Aligning climate scenarios to emissions inventories shifts global benchmarks

Gidden, Matthew J.; Gasser, Thomas; Grassi, Giacomo; Forsell, Nicklas; Janssens, Iris; Lamb, William F.; Minx, Jan C.; Nicholls, Zebedee; Steinhauser, Jan; Riahi, Keywan

doi:10.1038/s41586-023-06724-y

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学術論文

Aligning climate scenarios to emissions inventories shifts global benchmarks

Authors

Gidden, Matthew J.
External Organizations;

Gasser, Thomas
External Organizations;

Grassi, Giacomo
External Organizations;

Forsell, Nicklas
External Organizations;

Janssens, Iris
External Organizations;

Lamb, William F.
External Organizations;

Minx, Jan C.
External Organizations;

Nicholls, Zebedee
External Organizations;

/persons/resource/jan.steinhauser

Steinhauser, Jan
Potsdam Institute for Climate Impact Research;

Riahi, Keywan
External Organizations;

URL

https://data.ece.iiasa.ac.at/genie
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s41586-023-06724-y.pdf
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引用

Gidden, M. J., Gasser, T., Grassi, G., Forsell, N., Janssens, I., Lamb, W. F., Minx, J. C., Nicholls, Z., Steinhauser, J., & Riahi, K. (2023). Aligning climate scenarios to emissions inventories shifts global benchmarks. Nature, 624, 102-108. doi:10.1038/s41586-023-06724-y.

引用: https://publications.pik-potsdam.de/pubman/item/item_29419

要旨

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.