Towards More Pragmatic Global Climate Goals and Policies

About the ProjectThis study examines potentially efficient global decarbonisation pathways that incorporate mitigation and adaptation to achieve more cost-effective outcomes. It forms part of a joint research program into practical approaches to climate change policy being undertaken by KAPSARC and the Institute of Energy Economics, Japan (IEEJ). This research program aims to help inform the debate around the development of more practical and cost-effective ways to help close the gap between national contributions and agreed global goals in the context of future climate negotiations.Key PointsThis paper presents an analysis of the climate and economic impacts of four different carbon emission scenarios. The scenarios include: a ‘business as usual’ reference scenario; a carbon emission mitigation scenario designed to meet the Paris Agreement goal of limiting average global temperature increases to no more than 2o Celsius (C) by 2100; and two scenarios that seek to optimize global welfare taking into account the total costs associated with carbon mitigation, adaptation and damage, one with more rapidly declining low-carbon or zero-carbon technology costs after 2050. Key insights include the following:Under the optimal global welfare case with more rapidly declining technology costs after 2050, global average temperature increases peak at between 2.3oC and 2.7oC, which is above the level achieved under the 2oC by 2100 scenario.However, the 2o C scenario, which relies exclusively on mitigation responses, requires very high carbon prices to achieve its goals; above $250/ton carbon dioxide equivalent (CO2 e) by 2050 and over $1,200/ton CO2 e in 2100 (prices are in real 2014 U.S. dollars). This is reflected in a disproportionately high total economic cost between now and 2100, reaching around 4 percent of global gross domestic product (GDP) by 2090.By comparison, carbon prices associated with the optimal global welfare cases are less than $50/ ton CO2 e by 2050, and between $175/ton CO2 e (standard optimal case) and $300/ton CO2 e (optimal case with more rapidly declining technology costs) in 2100. The total economic costs under the optimal global welfare scenarios never exceed 3 percent of global GDP, with the cost peaking at 2.6 percent of global GDP around 2130 under the optimal scenario, with more rapidly declining technology development costs after 2050.This analysis suggests that a more pragmatic approach to tackling climate change (referred to as a practical approach hereafter) which balances mitigation, adaptation and damage is likely to minimize the overall cost to society. It also highlights the potential economic benefits associated with accelerating the development and deployment of cost effective low- and zero-carbon technologies. Governments have a crucial role to play to support effective research and development in this context. Scope remains to develop more practical and flexible approaches to climate policy that are clear, predictable and able to effectively evolve as the transition to a decarbonized global economy unfolds.

关于本项目本研究探讨了一系列可能高效的全局脱碳路径，这些路径综合了减缓与适应措施，以实现更具成本效益的结果。该研究是KAPSARC与日本能源经济研究所（IEEJ）共同开展的一项关于气候变化政策实际途径的研究计划的一部分。该研究计划旨在为未来气候谈判背景下，探讨更实用且成本效益更高的国家贡献与全球目标差距缩小方法提供信息。主要观点本文分析了四种不同碳排放情景下的气候与经济影响。情景包括：‘现状不变’参考情景；旨在满足《巴黎协定》目标，即限制全球平均温度在2100年前不超过2摄氏度（°C）的碳排放减缓情景；以及两种寻求优化全球福利的情景，这些情景在考虑碳减缓、适应和损害的总成本的基础上，一种在2050年后低碳或零碳技术成本迅速下降。主要见解包括以下内容：在2050年后技术成本迅速下降的最优全球福利案例中，全球平均温度上升峰值介于2.3°C至2.7°C之间，高于2100年前实现2°C的情景。然而，仅依靠减缓应对措施的2°C情景，需要非常高的碳价格来实现其目标；到2050年碳价格需超过250美元/吨二氧化碳当量（CO2 e），到2100年超过1200美元/吨CO2 e（均为2014年美国实际美元）。这反映在从现在到2100年的总经济成本不成比例地高，到2090年达到全球国内生产总值（GDP）的约4%。相比之下，与最优全球福利案例相关的碳价格到2050年不到50美元/吨CO2 e，到2100年为175美元/吨CO2 e（标准最优案例）至300美元/吨CO2 e（技术成本迅速下降的最优案例）。在最优全球福利情景下，总经济成本从未超过全球GDP的3%，在2050年后技术发展成本迅速下降的最优情景下，成本峰值约为2130年的全球GDP的2.6%。该分析表明，一种更务实的气候变化应对方法（以下简称实用方法），在平衡减缓、适应和损害之间，可能有助于最小化对社会的整体成本。它还突出了加速开发和部署成本效益高的低碳和零碳技术的潜在经济收益。政府在支持有效的研究与开发方面发挥着至关重要的作用。当前仍需发展更实用、更灵活的气候政策方法，这些方法清晰、可预测，并能有效地随着向低碳全球经济的转型而演变。