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  • 1
    Publication Date: 2021-02-08
    Description: The mobilization of glacial permafrost carbon during the last glacial–interglacial transition has been suggested by indirect evidence to be an additional and significant source of greenhouse gases to the atmosphere, especially at times of rapid sea-level rise. Here we present the first direct evidence for the release of ancient carbon from degrading permafrost in East Asia during the last 17 kyrs, using biomarkers and radiocarbon dating of terrigenous material found in two sediment cores from the Okhotsk Sea. Upscaling our results to the whole Arctic shelf area, we show by carbon cycle simulations that deglacial permafrost-carbon release through sea-level rise likely contributed significantly to the changes in atmospheric CO2 around 14.6 and 11.5 kyrs BP.
    Type: Article , PeerReviewed
    Format: text
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  • 2
    Publication Date: 2022-01-31
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
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  • 3
    Publication Date: 2024-02-07
    Description: The changes in atmospheric pCO2 provide evidence for the release of large amounts of ancient carbon during the last deglaciation. However, the sources and mechanisms that contributed to this process remain unresolved. Here, we present evidence for substantial ancient terrestrial carbon remobilization in the Canadian Arctic following the Laurentide Ice Sheet retreat. Glacial-retreat-induced physical erosion of bedrock has mobilized petrogenic carbon, as revealed by sedimentary records of radiocarbon dates and thermal maturity of organic carbon from the Canadian Beaufort Sea. Additionally, coastal erosion during the meltwater pulses 1a and 1b has remobilized pre-aged carbon from permafrost. Assuming extensive petrogenic organic carbon oxidation during the glacial retreat, a model-based assessment suggests that the combined processes have contributed 12 ppm to the deglacial CO2 rise. Our findings suggest potentially positive climate feedback of ice-sheet retreat by accelerating terrestrial organic carbon remobilization and subsequent oxidation during the glacial-interglacial transition.
    Type: Article , PeerReviewed
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  • 4
    Publication Date: 2024-02-07
    Description: Rock-derived or petrogenic organic carbon has traditionally been regarded as being non-bioavailable and bypassing the active carbon cycle when eroded. However, it has become apparent that this organic carbon might not be so inert, especially in fjord systems where petrogenic organic carbon influxes can be high, making its degradation another potential source of greenhouse gas emissions. The extent to which subsurface micro-organisms use this organic carbon is not well constrained, despite its potential impacts on global carbon cycling. Here, we performed compound-specific radiocarbon analyses on intact polar lipid–fatty acids of live micro-organisms from marine sediments in Hornsund Fjord, Svalbard. By this means, we estimate that local bacterial communities utilize between 5 ± 2% and 55 ± 6% (average of 25 ± 16%) of petrogenic organic carbon for their biosynthesis, providing evidence for the important role of petrogenic organic carbon as a substrate after sediment redeposition. We hypothesize that the lack of sufficient recently synthesized organic carbon from primary production forces micro-organisms into utilization of petrogenic organic carbon as an alternative energy source. The input of petrogenic organic carbon to marine sediments and subsequent utilization by subsurface micro-organisms represents a natural source of fossil greenhouse gas emissions over geological timescales.
    Type: Article , PeerReviewed
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  • 5
    Publication Date: 2022-05-26
    Description: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Waelbroeck, C., Lougheed, B. C., Riveiros, N. V., Missiaen, L., Pedro, J., Dokken, T., Hajdas, I., Wacker, L., Abbott, P., Dumoulin, J., Thil, F., Eynaud, F., Rossignol, L., Fersi, W., Albuquerque, A. L., Arz, H., Austin, W. E. N., Came, R., Carlson, A. E., Collins, J. A., Dennielou, B., Desprat, S., Dickson, A., Elliot, M., Farmer, C., Giraudeau, J., Gottschalk, J., Henderiks, J., Hughen, K., Jung, S., Knutz, P., Lebreiro, S., Lund, D. C., Lynch-Stieglitz, J., Malaize, B., Marchitto, T., Martinez-Mendez, G., Mollenhauer, G., Naughton, F., Nave, S., Nuernberg, D., Oppo, D., Peck, V., Peeters, F. J. C., Penaud, A., Portilho-Ramos, R. d. C., Repschlaeger, J., Roberts, J., Ruehlemann, C., Salgueiro, E., Goni, M. F. S., Schonfeld, J., Scussolini, P., Skinner, L. C., Skonieczny, C., Thornalley, D., Toucanne, S., Van Rooij, D., Vidal, L., Voelker, A. H. L., Wary, M., Weldeab, S., & Ziegler, M. Consistently dated Atlantic sediment cores over the last 40 thousand years. Scientific Data, 6, (2019): 165, doi:10.1038/s41597-019-0173-8.
    Description: Rapid changes in ocean circulation and climate have been observed in marine-sediment and ice cores over the last glacial period and deglaciation, highlighting the non-linear character of the climate system and underlining the possibility of rapid climate shifts in response to anthropogenic greenhouse gas forcing. To date, these rapid changes in climate and ocean circulation are still not fully explained. One obstacle hindering progress in our understanding of the interactions between past ocean circulation and climate changes is the difficulty of accurately dating marine cores. Here, we present a set of 92 marine sediment cores from the Atlantic Ocean for which we have established age-depth models that are consistent with the Greenland GICC05 ice core chronology, and computed the associated dating uncertainties, using a new deposition modeling technique. This is the first set of consistently dated marine sediment cores enabling paleoclimate scientists to evaluate leads/lags between circulation and climate changes over vast regions of the Atlantic Ocean. Moreover, this data set is of direct use in paleoclimate modeling studies.
    Description: The research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Program (FP7/2007-2013 Grant agreement n° 339108). New 14C dates for cores EW9209-1JPC and V29-202 were funded by NSF OCE grants to DWO. FN, ES and AV acknowledge FCT funding support through project UID/Multi/04326/2019. We thank T. Garlan and P. Guyomard for having given us access to cores from the Service Hydrographique et Océanographique de la Marine. We acknowledge N. Smialkowski for help with formatting the data into text files, and L. Mauclair, L. Leroy and G. Isguder for the picking of numerous foraminifer samples for radiocarbon dating. We are grateful to S. Obrochta, E. Cortijo, E. Michel, F. Bassinot, J.C. Duplessy, and L. Labeyrie for advice and fruitful discussions. This paper is LSCE contribution 6572.
    Repository Name: Woods Hole Open Access Server
    Type: Article
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