Permafrost-carbon mobilization in Beringia caused by deglacial meltwater runoff, sea-level rise and warming
During the last deglaciation (18–8 kyr BP), shelf flooding and warming presumably led to a large-scale decomposition of permafrost soils in the mid-to-high latitudes of the Northern Hemisphere. Microbial degradation of old organic matter released from the decomposing permafrost potentially contribut...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2019-01-01
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| Series: | Environmental Research Letters |
| Subjects: | |
| Online Access: | https://doi.org/10.1088/1748-9326/ab2653 |
| _version_ | 1797747924272152576 |
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| author | Vera D Meyer Jens Hefter Peter Köhler Ralf Tiedemann Rainer Gersonde Lukas Wacker Gesine Mollenhauer |
| author_facet | Vera D Meyer Jens Hefter Peter Köhler Ralf Tiedemann Rainer Gersonde Lukas Wacker Gesine Mollenhauer |
| author_sort | Vera D Meyer |
| collection | DOAJ |
| description | During the last deglaciation (18–8 kyr BP), shelf flooding and warming presumably led to a large-scale decomposition of permafrost soils in the mid-to-high latitudes of the Northern Hemisphere. Microbial degradation of old organic matter released from the decomposing permafrost potentially contributed to the deglacial rise in atmospheric CO _2 and also to the declining atmospheric radiocarbon contents (Δ ^14 C). The significance of permafrost for the atmospheric carbon pool is not well understood as the timing of the carbon activation is poorly constrained by proxy data. Here, we trace the mobilization of organic matter from permafrost in the Pacific sector of Beringia over the last 22 kyr using mass-accumulation rates and radiocarbon signatures of terrigenous biomarkers in four sediment cores from the Bering Sea and the Northwest Pacific. We find that pronounced reworking and thus the vulnerability of old organic carbon to remineralization commenced during the early deglaciation (∼16.8 kyr BP) when meltwater runoff in the Yukon River intensified riverbank erosion of permafrost soils and fluvial discharge. Regional deglaciation in Alaska additionally mobilized significant fractions of fossil, petrogenic organic matter at this time. Permafrost decomposition across Beringia’s Pacific sector occurred in two major pulses that match the Bølling-Allerød and Preboreal warm spells and rapidly initiated within centuries. The carbon mobilization likely resulted from massive shelf flooding during meltwater pulses 1A (∼14.6 kyr BP) and 1B (∼11.5 kyr BP) followed by permafrost thaw in the hinterland. Our findings emphasize that coastal erosion was a major control to rapidly mobilize permafrost carbon along Beringia’s Pacific coast at ∼14.6 and ∼11.5 kyr BP implying that shelf flooding in Beringia may partly explain the centennial-scale rises in atmospheric CO _2 at these times. Around 16.5 kyr BP, the mobilization of old terrigenous organic matter caused by meltwater-floods may have additionally contributed to increasing CO _2 levels. |
| first_indexed | 2024-03-12T15:57:37Z |
| format | Article |
| id | doaj.art-58ef704f0aba4a87966db96e5aca2cc0 |
| institution | Directory Open Access Journal |
| issn | 1748-9326 |
| language | English |
| last_indexed | 2024-03-12T15:57:37Z |
| publishDate | 2019-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | Environmental Research Letters |
| spelling | doaj.art-58ef704f0aba4a87966db96e5aca2cc02023-08-09T14:45:59ZengIOP PublishingEnvironmental Research Letters1748-93262019-01-0114808500310.1088/1748-9326/ab2653Permafrost-carbon mobilization in Beringia caused by deglacial meltwater runoff, sea-level rise and warmingVera D Meyer0https://orcid.org/0000-0002-4958-5367Jens Hefter1https://orcid.org/0000-0002-5823-1966Peter Köhler2https://orcid.org/0000-0003-0904-8484Ralf Tiedemann3https://orcid.org/0000-0001-7211-8049Rainer Gersonde4Lukas Wacker5Gesine Mollenhauer6https://orcid.org/0000-0001-5138-564XAlfred-Wegener-Institute Helmholtz Zentrum für Polar-und Meeresforschung , D-27570 Bremerhaven, Germany; Department of Geosciences, University of Bremen , D-28359 Bremen, Germany; MARUM—Center for Marine Environmental Science, D-28359 Bremen, GermanyAlfred-Wegener-Institute Helmholtz Zentrum für Polar-und Meeresforschung , D-27570 Bremerhaven, GermanyAlfred-Wegener-Institute Helmholtz Zentrum für Polar-und Meeresforschung , D-27570 Bremerhaven, GermanyAlfred-Wegener-Institute Helmholtz Zentrum für Polar-und Meeresforschung , D-27570 Bremerhaven, GermanyAlfred-Wegener-Institute Helmholtz Zentrum für Polar-und Meeresforschung , D-27570 Bremerhaven, GermanyDepartment of Physics, Laboratory for Ion Beam Physics ETH Zürich 8093 Zürich, SwitzerlandAlfred-Wegener-Institute Helmholtz Zentrum für Polar-und Meeresforschung , D-27570 Bremerhaven, Germany; Department of Geosciences, University of Bremen , D-28359 Bremen, Germany; MARUM—Center for Marine Environmental Science, D-28359 Bremen, GermanyDuring the last deglaciation (18–8 kyr BP), shelf flooding and warming presumably led to a large-scale decomposition of permafrost soils in the mid-to-high latitudes of the Northern Hemisphere. Microbial degradation of old organic matter released from the decomposing permafrost potentially contributed to the deglacial rise in atmospheric CO _2 and also to the declining atmospheric radiocarbon contents (Δ ^14 C). The significance of permafrost for the atmospheric carbon pool is not well understood as the timing of the carbon activation is poorly constrained by proxy data. Here, we trace the mobilization of organic matter from permafrost in the Pacific sector of Beringia over the last 22 kyr using mass-accumulation rates and radiocarbon signatures of terrigenous biomarkers in four sediment cores from the Bering Sea and the Northwest Pacific. We find that pronounced reworking and thus the vulnerability of old organic carbon to remineralization commenced during the early deglaciation (∼16.8 kyr BP) when meltwater runoff in the Yukon River intensified riverbank erosion of permafrost soils and fluvial discharge. Regional deglaciation in Alaska additionally mobilized significant fractions of fossil, petrogenic organic matter at this time. Permafrost decomposition across Beringia’s Pacific sector occurred in two major pulses that match the Bølling-Allerød and Preboreal warm spells and rapidly initiated within centuries. The carbon mobilization likely resulted from massive shelf flooding during meltwater pulses 1A (∼14.6 kyr BP) and 1B (∼11.5 kyr BP) followed by permafrost thaw in the hinterland. Our findings emphasize that coastal erosion was a major control to rapidly mobilize permafrost carbon along Beringia’s Pacific coast at ∼14.6 and ∼11.5 kyr BP implying that shelf flooding in Beringia may partly explain the centennial-scale rises in atmospheric CO _2 at these times. Around 16.5 kyr BP, the mobilization of old terrigenous organic matter caused by meltwater-floods may have additionally contributed to increasing CO _2 levels.https://doi.org/10.1088/1748-9326/ab2653deglaciationpermafrost decompositionBeringiaBering Seabiomarkeratmospheric CO2 |
| spellingShingle | Vera D Meyer Jens Hefter Peter Köhler Ralf Tiedemann Rainer Gersonde Lukas Wacker Gesine Mollenhauer Permafrost-carbon mobilization in Beringia caused by deglacial meltwater runoff, sea-level rise and warming Environmental Research Letters deglaciation permafrost decomposition Beringia Bering Sea biomarker atmospheric CO2 |
| title | Permafrost-carbon mobilization in Beringia caused by deglacial meltwater runoff, sea-level rise and warming |
| title_full | Permafrost-carbon mobilization in Beringia caused by deglacial meltwater runoff, sea-level rise and warming |
| title_fullStr | Permafrost-carbon mobilization in Beringia caused by deglacial meltwater runoff, sea-level rise and warming |
| title_full_unstemmed | Permafrost-carbon mobilization in Beringia caused by deglacial meltwater runoff, sea-level rise and warming |
| title_short | Permafrost-carbon mobilization in Beringia caused by deglacial meltwater runoff, sea-level rise and warming |
| title_sort | permafrost carbon mobilization in beringia caused by deglacial meltwater runoff sea level rise and warming |
| topic | deglaciation permafrost decomposition Beringia Bering Sea biomarker atmospheric CO2 |
| url | https://doi.org/10.1088/1748-9326/ab2653 |
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