Using net-zero carbon debt to track climate overshoot responsibility
File(s)
Author(s)
Type
Journal Article
Abstract
Current emissions trends will likely deplete a 1.5 °C consistent carbon budget around the year 2030, resulting in at least a temporary exceedance, or overshoot. To clarify responsibilities for this budget exceedance, we consider “net-zero carbon debt,” a forward-looking measure of the extent to which a party is expected to breach its “fair share” of the remaining budget by the time it achieves net-zero carbon emissions. We apply this measure to all vetted mitigation scenarios assessed in the Intergovernmental Panel on Climate Change’s Sixth Assessment Report and two scenarios that model current policies and pledges, using an illustrative equal per capita allocation of a remaining 1.5 °C carbon budget starting in 1990. The resulting regional carbon debt estimates inform i) the scale and pace of regional carbon drawdown obligations necessary to address budget exceedance and ii) relative regional responsibilities for increased lifetime exposure to extreme heatwaves across age cohorts due to budget exceedance. Our work strengthens intergenerational equity considerations within an international climate equity discourse and informs the implementation of effort-sharing mechanisms that persist beyond the exhaustion of a rapidly dwindling remaining carbon budget.
Date Issued
2025-04-01
Date Acceptance
2025-02-10
Citation
Proceedings of the National Academy of Sciences of USA, 2025, 122 (13)
ISSN
0027-8424
Publisher
National Academy of Sciences
Start Page
e2409316122
Journal / Book Title
Proceedings of the National Academy of Sciences of USA
Volume
122
Issue
13
Copyright Statement
Copyright © 2025 the Author(s). Published by PNAS. This open access article is distributed under Creative Commons Attribution License 4.0 (CC BY).
License URL
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/40127265
Subjects
carbon debt
impacts
intergenerational equity
interregional equity
overshoot
Publication Status
Published
Coverage Spatial
United States
Article Number
e2409316122
Date Publish Online
2025-03-24