Assessing the relative costs of high-CCS and low-CCS pathways to 1.5 degrees

Almost all decarbonisation scenarios consistent with the 1.5°C target in the Paris Agreement contain some level of carbon capture and storage (CCS), either for abating emissions at source, removing carbon dioxide from the atmosphere, or both.1 But the amount of CCS varies widely.2 Therefore the scenarios, even when analysed in reports from the Intergovernmental Panel on Climate Change (IPCC), do not show policymakers a single ‘optimum’ or even ‘preferable’ pathway to 1.5°C, leaving room for alternative interpretations based on different priorities. And yet the timescale available for enacting policies to deliver such a pathway is extremely tight, with carbon emissions needing to halve before 2030, alongside major reductions in emissions of other greenhouse gases such as methane, and reach net zero around mid-century. In this report we assess the relative costs of low-CCS and high-CCS pathways to 1.5°C using scenarios developed for the IPCC’s Sixth Assessment Report (AR6). 2 Using a range of criteria, we select a ‘high-CCS’ group of scenarios and a ‘low-CCS’ group. On average, as a fraction of emissions today, the high-CCS scenarios deliver about half of the CO2 emissions reductions needed in 2050 via CCS, while in low-CCS scenarios on average this fraction is about one-tenth.a The scenarios include all types of CCS, including on power stations, industrial facilities, BECCS and DACCS. All scenarios selected are compatible with the 1.5°C temperature goal, with varying degrees of overshoot, and all reach net zero CO2 emissions around mid-century. We then assess the cost of each scenario using a methodology developed by one of us (RW) and published last year.