Atmospheric Δ14C in the northern and southern hemispheres over the past two millennia: Role of production rate, southern hemisphere westerly winds and ocean circulation changes
The variations of atmospheric Δ14C over the past two millennia are classically attributed to changes in its production rate in the upper atmosphere, which in turn is related to changes in solar activity and the Earth's magnetic field. However, the potential contribution of atmospheric and ocea...
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Online Access: | http://hdl.handle.net/2078.1/283695 https://doi.org/10.1016/j.quascirev.2024.108502 |
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ftunivlouvain:oai:dial.uclouvain.be:boreal:283695 2024-05-12T08:11:30+00:00 Atmospheric Δ14C in the northern and southern hemispheres over the past two millennia: Role of production rate, southern hemisphere westerly winds and ocean circulation changes Goosse, Hugues Brovkin, Victor Meissner, Katrin J. Menviel, Laurie Mouchet, Anne Muscheler, Raimund Nilsson, Andreas UCL - SST/ELI/ELIC - Earth & Climate 2024 http://hdl.handle.net/2078.1/283695 https://doi.org/10.1016/j.quascirev.2024.108502 eng eng Pergamon boreal:283695 http://hdl.handle.net/2078.1/283695 doi:10.1016/j.quascirev.2024.108502 urn:ISSN:0277-3791 urn:EISSN:1873-457X info:eu-repo/semantics/openAccess Quaternary Science Reviews, Vol. 326, p. 108502 (2024) Geology Archeology Ecology Evolution Behavior and Systematics Global and Planetary Change info:eu-repo/semantics/article 2024 ftunivlouvain https://doi.org/10.1016/j.quascirev.2024.108502 2024-04-17T16:27:27Z The variations of atmospheric Δ14C over the past two millennia are classically attributed to changes in its production rate in the upper atmosphere, which in turn is related to changes in solar activity and the Earth's magnetic field. However, the potential contribution of atmospheric and oceanic circulation changes during this period has not been precisely quantified. This has been achieved here using a coupled climate model simulating explicitly the evolution of the different carbon isotopes, driven by a new estimate of 14C production derived from 10Be measurements, and using different production rates for each hemisphere. Our results confirm that changes in global and hemispheric atmospheric Δ14C are primarily driven by changes in production rate. The very good agreement between our results and observed atmospheric Δ14C also highlights the strong consistency of current interpretations of 10Be and 14C measurements. By contrast, the interhemispheric difference in atmospheric Δ14C is controlled by changes in the intensity of southern hemisphere westerly winds (SHWW) that impact atmosphere-ocean exchange and the upwelling of 14C depleted water masses in the Southern Ocean. Changes in deep water formation in both hemispheres or open ocean polynyas in the Southern Ocean only have a small impact on atmospheric Δ14C over that period. When driven by changes in the SHWW proportional to three existing reconstructions of the Southern Annular Mode (SAM) index, the model reproduces some key characteristics of the observed interhemispheric Δ14C gradient. These include the low values in the 15th century and the peak in the 16th century, but there are also clear differences between the experiments and Δ14C observations. This suggests that while SAM reconstructions capture some robust features in the centennial variability, large uncertainties remain. Article in Journal/Newspaper Southern Ocean DIAL@UCLouvain (Université catholique de Louvain) Southern Ocean Quaternary Science Reviews 326 108502 |
institution |
Open Polar |
collection |
DIAL@UCLouvain (Université catholique de Louvain) |
op_collection_id |
ftunivlouvain |
language |
English |
topic |
Geology Archeology Ecology Evolution Behavior and Systematics Global and Planetary Change |
spellingShingle |
Geology Archeology Ecology Evolution Behavior and Systematics Global and Planetary Change Goosse, Hugues Brovkin, Victor Meissner, Katrin J. Menviel, Laurie Mouchet, Anne Muscheler, Raimund Nilsson, Andreas Atmospheric Δ14C in the northern and southern hemispheres over the past two millennia: Role of production rate, southern hemisphere westerly winds and ocean circulation changes |
topic_facet |
Geology Archeology Ecology Evolution Behavior and Systematics Global and Planetary Change |
description |
The variations of atmospheric Δ14C over the past two millennia are classically attributed to changes in its production rate in the upper atmosphere, which in turn is related to changes in solar activity and the Earth's magnetic field. However, the potential contribution of atmospheric and oceanic circulation changes during this period has not been precisely quantified. This has been achieved here using a coupled climate model simulating explicitly the evolution of the different carbon isotopes, driven by a new estimate of 14C production derived from 10Be measurements, and using different production rates for each hemisphere. Our results confirm that changes in global and hemispheric atmospheric Δ14C are primarily driven by changes in production rate. The very good agreement between our results and observed atmospheric Δ14C also highlights the strong consistency of current interpretations of 10Be and 14C measurements. By contrast, the interhemispheric difference in atmospheric Δ14C is controlled by changes in the intensity of southern hemisphere westerly winds (SHWW) that impact atmosphere-ocean exchange and the upwelling of 14C depleted water masses in the Southern Ocean. Changes in deep water formation in both hemispheres or open ocean polynyas in the Southern Ocean only have a small impact on atmospheric Δ14C over that period. When driven by changes in the SHWW proportional to three existing reconstructions of the Southern Annular Mode (SAM) index, the model reproduces some key characteristics of the observed interhemispheric Δ14C gradient. These include the low values in the 15th century and the peak in the 16th century, but there are also clear differences between the experiments and Δ14C observations. This suggests that while SAM reconstructions capture some robust features in the centennial variability, large uncertainties remain. |
author2 |
UCL - SST/ELI/ELIC - Earth & Climate |
format |
Article in Journal/Newspaper |
author |
Goosse, Hugues Brovkin, Victor Meissner, Katrin J. Menviel, Laurie Mouchet, Anne Muscheler, Raimund Nilsson, Andreas |
author_facet |
Goosse, Hugues Brovkin, Victor Meissner, Katrin J. Menviel, Laurie Mouchet, Anne Muscheler, Raimund Nilsson, Andreas |
author_sort |
Goosse, Hugues |
title |
Atmospheric Δ14C in the northern and southern hemispheres over the past two millennia: Role of production rate, southern hemisphere westerly winds and ocean circulation changes |
title_short |
Atmospheric Δ14C in the northern and southern hemispheres over the past two millennia: Role of production rate, southern hemisphere westerly winds and ocean circulation changes |
title_full |
Atmospheric Δ14C in the northern and southern hemispheres over the past two millennia: Role of production rate, southern hemisphere westerly winds and ocean circulation changes |
title_fullStr |
Atmospheric Δ14C in the northern and southern hemispheres over the past two millennia: Role of production rate, southern hemisphere westerly winds and ocean circulation changes |
title_full_unstemmed |
Atmospheric Δ14C in the northern and southern hemispheres over the past two millennia: Role of production rate, southern hemisphere westerly winds and ocean circulation changes |
title_sort |
atmospheric î”14c in the northern and southern hemispheres over the past two millennia: role of production rate, southern hemisphere westerly winds and ocean circulation changes |
publisher |
Pergamon |
publishDate |
2024 |
url |
http://hdl.handle.net/2078.1/283695 https://doi.org/10.1016/j.quascirev.2024.108502 |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
Quaternary Science Reviews, Vol. 326, p. 108502 (2024) |
op_relation |
boreal:283695 http://hdl.handle.net/2078.1/283695 doi:10.1016/j.quascirev.2024.108502 urn:ISSN:0277-3791 urn:EISSN:1873-457X |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.1016/j.quascirev.2024.108502 |
container_title |
Quaternary Science Reviews |
container_volume |
326 |
container_start_page |
108502 |
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1798855229981065216 |