Preboreal oscillation
Definition
Based on evidence from pollen, early Holocene cooling periods have been discovered already from the 1960s on. Locally, they were referred to as ‘Friesland Oscillation’ (Denmark {{Cite journal |last=Iversen |first=Johs. |date=1973-12-31 |title=Geology of Denmark III: The Development of Denmark's Nature since the Last Glacial |url=https://geusjournals.org/index.php/raekke5/article/view/7020 |journal=Danmarks Geologiske Undersøgelse V. Række |volume=7 |pages=1–126 |doi=10.34194/raekke5.v7.7020 |issn=2597-3037|doi-access=free }}), ‘Youngest Dryas’ (Germany {{Cite journal |last=Behre |first=Karl-Ernst |date=1978 |title=Die Klimaschwankungen im europäischen Präboreal |url=https://www.researchgate.net/publication/259339969 |journal=Petermans geographische Mitteilungen |volume=2 |pages=97–102}}), ‘Rammelbeek Phase’ (Netherlands {{Cite journal |last1=Bos |first1=Johanna A.A. |last2=van Geel |first2=Bas |last3=van der Plicht |first3=Johannes |last4=Bohncke |first4=Sjoerd J.P. |date=2007 |title=Preboreal climate oscillations in Europe: Wiggle-match dating and synthesis of Dutch high-resolution multi-proxy records |url=https://linkinghub.elsevier.com/retrieve/pii/S0277379107001990 |journal=Quaternary Science Reviews |language=en |volume=26 |issue=15–16 |pages=1927–1950 |doi=10.1016/j.quascirev.2006.09.012|bibcode=2007QSRv...26.1927B }}), and ‘Piottino Oscillation’ (Switzerland {{Cite journal |last=Zoller |first=H. |date=1960 |title=Pollenanalytische Untersuchungen zur Vegetationsgeschichte der insubrischen Schweiz. |journal=Denkschriften der Schweizerischen Naturforschenden Gesellschaft |volume=83 |pages=45–156}}). The term "preboreal oscillation" was derived from attempts to synchronize these events.{{Cite journal |last1=Lowe |first1=J. John |last2=Ammann |first2=B. |last3=Birks |first3=H. H. |last4=Björck |first4=S. |last5=Coope |first5=G. R. |last6=Cwynar |first6=L. |last7=de Beaulieu |first7=J.-L. |last8=Mott |first8=R. J. |last9=Peteet |first9=D. M. |last10=Walker |first10=M. J. C. |date=1994 |title=Climatic changes in areas adjacent to the North Atlantic during the last glacial-interglacial transition (14-9 ka BP): A contribution to IGCP-253 |url=https://onlinelibrary.wiley.com/doi/10.1002/jqs.3390090215 |journal=Journal of Quaternary Science |language=en |volume=9 |issue=2 |pages=185–198 |doi=10.1002/jqs.3390090215|bibcode=1994JQS.....9..185L |url-access=subscription }}{{Cite journal |last1=Björck |first1=Svante |last2=Kromer |first2=Bernd |last3=Johnsen |first3=Sigfus |last4=Bennike |first4=Ole |last5=Hammarlund |first5=Dan |last6=Lemdahl |first6=Geoffrey |last7=Possnert |first7=Göran |last8=Rasmussen |first8=Tine Lander |last9=Wohlfarth |first9=Barbara |last10=Hammer |first10=Claus Uffe |last11=Spurk |first11=Marco |date=1996 |title=Synchronized Terrestrial Atmospheric Deglacial Records Around the North Atlantic |url=https://www.science.org/doi/10.1126/science.274.5290.1155 |journal=Science |language=en |volume=274 |issue=5290 |pages=1155–1160 |doi=10.1126/science.274.5290.1155 |pmid=8895457 |bibcode=1996Sci...274.1155B |s2cid=45121979 |issn=0036-8075|url-access=subscription }}
Dating
The Greenland ice cores record a distinct decline in stable oxygen isotope data dated to 11 650–11 270 ice layer a BP (11 700–11 320 b2k) with the coldest part between 11 470 and 11 350 ice layer a BP (11 520–11 400 b2k) labelled as the ‘11.4 ka event’.{{Cite journal |last1=Rasmussen |first1=Sune O. |last2=Bigler |first2=Matthias |last3=Blockley |first3=Simon P. |last4=Blunier |first4=Thomas |last5=Buchardt |first5=Susanne L. |last6=Clausen |first6=Henrik B. |last7=Cvijanovic |first7=Ivana |last8=Dahl-Jensen |first8=Dorthe |last9=Johnsen |first9=Sigfus J. |last10=Fischer |first10=Hubertus |last11=Gkinis |first11=Vasileios |last12=Guillevic |first12=Myriam |last13=Hoek |first13=Wim Z. |last14=Lowe |first14=J. John |last15=Pedro |first15=Joel B. |date=2014 |title=A stratigraphic framework for abrupt climatic changes during the Last Glacial period based on three synchronized Greenland ice-core records: refining and extending the INTIMATE event stratigraphy |url=https://www.researchgate.net/publication/266562847 |journal=Quaternary Science Reviews |language=en |volume=106 |pages=14–28 |doi=10.1016/j.quascirev.2014.09.007|bibcode=2014QSRv..106...14R |s2cid=55614771 |doi-access=free |hdl=2160/30436 |hdl-access=free }}
In lake sedimentary records, the exact timing and duration of the PBO remain uncertain because of dating uncertainties due to two early Holocene radiocarbon plateau and unclear proxy evidence. {{Cite journal |last1=Björck |first1=S. |last2=Rundgren |first2=M. |last3=Ingólfsson |first3=Ó. |last4=Funder |first4=S. |date=1997 |title=The Preboreal oscillation around the Nordic Seas: terrestrial and lacustrine responses |url=https://doi.org/10.1002/(SICI)1099-1417(199711/12)12:6<455::AID-JQS316>3.0.CO;2-S |journal=Journal of Quaternary Science |volume=12 |issue=6 |pages=455–465 |doi=10.1002/(SICI)1099-1417(199711/12)12:6<455::AID-JQS316>3.0.CO;2-S|bibcode=1997JQS....12..455B }}{{Cite journal |last1=Hoek |first1=Wim Z. |last2=Bos |first2=Johanna A.A. |date=2007 |title=Early Holocene climate oscillations—causes and consequences |url=https://linkinghub.elsevier.com/retrieve/pii/S0277379107001679 |journal=Quaternary Science Reviews |language=en |volume=26 |issue=15–16 |pages=1901–1906 |doi=10.1016/j.quascirev.2007.06.008|bibcode=2007QSRv...26.1901H |url-access=subscription }} Two ash layers derived from volcanic eruptions are frequently used as time markers for the PBO: the Askja-S and Hässeldalen tephras shortly before and after the event. {{Cite journal |last1=Wohlfarth |first1=B. |last2=Blaauw |first2=M. |last3=Davies |first3=S. M. |last4=Andersson |first4=M. |last5=Wastegård |first5=S. |last6=Hormes |first6=A. |last7=Possnert |first7=G. |date=2006 |title=Constraining the age of Lateglacial and early Holocene pollen zones and tephra horizons in southern Sweden with Bayesian probability methods. |journal=Journal of Quaternary Science |volume=21 |issue=4 |pages=321–334 |doi=10.1002/jqs.996|bibcode=2006JQS....21..321W |s2cid=67800522 |url=https://pure.qub.ac.uk/ws/files/2788037/Wohlfarth_et_al_2006_JQS.pdf }} The ages of these layers were constrained to 11.228 ± 226 cal a BP and 11.380 ± 216 cal a BP, framing the cold event to a maximum duration of 152 +11/-8 years by varve counting. {{Cite journal |last1=Ott |first1=Florian |last2=Wulf |first2=Sabine |last3=Serb |first3=Johanna |last4=Słowiński |first4=Michał |last5=Obremska |first5=Milena |last6=Tjallingii |first6=Rik |last7=Błaszkiewicz |first7=Mirosław |last8=Brauer |first8=Achim |date=2016 |title=Constraining the time span between the Early Holocene Hässeldalen and Askja-S Tephras through varve counting in the Lake Czechowskie sediment record, Poland: VARVE COUNTING BETWEEN THE HÄSSELDALEN AND AKSJA-S TEPHRA |url=https://onlinelibrary.wiley.com/doi/10.1002/jqs.2844 |journal=Journal of Quaternary Science |language=en |volume=31 |issue=2 |pages=103–113 |doi=10.1002/jqs.2844|s2cid=131161085 }}