Proxy benchmarks for intercomparison of 8.2 ka simulations

Morrill, C.; Anderson, David M.; Bauer, B. A.; Buckner, Randy L.; Gille, E. P.; Gross, Wendy S.; Hartman, Michael; Shah, A.

doi:10.5194/cp-9-423-2013

Cited by 70 publications

(109 citation statements)

References 64 publications

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“…Records of the 8.2 ka event at lower latitudes help to delineate the response of near-modern climate to this perturbation. Although documenting the spatial extent and duration of the 8.2 ka event from proxy records outside of Greenland has been challenging due to the brevity of the event 6 , mounting evidence from mid-latitude and tropical records suggests cooling in the North Atlantic region 7 , and a southward shift of the Intertropical Convergence Zone (ITCZ) and associated precipitation bands 8 . In British Columbia, lake sediments suggest glacial advance, consistent with a cooler and/or wetter climate 9 , and marine sediments indicate decreased sea surface temperatures along the northern California coast 10 .…”

Section: Introductionmentioning

confidence: 99%

Climate response to the 8.2 ka event in coastal California

Oster

Sharp

Covey

et al. 2017

Sci Rep

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A fast-growing stalagmite from the central California coast provides a high-resolution record of climatic changes synchronous with global perturbations resulting from the catastrophic drainage of proglacial Lake Agassiz at ca. 8.2 ka. High frequency, large amplitude variations in carbon isotopes during the 8.2 ka event, coupled with pulsed increases in phosphorus concentrations, indicate more frequent or intense winter storms on the California coast. Decreased magnesium-calcium ratios point toward a sustained increase in effective moisture during the event, however the magnitude of change in Mg/Ca suggests this event was not as pronounced on the western North American coast as anomalies seen in the high northern latitudes and monsoon-influenced areas. Nevertheless, shifts in the White Moon Cave record that are synchronous within age uncertainties with cooling of Greenland, and changes in global monsoon systems, suggest rapid changes in atmospheric circulation occurred in response to freshwater input and associated cooling in the North Atlantic region. Our record is consistent with intensification of the Pacific winter storm track in response to North Atlantic freshwater forcing, a mechanism suggested by simulations of the last deglaciation, and indicates this intensification led to increases in precipitation and infiltration along the California coast during the Holocene.

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Section: Introductionmentioning

confidence: 99%

Climate response to the 8.2 ka event in coastal California

Oster

Sharp

Covey

et al. 2017

Sci Rep

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“…Several other proxy records of similar length are available for comparison in the region of the SWM and the East Asian Monsoon (EAM). Oxygen isotope records from radiometrically-dated speleothems (Cheng et al, 2009;Liu et al, 2013;Fleitmann et al, 2003Fleitmann et al, , 2004Fleitmann et al, , 2007Morrill et al, 2013aMorrill et al, , 2013b show a general unidirectional decrease in δ 18 O since about 8000 yr BP ( The speoleothem records also show a trough in the δ 18 O between 8500 and 8000 yr BP., interpreted in part as a decrease in monsoon intensity beginning at 8200 yr BP and lasting 100 to 150 yr. An event close to this time is present in the Kukkal sediments at an interpolated age of 8700 yr BP, where it is marked by the replacement of savanna vegetation by grassland assemblage, and inflections in the curves of major oxide abundances. Given the uncertainties of the age interpolation, the proxy records may all be recording the same event.…”

Section: Regional and Global Correlationsmentioning

confidence: 99%

Early-Holocene to present palaeoenvironmental shifts and short climate events from the tropical wetland and lake sediments, Kukkal Lake, Southern India: Geochemistry and palynology

et al. 2016

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The Kukkal basin, Tamil Nadu, India, receives most of its rain from the southwest monsoon. A sediment core from Kukkal Lake, preserves a continuous sediment record from the Early Holocene to present (9000 yr BP to present). The present lake is artificial, situated at an elevation of ~1887 m a.s.l.,, in a small basin that appears to have alternated between a and wetland depositional environment. Climate proxies, including sediment texture, TOC, Total Nitrogen (TN), C/N, pollen and geochemical composition indicate a steady progression to wetter conditions, with two stepwise changes at about 8000, and between 3200 and 1800 yr BP. The change at 8000 yr BP appears to correspond to a brief (100-150 yr) dry spell to about 8000 yr BP, followed by grassland with palms, the appearance of ferns just prior to 3200 yr BP, and the establishment of forest between 3200 and about 1800 yr BP.

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“…same direction as a MAAT reduction. None of these two scenarios can a priori be excluded or proven because robust quantitative precipitation reconstructions on a seasonal base for the time interval around 8.2 ka BP are still lacking for the European Alps (Morrill et al, 2013a). However, there is indication from proxy data and model simulations for a coincidence of cool phases and increased summer precipitation in Central Europe during the last 400 years (Wegmann et al, 2014), which, if transferred into the past, would support an underestimation of the temperature changes inferred from the Mondsee d…”

mentioning

confidence: 99%

Evidence for higher-than-average air temperatures after the 8.2 ka event provided by a Central European δ18O record

Andersen

Lauterbach

Erlenkeuser

et al. 2017

Quaternary Science Reviews

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a b s t r a c tThe so-called 8.2 ka event represents one of the most prominent cold climate anomalies during the Holocene warm period. Accordingly, several studies have addressed its trigger mechanisms, absolute dating and regional characteristics so far. However, knowledge about subsequent climate recovery is still limited although this might be essential for the understanding of rapid climatic changes. Here we present a new sub-decadally resolved and precisely dated oxygen isotope (d 18 O) record for the interval between 7.7 and 8.7 ka BP (10 3 calendar years before AD 1950), derived from the calcareous valves of benthic ostracods preserved in the varved lake sediments of pre-Alpine Mondsee (Austria). Besides a clear reflection of the 8.2 ka event, showing a good agreement in timing, duration and magnitude with other regional stable isotope records, the high-resolution Mondsee lake sediment record provides evidence for a 75-year-long interval of higher-than-average d 18O values directly after the 8.2 ka event, possibly reflecting increased air temperatures in Central Europe. This observation is consistent with evidence from other proxy records in the North Atlantic realm, thus most probably reflecting a hemispheric-scale climate signal rather than a local phenomenon. As a possible trigger we suggest an enhanced resumption of the Atlantic meridional overturning circulation (AMOC), supporting assumptions from climate model simulations.

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Proxy benchmarks for intercomparison of 8.2 ka simulations

Cited by 70 publications

References 64 publications

Climate response to the 8.2 ka event in coastal California

Climate response to the 8.2 ka event in coastal California

Early-Holocene to present palaeoenvironmental shifts and short climate events from the tropical wetland and lake sediments, Kukkal Lake, Southern India: Geochemistry and palynology

Evidence for higher-than-average air temperatures after the 8.2 ka event provided by a Central European δ18O record

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