Ratcheting ambition to limit warming to 1.5 °C–trade-offs between emission reductions and carbon dioxide removal

摘要: Mitigation scenarios to limit global warming 1.5°C or less in 2100 often rely on large amounts of carbon dioxide removal (CDR), with significant potential social, environmental, political and economic risks. A precautionary approach scenario creation is therefore indicated. This letter presents the results such a modelling exercise which models C-ROADS En-ROADS were used generate series mitigation that apply increasingly stringent constraints scale type CDR available. allows us explore trade-offs between near-term stringency emissions reductions assumptions about future availability CDR. In particular, we find regardless assumptions, ambition increase ("ratcheting") required for any pathways, making this timely facilitative, Talanoa, dialogue be conducted by UNFCCC 2018. By highlighting difference net gross reduction rates, obscured large-scale CDR, mid-term CO2 rates levels without historical precedence. turn highlights, addition need substantially improve non-CO2 greenhouse gases. Further, all part implemented as non-permanent storage exhibit loss emissions, partly offset importance differentiating scenarios. We some scenarios, trending similar values indicating would have maintained simply losses sequestered earlier, additional climate benefit.