候的好处的适当正式指标。我们在此介绍隔离的气候效益（CBS），该指标量化了从大气中固定二氧化碳并将其在生态系统中保留一段时间的辐射作用，然后由于呼吸过程和干扰而释放出二氧化碳。为了量化CBS，我们提出了碳固存（CS）的正式定义，即碳保留在生态系统内的时间范围内从大气中存储的一定数量碳的积分。这两个指标都结合了（i）输入（大气中的碳清除量）和（ii）迁移时间（碳保留时间）对碳汇的单独影响，碳汇对于不同的生态系统或管理形式可能有很大的不同。这些指标可用于比较特定时间范围内不同汇的碳清除对气候的影响，评估生态系统管理的气候影响以及获得对气候影响的直接量化，即源碳排放与碳排放的净影响。下沉。这两个指标都结合了（i）输入（大气中的碳清除量）和（ii）迁移时间（碳保留时间）对碳汇的单独影响，碳汇对于不同的生态系统或管理形式可能有很大的不同。这些指标可用于比较特定时间范围内不同汇的碳清除对气候的影响，评估生态系统管理的气候影响以及获得对气候影响的直接量化，即源碳排放与碳排放的净影响。下沉。这两个指标都结合了（i）输入（大气中的碳清除量）和（ii）迁移时间（碳保留时间）对碳汇的单独影响，碳汇对于不同的生态系统或管理形式可能有很大的不同。这些指标可用于比较特定时间范围内不同汇的碳清除对气候的影响，评估生态系统管理的气候影响以及获得对气候影响的直接量化，即源碳排放与碳排放的净影响。下沉。