Intensification of Southern Hemisphere westerly winds 2000–1000 years ago: evidence from the subantarctic Campbell and Auckland Islands (52–50°S)

Turney, Chris S. M.; McGlone, Matt S.; Palmer, Jonathan; Fogwill, Christopher J.; Hogg, Alan G.; Thomas, Zoë; Lipson, Mathew; Wilmshurst, Janet M.; Fenwick, Pavla; Jones, Richard T.; Hines, Benjamin R.; Clark, Graeme F.

doi:10.1002/jqs.2828

Cited by 18 publications

(15 citation statements)

References 44 publications

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“…BP and/or lay close to the latitude of the Falkland Islands -at least within the South American sector and possibly hemispheric-wide (Turney et al, 2016) (Fig. 7).…”

Section: Resultsmentioning

confidence: 78%

A 250-year periodicity in Southern Hemisphere westerly winds over the last 2600 years

et al. 2016

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Abstract. Southern Hemisphere westerly airflow has a significant influence on the ocean-atmosphere system of the mid-to high latitudes with potentially global climate implications. Unfortunately, historic observations only extend back to the late 19th century, limiting our understanding of multi-decadal to centennial change. Here we present a highly resolved (30-year) record of past westerly wind strength from a Falkland Islands peat sequence spanning the last 2600 years. Situated within the core latitude of Southern Hemisphere westerly airflow (the so-called furious fifties), we identify highly variable changes in exotic pollen and charcoal derived from South America which can be used to inform on past westerly air strength. We find a period of high charcoal content between 2000 and 1000 cal. years BP, associated with increased burning in Patagonia, most probably as a result of higher temperatures and stronger westerly airflow. Spectral analysis of the charcoal record identifies a pervasive ca. 250-year periodicity that is coherent with radiocarbon production rates, suggesting that solar variability has a modulating influence on Southern Hemisphere westerly airflow. Our results have important implications for understanding global climate change through the late Holocene.

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“…BP and/or lay close to the latitude of the Falkland Islands -at least within the South American sector and possibly hemispheric-wide (Turney et al, 2016) (Fig. 7).…”

Section: Resultsmentioning

confidence: 78%

A 250-year periodicity in Southern Hemisphere westerly winds over the last 2600 years

et al. 2016

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“…Our results imply that the central Southern Hemisphere westerlies were particularly strong between 2000 and 1000 cal. BP and/or lay close to the latitude of the Falkland Islands -at least within the South American sector and possibly hemispheric-wide (Turney et al, 2016) (Fig. 7).…”

Section: Parameter Marine98 Marine04mentioning

confidence: 78%

A 250 year periodicity in Southern Hemisphere westerly winds over the last 2600 years

Turney¹,

Jones²,

Fogwill³

et al. 2015

Preprint

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Abstract. Southern Hemisphere westerly airflow has a significant influence on the ocean–atmosphere system of the mid- to high-latitudes with potentially global climate implications. Unfortunately historic observations only extend back to the late nineteenth century, limiting our understanding of multi-decadal to centennial change. Here we present a highly resolved (30 yr) record of past westerly air strength from a Falkland Islands peat sequence spanning the last 2600 years. Situated under the core latitude of Southern Hemisphere westerly airflow, we identify highly variable changes in exotic pollen derived from South America which can be used to inform on past westerly air strength and location. The results indicate enhanced airflow over the Falklands between 2000 and 1000 cal. yr BP, and associated with increased burning, most probably as a result of higher temperatures and/or reduced precipitation, comparable to records in South America. Spectral analysis of the charcoal record identifies a 250 year periodicity within the data, suggesting solar variability has a modulating influence on Southern Hemisphere westerly airflow with potentially important implications for understanding global climate change through the late Holocene.

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“…However, no substantive change in Northern Hemisphere 14 C is recorded across 1860 C.E., with relatively young ages across this period (Figure ). Importantly, paleoreconstructions indicate that alongside a warming climate post‐LIA [ PAGES 2 k Consortium , ], there were highly variable changes in westerly airflow across the midlatitudes of the Southern Hemisphere [ Lamy et al ., ; McGlone et al ., ; Turney et al ., , ], suggesting that the Southern Ocean sea‐air flux of 14 CO 2 may play a role.…”

Section: Resultsmentioning

confidence: 99%

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

Turney

Palmer

Hogg

et al. 2016

Global Biogeochemical Cycles

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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.

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Intensification of Southern Hemisphere westerly winds 2000–1000 years ago: evidence from the subantarctic Campbell and Auckland Islands (52–50°S)

Cited by 18 publications

References 44 publications

A 250-year periodicity in Southern Hemisphere westerly winds over the last 2600 years

A 250-year periodicity in Southern Hemisphere westerly winds over the last 2600 years

A 250 year periodicity in Southern Hemisphere westerly winds over the last 2600 years

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

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Intensification of Southern Hemisphere westerly winds 2000–1000 years ago: evidence from the subantarctic Campbell and Auckland Islands (52–50°S)

Cited by 18 publications

References 44 publications

A 250-year periodicity in Southern Hemisphere westerly winds over the last 2600 years

A 250-year periodicity in Southern Hemisphere westerly winds over the last 2600 years

A 250 year periodicity in Southern Hemisphere westerly winds over the last 2600 years

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

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