Aligning climate scenarios to emissions inventories shifts global benchmarks

Gidden, M. ORCID: https://orcid.org/0000-0003-0687-414X, Gasser, T. ORCID: https://orcid.org/0000-0003-4882-2647, Grassi, G., Forsell, N., Janssens, I., Lamb, W., Minx, J., Nicholls, Z. ORCID: https://orcid.org/0000-0002-4767-2723, et al. (2023). Aligning climate scenarios to emissions inventories shifts global benchmarks. Nature 624 102-108. 10.1038/s41586-023-06724-y.

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Project: 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)

Abstract

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.

Item Type: Article
Research Programs: Advancing Systems Analysis (ASA)
Advancing Systems Analysis (ASA) > Exploratory Modeling of Human-natural Systems (EM)
Biodiversity and Natural Resources (BNR)
Biodiversity and Natural Resources (BNR) > Integrated Biosphere Futures (IBF)
Energy, Climate, and Environment (ECE)
Energy, Climate, and Environment (ECE) > Integrated Assessment and Climate Change (IACC)
Related URLs:
Depositing User: Luke Kirwan
Date Deposited: 22 Nov 2023 17:18
Last Modified: 08 Jan 2024 07:37
URI: https://pure.iiasa.ac.at/19205

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