The storage of organic carbon in the terrestrial biosphere directly affects atmospheric concentrations of carbon dioxide over a wide range of timescales. Within the terrestrial biosphere, the magnitude of carbon storage can vary in response to environmental perturbations such as changing temperature or hydroclimate1, potentially generating feedback on the atmospheric inventory of carbon dioxide. Although temperature controls the storage of soil organic carbon at mid and high latitudes2,3, hydroclimate may be the dominant driver of soil carbon persistence in the tropics4,5; however, the sensitivity of tropical soil carbon turnover to large-scale hydroclimate variability remains poorly understood. Here we show that changes in Indian Summer Monsoon rainfall have controlled the residence time of soil carbon in the Ganges–Brahmaputra basin over the past 18,000 years. Comparison of radiocarbon ages of bulk organic carbon and terrestrial higher-plant biomarkers with co-located palaeohydrological records6 reveals a negative relationship between monsoon rainfall and soil organic carbon stocks on a millennial timescale. Across the deglaciation period, a depletion of basin-wide soil carbon stocks was triggered by increasing rainfall and associated enhanced soil respiration rates. Our results suggest that future hydroclimate changes in tropical regions are likely to accelerate soil carbon destabilization, further increasing atmospheric carbon dioxide concentrations.
This is a preview of subscription content
Subscription info for Chinese customers
We have a dedicated website for our Chinese customers. Please go to naturechina.com to subscribe to this journal.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
All new data produced for this study are from samples from Bengal Fan cores SO93-117KL, -118KL and -120KL. These are available in Supplementary Tables and online in the EarthChem Library (http://www.earthchem.org/). Specifically, these present a compilation of radiocarbon age-dating results from planktonic foraminifera used in derivation of core age-depth models (Supplementary Table 1 and https://doi.org/10.1594/IEDA/111486); results of radiocarbon analyses of bulk organic carbon and calculated reservoir offset and F14R values of bulk and millennial BOC (Supplementary Table 2 and https://doi.org/10.1594/IEDA/111487); results of radiocarbon analyses of fatty-acid homologues and associated calculated reservoir offset and F14R values of bulk homologues and the subset of those cycled on millennial timescales (Supplementary Table 3 and https://doi.org/10.1594/IEDA/111488); and abundances of fatty-acid homologues (Supplementary Table 4 and https://doi.org/10.1594/IEDA/111489). Source data for Figs. 1, 2 and Extended Data Figs. 2–7 are provided with the paper.
Davidson, E. A. & Janssens, I. A. Temperature sensitivity of soil carbon decomposition and feedbacks to climate change. Nature 440, 165–173 (2006).
Melillo, J. M. et al. Soil warming and carbon-cycle feedbacks to the climate system. Science 298, 2173–2176 (2002).
Lloyd, J. & Taylor, J. A. On the temperature dependence of soil respiration. Funct. Ecol. 8, 315–323 (1994).
Carvalhais, N. et al. Global covariation of carbon turnover times with climate in terrestrial ecosystems. Nature 514, 213–217 (2014).
Bloom, A. A., Exbrayat, J. F., van der Velde, I. R., Feng, L. & Williams, M. The decadal state of the terrestrial carbon cycle: global retrievals of terrestrial carbon allocation, pools, and residence times. Proc. Natl Acad. Sci. USA 113, 1285–1290 (2016).
Hein, C. J., Galy, V. V., Galy, A., France-Lanord, C. & Kudrass, H. Post-glacial climate forcing of surface processes in the Ganges–Brahmaputra river basin and implications for carbon sequestration. Earth Planet. Sci. Lett. 478, 89–101 (2017).
Friend, A. D. et al. Carbon residence time dominates uncertainty in terrestrial vegetation responses to future climate and atmospheric CO2. Proc. Natl Acad. Sci. USA 111, 3280–3285 (2014).
Xia, J. et al. Terrestrial carbon cycle affected by non-uniform climate warming. Nat. Geosci. 7, 173–180 (2014).
Hicks Pries, C. E. H., Castanha, C., Porras, R. C. & Torn, M. S. The whole-soil carbon flux in response to warming. Science 355, 1420–1423 (2017).
Schimel, D., Stephens, B. B. & Fisher, J. B. Effect of increasing CO2 on the terrestrial carbon cycle. Proc. Natl Acad. Sci. USA 112, 436–441 (2015).
Wieder, W. R., Cleveland, C. C., Smith, W. K. & Todd-Brown, K. Future productivity and carbon storage limited by terrestrial nutrient availability. Nat. Geosci. 8, 441–444 (2015).
Simpson, G. & Castelltort, S. Model shows that rivers transmit high-frequency climate cycles to the sedimentary record. Geology 40, 1131–1134 (2012).
Aufdenkampe, A. K. et al. Organic matter in the Peruvian headwaters of the Amazon: compositional evolution from the Andes to the lowland Amazon mainstem. Org. Geochem. 38, 337–364 (2007).
Drenzek, N. et al. A new look at old carbon in active margin sediments. Geology 37, 239–242 (2009).
Hilton, R. G., Galy, A., Hovius, N. & Horng, M. J. Efficient transport of fossil organic carbon to the ocean by steep mountain rivers: an orogenic carbon sequestration mechanism. Geology 39, 71–74 (2011).
Schefuß, E. et al. Hydrologic control of carbon cycling and aged carbon discharge in the Congo River basin. Nat. Geosci. 9, 687–690 (2016).
Galy, V. & Eglinton, T. I. Protracted storage of biospheric carbon in the Ganges–Brahmaputra basin. Nat. Geosci. 4, 843–847 (2011).
Soulet, G., Skinner, L. C., Beaupré, S. R. & Galy, V. A note on reporting of reservoir 14C disequilibria and age offsets. Radiocarbon 58, 205–211 (2016).
French, K. L. et al. Millennial soil retention of terrestrial organic carbon matter deposited in the Bengal Fan. Sci. Rep. 8, 11997 (2018).
Yu, H. et al. Soil carbon release responses to long-term versus short-term climatic warming in an arid ecosystem. Biogeosci. 17, 781–792 (2020).
Milliman, J. D. & Syvitski, J. P. Geomorphic/tectonic control of sediment discharge to the ocean: the importance of small mountainous rivers. J. Geol. 100, 525–544 (1992).
Galy, V. et al. Efficient organic carbon burial in the Bengal fan sustained by the Himalayan erosional system. Nature 450, 407–410 (2007).
Galy, V., Peucker-Ehrenbrink, B. & Eglinton, T. Global carbon export from the terrestrial biosphere controlled by erosion. Nature 521, 204–207 (2015).
France-Lanord, C. & Derry, L. A. Organic carbon burial forcing of the carbon cycle from Himalayan erosion. Nature 390, 65–67 (1997).
Roxy, M. K. et al. Drying of Indian subcontinent by rapid Indian Ocean warming and a weakening land-sea thermal gradient. Nat. Commun. 6, 7423 (2015).
Gustafsson, Ö., Van Dongen, B. E., Vonk, J. E., Dudarev, O. V. & Semiletov, I. P. Widespread release of old carbon across the Siberian Arctic echoed by its large rivers. Biogeosciences 8, 1737–1743 (2011).
Ciais, P. et al. Large inert carbon pool in the terrestrial biosphere during the Last Glacial Maximum. Nat. Geosci. 5, 74–79 (2012).
Christensen, J. H. et al. in Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (eds Stocker, T. F. et al.) 1217–1308 (Cambridge University Press, 2013).
Sharmila, S., Joseph, S., Sahai, A. K., Abhilash, S. & Chattopadhyay, R. Future projection of Indian summer monsoon variability under climate change scenario: an assessment from CMIP5 climate models. Global Planet. Change 124, 62–78 (2015).
Kawamura, K. et al. Northern Hemisphere forcing of climatic cycles in Antarctica over the past 360,000 years. Nature 448, 912–916 (2007).
Cheng, H. et al. The Asian monsoon over the past 640,000 years and ice age terminations. Nature 534, 640–646 (2016); corrigendum 541, 122 (2016).
Weber, M. E., Wiedicke, M. H., Kudrass, H. R., Hübscher, C. & Erlenkeuser, H. Active growth of the Bengal Fan during sea-level rise and highstand. Geology 25, 315–318 (1997).
Bronk Ramsey, C. B. Bayesian analysis of radiocarbon dates. Radiocarbon 51, 337–360 (2009).
Reimer, P. J. et al. IntCal13 and Marine13 radiocarbon age calibration curves 0–50,000 years cal BP. Radiocarbon 55, 1869–1887 (2013).
Dutta, K., Bhushan, R. & Somayajulu, B. ΔR correction values for the northern Indian Ocean. Radiocarbon 43, 483–488 (2001).
Southon, J., Kashgarian, M., Fontugne, M., Metivier, B. & Yim, W. W. Marine reservoir corrections for the Indian Ocean and Southeast Asia. Radiocarbon 44, 167–180 (2002).
Blaauw, M. Methods and code for ‘classical’ age-modelling of radiocarbon sequences. Quat. Geochronol. 5, 512–518 (2010).
Christl, M. et al. The ETH Zurich AMS facilities: performance parameters and reference materials. Nucl. Instrum. Methods Phys. Res. B 294, 29–38 (2013).
Eglinton, T. I. et al. Gas chromatographic isolation of individual compounds from complex matrices for radiocarbon dating. Anal. Chem. 68, 904–912 (1996).
Santos, G. M. et al. Blank assessment for ultra-small radiocarbon samples: chemical extraction and separation versus AMS. Radiocarbon 52, 1322–1335 (2010).
Shah Walter, S. R. et al. Ultra-small graphitization reactors for ultra-microscale 14C analysis at the National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) facility. Radiocarbon 57, 109–122 (2015).
Kusch, S., Rethemeyer, J., Schefuß, E. & Mollenhauer, G. Controls on the age of vascular plant biomarkers in Black Sea sediments. Geochim. Cosmochim. Acta 74, 7031–7047 (2010).
Ohkouchi, N., Eglinton, T. I. & Hayes, J. M. Radiocarbon dating of individual fatty acids as a tool for refining Antarctic margin sediment chronologies. Radiocarbon 45, 17–24 (2003).
Olsson, I. U. (ed). Radiocarbon Variations and Absolute Chronology: Nobel Symposium, 12th Proc. (John Wiley, 1970).
Stuiver, M. & Polach, H. A. Discussion: reporting of 14C data. Radiocarbon 19, 355–363 (1977).
Reimer, P. J., Brown, T. A. & Reimer, R. W. Discussion: reporting and calibration of post-bomb 14C data. Radiocarbon 46, 1299–1304 (2004).
Soulet, G. Methods and codes for reservoir–atmosphere 14C age offset calculations. Quat. Geochronol. 29, 97–103 (2015).
Galy, V., Beyssac, O., France-Lanord, C. & Eglinton, T. I. Recycling of graphite during Himalayan erosion: a geological stabilization of carbon in the crust. Science 322, 943–945 (2008).
Galy, V., Hein, C., France-Lanord, C. & Eglinton, T. in Biogeochemical Dynamics at Major River-Coastal Interfaces: Linkages with Global Change (eds Bianchi, T., Allison, M. & Cai, W.-J.) 353–372 (Cambridge Univ. Press, 2014).
Lupker, M., France-Lanord, C., Galy, V., Lavé, J. & Kudrass, H. Increasing chemical weathering in the Himalayan system since the Last Glacial Maximum. Earth Planet. Sci. Lett. 365, 243–252 (2013).
Lambeck, K. & Chappell, J. Sea-level change through the last glacial cycle. Science 292, 679–686 (2001).
Clark, P. U. et al. The last glacial maximum. Science 325, 710–714 (2009).
Collins, J. A. et al. Estimating the hydrogen isotopic composition of past precipitation using leaf-waxes from western Africa. Quat. Sci. Rev. 65, 88–101 (2013).
Galy, V., Eglinton, T., France-Lanord, C. & Sylva, S. The provenance of vegetation and environmental signatures encoded in vascular plant biomarkers carried by the Ganges–Brahmaputra rivers. Earth Planet. Sci. Lett. 304, 1–12 (2011).
Schwenk, T., Spieß, V., Hübscher, C. & Breitzke, M. Frequent channel avulsions within the active channel–levee system of the middle Bengal Fan—an exceptional channel–levee development derived from Parasound and Hydrosweep data. Deep Sea Res. Part II Top. Stud. Oceanogr. 50, 1023–1045 (2003).
We thank C. Johnson (Woods Hole Oceanographic Institution, WHOI) and D. Montluçon (ETH Zürich) for laboratory support. We thank H. Kudrass for assistance with core sampling. This work was supported by a WHOI Coastal Ocean Institute Postdoctoral Fellowship to C.J.H., and by the National Science Foundation (grant numbers OCE-1333826, OCE-1333387 and OCE-1657771). This is contribution number 3868 of the Virginia Institute of Marine Science.
The authors declare no competing interests.
Peer review information Nature thanks Katherine Freeman, Sanjeev Gupta, Yongsong Huang and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Extended data figures and tables
a, Major features and tributaries of the Ganges–Brahmaputra drainage basin. The background topographic image is from GeoMapApp (http://www.geomapapp.org). b, Morphology of the Bengal Fan. Sediment is dominantly delivered via turbidity currents that travel along the single-channel channel-levee system. Red circles show sediment cores used here. c, A Parasound seismic-reflection profile crossing cores SO93-117KL and SO93-120KL from west to east. The upper left inset shows locations of the profile and cores with respect to the pathway of the active channel, imaged by multibeam bathymetry. The upper right inset shows Parasound data around core SO93-118 KL. Figure parts are modified from ref. 6, and details of the sediment fan system are described in ref. 55.
a–c, Age models for cores SO93-117KL (a; number of dated samples, n = 3), SO93-118KL (b; n = 10) and SO93-120KL (c; n = 12, derived through interpolation between calibrated 14C ages (Supplementary Table 1) and extrapolation to core tops and bottoms. Box widths represent sample depth intervals within cores; box heights represent calibrated age errors. Figure updated from ref. 6.
a, Radioisotopic compositions of bulk BOC and individual fatty-acid (FA) homologues (n = 47). Vertical error bars indicate propagated measurement uncertainties. b, Comparison between reservoir-age offset (as given by the difference between organic-matter and deposition age, in 14C years) of bulk BOC and C28 plus C24–32 fatty acids (n = 9). Most values fall below the 1:1 line, reflecting the contribution of excess pre-aged organic matter to the bulk BOC pool. Error bars indicate propagated radiocarbon measurement and instrument-correction uncertainties.
a–c, Graphs show comparisons of post-glacial precipitation δDP values derived from ice-volume- and vegetation-fractionation-corrected fatty-acid δD values (more-depleted values are indicative of a stronger ISM) and the pre-ageing of organic matter (given as F14R values, in dimensionless Fm units; higher values indicate less pre-ageing). Comparisons shown are: a, bulk BOC versus δDP of C28 fatty acids (n = 30) for the comprehensive data set presented in Supplementary Table 2; b, bulk BOC versus δDP of C28 fatty acids (n = 9) for the subset of samples for which we also have compound-specific (fatty-acid) 14C data (Supplementary Table 3); and c, weighted-average F14R values of C24–32 fatty acid homologues versus weighted-average δDP values of those same C24–32 fatty acids (n = 9). Vertical error bars indicate propagated radiocarbon measurement and instrument-correction uncertainties; horizontal error bars are propagated multimeasurement standard deviation (δD) errors (see ref. 6). OC, organic carbon.
Abundance of C28 (closed circles) and C24–32 (open circles) fatty-acid homologues (n = 30) in sediments within Bengal Fan channel-levee cores since the Late Glacial (data given in Supplementary Table 4). Horizontal error bars represent depositional age uncertainties (from core-age models) and are within data points if not shown.
C28 fatty-acid abundances (Supplementary Table 4) are plotted against F14R values of bulk BOC (open circles, dashed line; n = 30) and of C28 fatty acids (closed circles, solid line; n = 9). Vertical error bars indicate propagated radiocarbon measurement and instrument-correction uncertainties.
Extended Data Fig. 7 Correlation between organic-matter age structure and proxies for sediment and organic-matter composition.
a, b, Bulk BOC F14R values are plotted against: a, bulk sediment TOC values, and b, sediment Al/Si values, for all samples used herein for which both data sets exist (n = 116 and n = 50, respectively). Al/Si values in b are from refs. 6,50. Vertical error bars indicate propagated radiocarbon measurement and instrument-correction uncertainties.
Compilation of new and published radiocarbon age-dating results from planktonic foraminifera collected from Bengal Fan cores SO93- 117KL, 118KL, and 120KL, used in derivation of core age-depth models.
Results of radiocarbon analyses of bulk organic carbon (OC) and calculated reservoir age offset (R) and relative reservoir enrichment (F14R) values of the associated bulk biospheric organic carbon (BOC) and millennial component of that BOC in samples from Bengal Fan cores SO93- 117KL, 118KL, and 120KL.
Results of radiocarbon analyses of individual fatty acid homologs isolated from sediments in Bengal Fan cores SO93- 117KL, 118KL, and 120KL, and associated calculated reservoir age offset (R) and relative reservoir enrichment (F14R) values of the both the individual homologs and the subset of those cycled on millennial timescales.
Abundance of individual fatty acid homologs isolated from sediments in Bengal Fan cores SO93- 117KL, 118KL, and 120KL.
About this article
Cite this article
Hein, C.J., Usman, M., Eglinton, T.I. et al. Millennial-scale hydroclimate control of tropical soil carbon storage. Nature 581, 63–66 (2020). https://doi.org/10.1038/s41586-020-2233-9