Minimal impact of recent decline in C₄ vegetation abundance on atmospheric carbon isotopic composition
File(s)
Published version
Author(s)
Lavergne, Alienor
Harrison, Sandy P
Atsawawaranunt, Kamolphat
Dong, Ning
Prentice, Iain Colin
Type
Journal Article
Abstract
Changes in atmospheric carbon dioxide concentrations, climate, and land management influence the abundance and distribution of C3 and C4 plants, yet their impact on the global carbon cycle remains uncertain. Here, we use a parsimonious model of C3 and C4 plant distribution, based on optimality principles, combined with a simplified representation of the global carbon cycle, to assess how shifts in plant abundances driven by carbon dioxide and climate affect global gross primary production, land-based carbon isotope discrimination, and the isotopic composition of atmospheric carbon dioxide. We estimate that the proportion of C4 plants in total biomass declined from about 16% to 12% between 1982 and 2016, despite an increase in the abundance of C4 crops. This decline reflects the reduced competitive advantage of C4 photosynthesis in a carbon dioxide-enriched atmosphere. As a result, global gross primary production rose by approximately 16.5 ± 1.8 petagrams of carbon, and land-based carbon isotope discrimination increased by 0.017 ± 0.001‰ per year. Accounting for changes in C3 and C4 abundances reduces the difference between observed and modelled trends in atmospheric carbon isotope composition, but does not fully explain the observed decrease, pointing to additional, unaccounted drivers.
Date Issued
2026-01-28
Date Acceptance
2025-12-05
Citation
Communications Earth & Environment, 2026, 7
ISSN
2662-4435
Publisher
Nature Portfolio
Journal / Book Title
Communications Earth & Environment
Volume
7
Copyright Statement
© The Author(s) 2026 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
License URL
Publication Status
Published
Article Number
93
Date Publish Online
2026-01-10