Multidecadal variations in Southern Hemisphere atmospheric 14C: Evidence against a Southern Ocean sink at the end of the Little Ice Age CO2 anomaly

C.S.M. Turney, J. Palmer, A. Hogg, C.J. Fogwill, R.T. Jones, C. Bronk Ramsey, P. Fenwick, Pauline Grierson, J. Wilmshurst, Alison O'Donnell, Z.A. Thomas, M. Lipson

Research output: Contribution to journalArticle

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Abstract

©2016. American Geophysical Union. All Rights Reserved. Northern Hemisphere-wide cooling during the Little Ice Age (LIA; 1650-1775 Common Era, C.E.) was associated with a ~5 ppmv decrease in atmospheric carbon dioxide. Changes in terrestrial and ocean carbon reservoirs have been postulated as possible drivers of this relatively large shift in atmospheric CO2, potentially providing insights into the mechanisms and sensitivity of the global carbon cycle. Here we report decadally resolved radiocarbon (14C) levels in a network of tree-ring series spanning 1700-1950 C.E. located along the northern boundary of, and within, the Southern Ocean. We observe regional dilutions in atmospheric radiocarbon (relative to the Northern Hemisphere) associated with upwelling of 14CO2-depleted abyssal waters. We find the interhemispheric 14C offset approaches zero during increasing global atmospheric CO2 at the end of the LIA, with reduced ventilation in the Southern Ocean and a Northern Hemisphere source of old carbon (most probably originating from deep Arctic peat layers). The coincidence of the atmospheric CO2 increase and reduction in the interhemispheric 14C offset imply a common climate control. Possible mechanisms of synchronous change in the high latitudes of both hemispheres are discussed.
Original languageEnglish
Pages (from-to)211-218
JournalGlobal Biogeochemical Cycles
Volume30
Issue number2
DOIs
Publication statusPublished - 18 Feb 2016

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Little Ice Age
Ice
Southern Hemisphere
Northern Hemisphere
Carbon
anomaly
ocean
Climate control
Peat
carbon
tree ring
carbon cycle
Carbon Dioxide
Dilution
Ventilation
ventilation
peat
upwelling
dilution
carbon dioxide

Cite this

Turney, C.S.M. ; Palmer, J. ; Hogg, A. ; Fogwill, C.J. ; Jones, R.T. ; Bronk Ramsey, C. ; Fenwick, P. ; Grierson, Pauline ; Wilmshurst, J. ; O'Donnell, Alison ; Thomas, Z.A. ; Lipson, M. / Multidecadal variations in Southern Hemisphere atmospheric 14C: Evidence against a Southern Ocean sink at the end of the Little Ice Age CO2 anomaly. In: Global Biogeochemical Cycles. 2016 ; Vol. 30, No. 2. pp. 211-218.
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Turney, CSM, Palmer, J, Hogg, A, Fogwill, CJ, Jones, RT, Bronk Ramsey, C, Fenwick, P, Grierson, P, Wilmshurst, J, O'Donnell, A, Thomas, ZA & Lipson, M 2016, 'Multidecadal variations in Southern Hemisphere atmospheric 14C: Evidence against a Southern Ocean sink at the end of the Little Ice Age CO2 anomaly' Global Biogeochemical Cycles, vol. 30, no. 2, pp. 211-218. https://doi.org/10.1002/2015GB005257

Multidecadal variations in Southern Hemisphere atmospheric 14C: Evidence against a Southern Ocean sink at the end of the Little Ice Age CO2 anomaly. / Turney, C.S.M.; Palmer, J.; Hogg, A.; Fogwill, C.J.; Jones, R.T.; Bronk Ramsey, C.; Fenwick, P.; Grierson, Pauline; Wilmshurst, J.; O'Donnell, Alison; Thomas, Z.A.; Lipson, M.

In: Global Biogeochemical Cycles, Vol. 30, No. 2, 18.02.2016, p. 211-218.

Research output: Contribution to journalArticle

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T1 - Multidecadal variations in Southern Hemisphere atmospheric 14C: Evidence against a Southern Ocean sink at the end of the Little Ice Age CO2 anomaly

AU - Turney, C.S.M.

AU - Palmer, J.

AU - Hogg, A.

AU - Fogwill, C.J.

AU - Jones, R.T.

AU - Bronk Ramsey, C.

AU - Fenwick, P.

AU - Grierson, Pauline

AU - Wilmshurst, J.

AU - O'Donnell, Alison

AU - Thomas, Z.A.

AU - Lipson, M.

PY - 2016/2/18

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N2 - ©2016. American Geophysical Union. All Rights Reserved. Northern Hemisphere-wide cooling during the Little Ice Age (LIA; 1650-1775 Common Era, C.E.) was associated with a ~5 ppmv decrease in atmospheric carbon dioxide. Changes in terrestrial and ocean carbon reservoirs have been postulated as possible drivers of this relatively large shift in atmospheric CO2, potentially providing insights into the mechanisms and sensitivity of the global carbon cycle. Here we report decadally resolved radiocarbon (14C) levels in a network of tree-ring series spanning 1700-1950 C.E. located along the northern boundary of, and within, the Southern Ocean. We observe regional dilutions in atmospheric radiocarbon (relative to the Northern Hemisphere) associated with upwelling of 14CO2-depleted abyssal waters. We find the interhemispheric 14C offset approaches zero during increasing global atmospheric CO2 at the end of the LIA, with reduced ventilation in the Southern Ocean and a Northern Hemisphere source of old carbon (most probably originating from deep Arctic peat layers). The coincidence of the atmospheric CO2 increase and reduction in the interhemispheric 14C offset imply a common climate control. Possible mechanisms of synchronous change in the high latitudes of both hemispheres are discussed.

AB - ©2016. American Geophysical Union. All Rights Reserved. Northern Hemisphere-wide cooling during the Little Ice Age (LIA; 1650-1775 Common Era, C.E.) was associated with a ~5 ppmv decrease in atmospheric carbon dioxide. Changes in terrestrial and ocean carbon reservoirs have been postulated as possible drivers of this relatively large shift in atmospheric CO2, potentially providing insights into the mechanisms and sensitivity of the global carbon cycle. Here we report decadally resolved radiocarbon (14C) levels in a network of tree-ring series spanning 1700-1950 C.E. located along the northern boundary of, and within, the Southern Ocean. We observe regional dilutions in atmospheric radiocarbon (relative to the Northern Hemisphere) associated with upwelling of 14CO2-depleted abyssal waters. We find the interhemispheric 14C offset approaches zero during increasing global atmospheric CO2 at the end of the LIA, with reduced ventilation in the Southern Ocean and a Northern Hemisphere source of old carbon (most probably originating from deep Arctic peat layers). The coincidence of the atmospheric CO2 increase and reduction in the interhemispheric 14C offset imply a common climate control. Possible mechanisms of synchronous change in the high latitudes of both hemispheres are discussed.

U2 - 10.1002/2015GB005257

DO - 10.1002/2015GB005257

M3 - Article

VL - 30

SP - 211

EP - 218

JO - Global Biogeochemical Cycles

JF - Global Biogeochemical Cycles

SN - 0886-6236

IS - 2

ER -