Aligning climate scenarios to emissions inventories shifts global benchmarks

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http://eprints.org/relation/isVersionOf https://pure.iiasa.ac.at/id/document/103642 http://eprints.org/relation/isVolatileVersionOf https://pure.iiasa.ac.at/id/document/103642 http://eprints.org/relation/isIndexCodesVersionOf https://pure.iiasa.ac.at/id/document/103642 archive 353 disk0/00/01/92/05 2023-11-22 17:18:09 2024-04-15 14:35:30 2023-11-22 17:18:09 article show 1 Gidden M. 2108 0000-0003-0687-414X Gasser T. 2136 0000-0003-4882-2647 Grassi G. Forsell N. 1999 Janssens I. 9344 Lamb W. Minx J. Nicholls Z. 2343 0000-0002-4767-2723 Steinhauser J. 2331 0000-0002-5989-6855 Riahi K. 1696 0000-0001-7193-3498 Aligning climate scenarios to emissions inventories shifts global benchmarks pub ASA EM BNR IBF ECE IACC Taking stock of global progress towards achieving the Paris Agreement requires consistently measuring aggregate national actions and pledges against modelled mitigation pathways1. However, national greenhouse gas inventories (NGHGIs) and scientific assessments of anthropogenic emissions follow different accounting conventions for land-based carbon fluxes resulting in a large difference in the present emission estimates2,3, a gap that will evolve over time. Using state-of-the-art methodologies4 and a land carbon-cycle emulator5, we align the Intergovernmental Panel on Climate Change (IPCC)-assessed mitigation pathways with the NGHGIs to make a comparison. We find that the key global mitigation benchmarks become harder to achieve when calculated using the NGHGI conventions, requiring both earlier net-zero CO2 timing and lower cumulative emissions. Furthermore, weakening natural carbon removal processes such as carbon fertilization can mask anthropogenic land-based removal efforts, with the result that land-based carbon fluxes in NGHGIs may ultimately become sources of emissions by 2100. Our results are important for the Global Stocktake6, suggesting that nations will need to increase the collective ambition of their climate targets to remain consistent with the global temperature goals. 2023-11-22 published Nature Publishing Group 10.1038/s41586-023-06724-y 103 2885 93 3756 3377 3348 250 public Nature 624 102-108 TRUE 0028-0836 https://github.com/tgasser/OSCAR https://github.com/iiasa/gidden_ar6_reanalysis https://doi.org/10.5281/zenodo.10158920 data Response of the Earth System to overshoot, Climate neUtrality and negative Emissions (RESCUE, HE 101056939) Earth system models for the future (ESM2025, H2020 101003536) GeoEngineering and NegatIve Emissions pathways in Europe (GENIE, H2020 951542) yes info:eu-repo/grantAgreement/EC/HE/101056939//RESCUE; info:eu-repo/grantAgreement/EC/H2020/101003536/EU//ESM2025; info:eu-repo/grantAgreement/EC/H2020/101003536/EU//ESM2025; info:eu-repo/grantAgreement/EC/H2020/951542/EU//GENIE info:eu-repo/semantics/article info:eu-repo/semantics/openAccess