Tanaka Katsumasa, Boucher Olivier, Ciais Philippe, Johansson Daniel J A, Morfeldt Johannes
Laboratoire des Sciences du Climat et de l'Environnement (LSCE), Institut Pierre-Simon Laplace (IPSL), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)/Centre national de la recherche scientifique (CNRS)/Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université Paris-Saclay, Gif-sur-Yvette, France.
IPSL, CNRS/Sorbonne Université, Paris, France.
Sci Adv. 2021 May 28;7(22). doi: 10.1126/sciadv.abf9020. Print 2021 May.
Greenhouse gas (GHG) metrics, that is, conversion factors to evaluate the emissions of non-CO GHGs on a common scale with CO, serve crucial functions in the implementation of the Paris Agreement. While different metrics have been proposed, their economic cost-effectiveness has not been investigated under a range of pathways, including those substantially overshooting the temperature targets. Here, we show that cost-effective metrics for methane that minimize the overall mitigation costs are time-dependent, primarily determined by the pathway, and strongly influenced by temperature overshoot. Parties to the Paris Agreement have already adopted the conventional GWP100 (100-year global warming potential), which is shown to be a good approximation of cost-effective metrics for the coming decades. In the longer term, however, we suggest that parties consider adapting the choice of common metrics to the future pathway as it unfolds, as part of the recurring global stocktake, if global cost-effectiveness is a key consideration.
温室气体（GHG）指标，即用于在与二氧化碳相同的尺度上评估非二氧化碳温室气体排放的转换因子，在《巴黎协定》的实施中发挥着关键作用。虽然已经提出了不同的指标，但尚未在一系列情景下，包括那些大幅超过温度目标的情景下，对其经济成本效益进行研究。在此，我们表明，使总体减排成本最小化的具有成本效益的甲烷指标是随时间变化的，主要由情景决定，并受到温度超调的强烈影响。《巴黎协定》缔约方已经采用了传统的全球升温潜能值100（100年全球变暖潜能值），事实证明，这在未来几十年是具有成本效益指标的良好近似值。然而，从长远来看，如果全球成本效益是一个关键考虑因素，我们建议缔约方作为定期全球盘点的一部分，考虑随着未来情景的发展，调整通用指标的选择。
