Metrics for Emissions Removal Limits for Nature

Merlin是一系列模拟研究，旨在评估温室气体清除(GGR)预防气候变化影响的有效性的限度、气候变化的可逆性以及GGR的核算。全球气温上升由二氧化碳累计排放量决定，气候政策温度目标与排放预算相对应，例如2K=约1000 GT C排放。GGR被认为是在二氧化碳排放后的一段时间内重新捕获二氧化碳的一种方式，从而使最终排放的净量达到温度目标预算。目前的气候缓解行动似乎依赖于未来全球气候变化报告在这方面的应用，以实现《联合国气候变化框架公约》《巴黎协定》规定的低于2K、理想情况下升温1.5K的国际气候变暖目标。然而，即使达到相同的最终预算，预计排放超额和后来的再捕获路径造成的气候变化影响也将不同于不需要再捕获的路径的相关影响。这种影响的差异限制了GGR对避免危险的气候变化影响的贡献。Merlin旨在确定这些限制，并制定简单的指标，将承诺的气候变化影响的差异与超额排放预算的数量和持续时间联系起来。梅林还将与国际合作者一起研究气候变化的可逆性，以及地球系统(特别是碳循环)如何应对GGR重新捕获二氧化碳。在这里，碳循环组件中不同的时间尺度创造了惯性，从而二氧化碳的排放和后来的重新捕获不会产生相等的(抵消)温度效应。这为GGR带来了会计挑战，梅林将对此进行调查和量化。这些结果对于指导GGR的政策选择和行动至关重要。利用梅林研究员丰富的政策经验，梅林将翻译和传达其关于气候变化影响GGR限制、气候变化可逆性和GGR核算的研究结果，以向政策制定者通报对气候缓解行动、政策和机制的影响。

MERLiN is series of modelling studies designed to assess the limits of Greenhouse Gas Removal (GGR) effectiveness for prevention of climate change impacts, climate change reversibility, and the accounting of GGR. Global temperature rise is determined by cumulative emissions of CO2, with climate policy temperature targets corresponding to emissions budgets e.g. 2K = around 1000 Gt C emitted. GGR is suggested as a way of recapturing CO2 some time after it has been emitted such that the eventual net quantity emitted meets a temperature target budget. Current climate mitigation action appears reliant on future application of GGR in this role to meet the international climate warming targets of the UNFCCC Paris Agreement of less than 2K and ideally 1.5K warming. However, even if the same eventual budget is attained, it is expected that climate change impacts resulting from an emissions overshoot and later recapture pathway will be different to impacts associated with pathways in which no recapture is required. This difference in impacts sets limits to the contribution of GGR to avoiding dangerous climate change impacts. MERLiN is designed to determine these limits, and develop simple metrics relating the difference in committed climate change impacts to the amount and duration of emissions budget excess. MERLiN will also, with international collaborators, investigate climate change reversibility, and how the Earth system (in particular the carbon cycle) respond to GGR recapture of CO2. Here, different timescales in carbon cycle components create inertia whereby emission and later recapture of CO2 do not have equal (cancelling) temperature effect. This creates an accounting challenge for GGR which MERLiN will investigate and quantify.These results are crucial to informing policy choices and actions on GGR. Using MERLiN researcher's strong policy experience, MERLiN will translate and communicate its findings on climate change impact GGR limits, climate change reversibility, and GGR accounting to inform policy-makers on the implications for climate mitigation action, policies and mechanisms.