Stable climate metrics for emissions of short and long-lived species-combining steps and pulses
Stable climate metrics for emissions of short and long-lived species-combining steps and pulses
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DOI：
10.1088/1748-9326/ab6039
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发表时间：
2020-02-01
影响因子：
6.7
通讯作者：
Shine, Keith P.
中科院分区：
文献类型：
--
作者：
Collins, William J.;Frame, David J.;Shine, Keith P.
多气体气候协定依赖于一种方法（广泛称为“度量”），将不同气体的排放量置于CO2当量尺度上。关于现有指标在多大程度上服务于当前气候政策，一直存在争议。终点指标（如全球温度变化潜势GTP）与基于温度限制的政策目标（如《巴黎协定》第2条）关系最为密切。然而，对于短寿命气候强迫因子（SLCFs），端点指标随时间跨度变化很大，使其难以应用于实际情况。我们将展示如何结合一个步骤的变化SLCF排放与脉冲排放的二氧化碳的端点指标，导致一个端点指标，只在感兴趣的时间范围内缓慢变化。因此，我们建议，这些相结合的步骤脉冲指标（表示结合全球变暖潜能CGWP和结合全球温度变化潜能CGTP）可以是一个有用的方式，包括在同一篮子中的政策应用程序的短寿命和长寿命的物种，这假设一个单一的篮子的方法是首选的政策制定者。SLCF的综合阶跃脉冲度量的优点是，对于寿命不到20年的物种，约75年的单一时间范围可以覆盖适合于巴黎协定的时间尺度范围。这些指标建立在最近的工作基础上，以一种新的方式使用传统的全球变暖潜能值（GWP）指标，称为GWP*。我们展示了GWP* 如何与CGWP和CGTP相关，并且它系统地低估了SLCFs的温度效应高达20%。这些步进脉冲度量都比传统的GWP更适合比较不同物种对未来温度目标的相对贡献，对于SLCF，它们对时间范围的依赖性比GTP小得多。
Multi-gas climate agreements rely on a methodology (widely referred to as 'metrics') to place emissions of different gases on a CO2-equivalent scale. There has been an ongoing debate on the extent to which existing metrics serve current climate policy. Endpoint metrics (such as global temperature change potential GTP) are the most closely related to policy goals based on temperature limits (such as Article 2 of the Paris Agreement). However, for short-lived climate forcers (SLCFs), endpoint metrics vary strongly with time horizon making them difficult to apply in practical situations. We show how combining endpoint metrics for a step change in SLCF emissions with a pulse emission of CO2 leads to an endpoint metric that only varies slowly over time horizons of interest. We therefore suggest that these combined step-pulse metrics (denoted combined global warming potential CGWP and combined global temperature change potential CGTP) can be a useful way to include short and long-lived species in the same basket in policy applications-this assumes a single basket approach is preferred by policy makers. The advantage of a combined step-pulse metric for SLCFs is that for species with a lifetime less than 20 years a single time horizon of around 75 years can cover the range of timescales appropriate to the Paris Agreement. These metrics build on recent work using the traditional global warming potential (GWP) metric in a new way, called GWP*. We show how the GWP* relates to CGWP and CGTP and that it systematically underestimates the temperature effects of SLCFs by up to 20%. These step-pulse metrics are all more appropriate than the conventional GWP for comparing the relative contributions of different species to future temperature targets and for SLCFs they are much less dependent on time horizon than GTP.