International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria.
School of Geography and the Environment, University of Oxford, Oxford, UK.
Nature. 2021 Aug;596(7872):377-383. doi: 10.1038/s41586-021-03723-9. Epub 2021 Jul 8.
The remaining carbon budget for limiting global warming to 1.5 degrees Celsius will probably be exhausted within this decade. Carbon debt generated thereafter will need to be compensated by net-negative emissions. However, economic policy instruments to guarantee potentially very costly net carbon dioxide removal (CDR) have not yet been devised. Here we propose intertemporal instruments to provide the basis for widely applied carbon taxes and emission trading systems to finance a net-negative carbon economy. We investigate an idealized market approach to incentivize the repayment of previously accrued carbon debt by establishing the responsibility of emitters for the net removal of carbon dioxide through 'carbon removal obligations' (CROs). Inherent risks, such as the risk of default by carbon debtors, are addressed by pricing atmospheric CO storage through interest on carbon debt. In contrast to the prevailing literature on emission pathways, we find that interest payments for CROs induce substantially more-ambitious near-term decarbonization that is complemented by earlier and less-aggressive deployment of CDR. We conclude that CROs will need to become an integral part of the global climate policy mix if we are to ensure the viability of ambitious climate targets and an equitable distribution of mitigation efforts across generations.
在本世纪内，将全球变暖限制在 1.5 摄氏度以内的剩余碳预算可能将耗尽。此后产生的碳债务将需要通过净负排放来补偿。然而，尚未设计出用于保证潜在非常昂贵的二氧化碳净去除（CDR）的经济政策工具。在这里，我们提出了跨期工具，为广泛应用的碳税和排放交易系统提供基础，以资助净负碳排放经济。我们通过“碳去除义务”（CRO）来激励排放者为二氧化碳的净去除承担责任，从而调查了一种理想化的市场方法，以激励偿还以前累积的碳债务。通过对碳债务征收利息来为大气 CO 储存定价，可以解决碳债务违约等固有风险。与关于排放途径的主流文献相反，我们发现 CRO 的利息支付会促使近期脱碳更加积极，同时更早地采用 CDR 技术。我们得出结论，如果要确保雄心勃勃的气候目标和缓解努力在代际间公平分配的可行性，那么 CRO 将需要成为全球气候政策组合的一个组成部分。
