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）在预防气候变化影响、气候变化可逆性和GGR核算方面的有效性极限。全球气温上升是由二氧化碳的累积排放决定的，气候政策的温度目标与排放预算相对应，例如2K =约1000gt C的排放。建议将GGR作为在二氧化碳排放一段时间后重新捕获二氧化碳的一种方法，使最终的净排放量达到温度目标预算。目前的气候减缓行动似乎依赖于未来GGR在这一角色中的应用，以实现《联合国气候变化框架公约》巴黎协定的国际气候变暖目标，即升温不超过2000摄氏度，理想情况下为1.5摄氏度。然而，即使达到相同的最终预算，预计由排放超调和后来的再捕获途径造成的气候变化影响将不同于与不需要再捕获的途径相关的影响。这种影响上的差异限制了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与排放预算超额的数量和持续时间的差异联系起来。MERLiN还将与国际合作伙伴一起调查气候变化的可逆性，以及地球系统（特别是碳循环）如何对GGR重新捕获的二氧化碳做出反应。在这里，碳循环成分的不同时间尺度产生惯性，因此二氧化碳的排放和后来的再捕获不具有相等（抵消）的温度效应。这给GGR带来了会计方面的挑战，MERLiN将对此进行调查和量化。这些结果对于为有关GGR的政策选择和行动提供信息至关重要。利用MERLiN研究人员丰富的政策经验，MERLiN将翻译和传播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，为政策制定者提供关于气候减缓行动、政策和机制的影响的信息。

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.