Bomb radiocarbon evidence for strong global carbon uptake and turnover in terrestrial vegetation
Radiocarbon from 1960s bomb tests reveals global NPP is higher than models suggest, largely due to overlooked carbon in short‑lived plant tissues. Plants store more carbon than recognized, but for shorter periods, adding uncertainty to carbon‑cycle projections and highlighting the need to refine NPP estimates.
Subject Tags
- Carbon storage
- Climate impacts
- Biodiversity
Abstract
Vegetation and soils are taking up approximately 30% of anthropogenic carbon dioxide emissions because of small imbalances in large gross carbon exchanges from productivity and turnover that are poorly constrained. We combined a new budget of radiocarbon produced by nuclear bomb testing in the 1960s with model simulations to evaluate carbon cycling in terrestrial vegetation. We found that most state-of-the-art vegetation models used in the Coupled Model Intercomparison Project underestimated the radiocarbon accumulation in vegetation biomass. Our findings, combined with constraints on vegetation carbon stocks and productivity trends, imply that net primary productivity is likely at least 80 petagrams of carbon per year presently, compared with the 43 to 76 petagrams per year predicted by current models. Storage of anthropogenic carbon in terrestrial vegetation is likely more short-lived and vulnerable than previously predicted.
Citation
Graven, H.D., Warren, H., Gibbs, H.K., Khatiwala, S., Koven, C., Lester, J., Levin, I., Spawn-Lee, S.A. and Wieder, W., 2024. Bomb radiocarbon evidence for strong global carbon uptake and turnover in terrestrial vegetation. Science, 384(6702), pp.1335-1339. 10.1126/science.adl444
TNC Authors
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Seth Spawn-Lee
Spatial Scientist, North America
The Nature Conservancy
Email: seth.spawn-lee@tnc.org