Hydroclimatic vulnerability of peat carbon in the central Congo Basin

Garcin, Y. et al. (2022) Hydroclimatic vulnerability of peat carbon in the central Congo Basin. Nature, 612(7939), pp. 277-282. (doi: 10.1038/s41586-022-05389-3) (PMID:36323786) (PMCID:PMC9729114)

Abstract

The forested swamps of the central Congo Basin store approximately 30 billion metric tonnes of carbon in peat1,2. Little is known about the vulnerability of these carbon stocks. Here we investigate this vulnerability using peat cores from a large interfluvial basin in the Republic of the Congo and palaeoenvironmental methods. We find that peat accumulation began at least at 17,500 calibrated years before present (cal. yr BP; taken as AD 1950). Our data show that the peat that accumulated between around 7,500 to around 2,000 cal. yr BP is much more decomposed compared with older and younger peat. Hydrogen isotopes of plant waxes indicate a drying trend, starting at approximately 5,000 cal. yr BP and culminating at approximately 2,000 cal. yr BP, coeval with a decline in dominant swamp forest taxa. The data imply that the drying climate probably resulted in a regional drop in the water table, which triggered peat decomposition, including the loss of peat carbon accumulated prior to the onset of the drier conditions. After approximately 2,000 cal. yr BP, our data show that the drying trend ceased, hydrologic conditions stabilized and peat accumulation resumed. This reversible accumulation–loss–accumulation pattern is consistent with other peat cores across the region, indicating that the carbon stocks of the central Congo peatlands may lie close to a climatically driven drought threshold. Further research should quantify the combination of peatland threshold behaviour and droughts driven by anthropogenic carbon emissions that may trigger this positive carbon cycle feedback in the Earth system.

• Item Type: Articles
• Additional Information: This work was funded by CongoPeat—a NERC large grant (NE/R016860/1) to S.L.L., I.T.L., S.E.P., A.B., A.J.B., P.J.M., P.G. and S.S., Agence Nationale de la Recherche (ANR) grant ANR-19-CE01-0022 to Y.G. and Deutsche Forschungsgemeinschaft (DFG) grant SCHE903/19-1 to E.S. (joint project ‘ORACLE’), Natural Environment Research Council (CASE award to S.L.L. and G.C.D.), Leeds–York NERC Doctoral Training Partnership (‘SPHERES’) award to B.C. (NE/L002574/1), NERC Radiocarbon Facility NRCF010001 (alloc. no. 1688.0313, 1797.0414, 2222.1119, 14.108 and 2329.0920 to I.T.L., S.L.L., G.E.B., B.C., P.G. and G.C.D.), Wildlife Conservation Society – Congo (to G.C.D.), the Royal Society (to S.L.L.), Philip Leverhulme Prize (to S.L.L.), and a Greenpeace Fund award (to S.L.L.). E.S. was supported by the DFG–Cluster of Excellence ‘The Ocean in the Earth System’ at MARUM. C.H.V. publishes with permission of the Executive Director of the British Geological Survey, UKRI. This study is a contribution to the International Joint Laboratory ‘Dynamics of land ecosystems in central Africa in a context of global changes’ (LMI DYCOFAC).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Gulliver, Dr Pauline
• Authors: Garcin, Y., Schefuß, E., Dargie, G. C., Hawthorne, D., Lawson, I. T., Sebag, D., Biddulph, G. E., Crezee, B., Bocko, Y. E., Ifo, S. A., Mampouya Wenina, Y. E., Mbemba, M., Ewango, C. E.N., Emba, O., Bola, P., Tabu, J. K., Tyrrell, G., Young, D. M., Gassier, G., Girkin, N. T., Vane, C. H., Adatte, T., Baird, A. J., Boom, A., Gulliver, P., Morris, P. J., Page, S. E., Sjögersten, S., and Lewis, S. L.
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Nature
• Publisher: Nature Research
• ISSN: 0028-0836
• ISSN (Online): 1476-4687
• Published Online: 02 November 2022
• Data DOI: 10.1594/PANGAEA.938019