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The Preboreal Climate Reversal and a Subsequent Solar-Forced Climate Shift

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The Preboreal Climate Reversal and a Subsequent Solar-Forced Climate Shift The Preboreal climate reversal and a subsequent solar-forced climate shift Van Der Plicht, J., Van Geel, B., Bohncke, S. J. P., Bos, J. A. A., Blaauw, M., Speranza, A. O. M., Muscheler, R., & Bjorck, S. (2004). The Preboreal climate reversal and a subsequent solar-forced climate shift. Journal of Quaternary Science, 19(3), 263-269. https://doi.org/10.1002/jqs.835 Published in: Journal of Quaternary Science Document Version: Publisher's PDF, also known as Version of record Queen's University Belfast - Research Portal: Link to publication record in Queen's University Belfast Research Portal General rights Copyright for the publications made accessible via the Queen's University Belfast Research Portal is retained by the author(s) and / or other copyright owners and it is a condition of accessing these publications that users recognise and abide by the legal requirements associated with these rights. Take down policy The Research Portal is Queen's institutional repository that provides access to Queen's research output. Every effort has been made to ensure that content in the Research Portal does not infringe any person's rights, or applicable UK laws. If you discover content in the Research Portal that you believe breaches copyright or violates any law, please contact [email protected]. Download date:27. Sep. 2021 JOURNAL OF QUATERNARY SCIENCE (2004) 19(3) 263–269 Copyright ß 2004 John Wiley & Sons, Ltd. Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jqs.835 The Preboreal climate reversal and a subsequent solar-forced climate shift J. VAN DER PLICHT,1* B. VAN GEEL,2 S. J. P. BOHNCKE,3 J. A. A. BOS,2 M. BLAAUW,2 A. O. M. SPERANZA,2 R. MUSCHELER4 and S. BJO¨ RCK4 1 Centre for Isotope Research, Radiocarbon Laboratory, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands 2 Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Kruislaan 318, 1098 SM Amsterdam, The Netherlands 3 Department of Quaternary Geology and Geomorphology, Free University, de Boelelaan 1085, 1081 HV Amsterdam, The Netherlands 4 Department of Geology, Quaternary Geology, Lund University, Tornava¨gen 13, 22363 Lund, Sweden van der Plicht, J., van Geel, B., Bohncke, S. J. P., Bos, J. A. A., Blaauw, M., Speranza, A. O. M., Muscheler, R. and Bjo¨rck, S. 2004. The Preboreal climate reversal and a subsequent solar-forced climate shift. J. Quaternary Sci., Vol. 19 pp. 263–269. ISSN 0267-8179. Received 23 January 2003; Revised 4 November 2003; Accepted 7 December 2003 ABSTRACT: Accurate chronologies are essential for linking palaeoclimate archives. Carbon-14 wiggle-match dating was used to produce an accurate chronology for part of an early Holocene peat sequence from the Borchert (The Netherlands). Following the Younger Dryas–Preboreal transition, two climatic shifts could be inferred. Around 11 400 cal. yr BP the expansion of birch (Betula) forest was interrupted by a dry continental phase with dominantly open grassland vegetation, coeval with the PBO (Preboreal Oscillation), as observed in the GRIP ice core. At 11 250 cal. yr BP a sudden shift to a humid climate occurred. This second change appears to be contemporaneous with: (i) a sharp 14 increase of atmospheric C; (ii) a temporary decline of atmospheric CO2; and (iii) an increase in the GRIP 10Be flux. The close correspondence with excursions of cosmogenic nuclides points to a decline in solar activity, which may have forced the changes in climate and vegetation at around 11 250 cal. yr BP. Copyright ß 2004 John Wiley & Sons, Ltd. KEYWORDS: Preboreal; solar forcing; climate change; peat; wiggle-match dating; 14C; 10Be; 18O. Introduction ventional method using a limited number of bulk peat samples. However, as a consequence of the atmospheric 14C variations in the past, no precise calendar age chronology was obtained Lake sediments and peat deposits are valuable archives for the for the Late-glacial–early Holocene part. This was mainly study of past climate change. Calendar year chronologies are of owing to the presence of two large radiocarbon plateaux within crucial importance for linking the climatic signals from differ- this time interval, at 10 000–9900 and 9600–9500 14C BP. A ent locations. Precise dating is essential for the study of leads more accurate chronology has now been obtained from AMS and lags and the potential causes and effects within the climate 14C wiggle-match dating (WMD) of selected macrofossils. This system. In this paper we compare inferred climatic change as chronology enables comparison with other chronologies of cli- recorded in a European terrestrial sequence from the Borchert mate proxies, in particular the Greenland ice-core record. (from the east of The Netherlands) with Greenland ice-core Furthermore, relationships are suggested between climate data (Fig. 1). The Borchert deposits accumulated in an aban- changes (terrestrial and Arctic), solar variability as evidenced doned channel of the former Dinkel River drainage system. by cosmogenic isotope excursions (both 14C and 10Be), and In this sequence, the early Holocene is recorded at high-reso- fluctuations in the atmospheric CO2 concentration. lution, which makes this record unique for the North Atlantic region. The detailed palynological–palaeoclimatological record from the Borchert was published by van Geel et al. (1981). Sedimentation started under lacustrine conditions dur- Methods ing the later part of the Younger Dryas and continued to ca. 3400 yr BP. Originally the sequence was 14C dated by the con- A new series of macrofossil samples (including fruits, seeds, catkin scales, bud scales, leaves and leafy stems of mosses) * Correspondence to: J. van der Plicht, Centre for Isotope Research, Radiocarbon was selected from the original Borchert sediments (Table 1). Laboratory, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The All samples were pretreated in order to remove contaminants Netherlands. E-mail: [email protected] (Mook and Streurman, 1983). Core slices were boiled in 5% 264 JOURNAL OF QUATERNARY SCIENCE Figure 1 Map of the Northern Hemisphere, with the location of the Borchert (The Netherlands) and the Summit ice-cores GRIP/GISP2 (Greenland) KOH for 10 min; the macrofossils were washed with deionised trapped cryogenically, and transferred into graphite by reduc- water over a 125–140 mm sieve, until excess humic and fulvic tion under an excess of hydrogen gas (Aerts et al., 2001). The acids were removed from the sample material. Macrofossils 14C content of the graphite was measured by the Groningen were picked out manually, selected for 14C dating, and stored AMS facility (van der Plicht et al., 2000), producing a radiocar- at a temperature of 4 C in a very dilute solution of HCl (Kilian bon age for every sample. Radiocarbon ages are reported in BP, et al., 2000). Samples were then combusted and purified to defined using the international oxalic acid standard, the con- CO2 by an automatic CN analyser. The CO2 produced was ventional half-life of 5568 yr, and correction for isotope effects Table 1 AMS radiocarbon dates from the early Holocene peat sequence from the Borchert, The Netherlands. The WMD numbers correspond to the numbers in Fig. 2C. The material dated includes selected macrofossils such as fruits, seeds, catkin scales, bud scales and leafy stems of mosses WMD number Sample number Depth (cm) Material dated Laboratory number 13C 14C age (BP) 23 62 491.2 Pinus þ Betula GrA-17590 À25.70 9550 Æ 60 22 60 492.8 Pinus þ Betula GrA-17588 À26.31 9480 Æ 60 21 58 494.4 Pinus þ Betula GrA-17578 À26.32 9520 Æ 60 20 56 496.0 Pinus þ Betula GrA-17577 À26.76 9530 Æ 70 19 54 497.6 Betula GrA-17456 À27.05 9600 Æ 60 18 52 499.2 Betula GrA-17576 À26.72 9490 Æ 60 17 50 500.8 Betula GrA-17455 À26.52 9610 Æ 50 16 48 502.4 Betula GrA-17453 À26.70 9600 Æ 50 15 45 504.8 Betula GrA-17575 À27.44 9530 Æ 60 14 42 507.2 Betula þ Populus GrA-1715 À26.14 9650 Æ 50 13 40 508.8 Betula þ Populus GrA-1717 À26.74 9700 Æ 50 12 38 510.4 Betula þ Populus GrA-1718 À25.99 9790 Æ 50 11 34A 513.6 Mosses GrA-2623 À28.28 9900 Æ 60 10 34B 513.6 Betula GrA-2654 À26.83 10,200 Æ 200 9 33 514.4 Betula þ Mosses GrA-1711 À25.69 9830 Æ 50 8 31 516.0 Betula GrA-1714 À25.78 9860 Æ 50 7 29 517.6 Betula þ Mosses GrA-1712 À25.72 9740 Æ 50 6 28A 518.4 Mosses GrA-2621 À28.09 10 050 Æ 60 5 28B 518.4 Betula GrA-2643 À27.21 10 070 Æ 100 4 26B 520.0 Betula GrA-2792 À27.23 10 400 Æ 800 3 26A 520.0 Mosses GrA-2620 À32.89 9990 Æ 60 2 24 521.6 Betula GrA-1716 À25.98 9900 Æ 50 1 22 523.2 Betula GrA-1713 À27.54 9860 Æ 50 Copyright ß 2004 John Wiley & Sons, Ltd. J. Quaternary Sci., Vol. 19(3) 263–269 (2004) PREBOREAL CLIMATE FLUCTUATIONS 265 to 13C ¼25%. Á14C denotes the atmospheric 14C content Based on changes in the AP/NAP ratio and dominant arbor- expressed as the per mil deviation of the 14C content of the oxa- eal taxa, the Preboreal biozone has been further subdivided lic acid standard, after correction for radioactive decay and into a Friesland Phase, a Rammelbeek Phase and the Late Pre- fractionation. The stable carbon isotope (13C) concentrations boreal. The Friesland Phase (Behre, 1966) is characterised by a are expressed in 13C, defined as the 13C/12C ratio of the strong rise in the values of Betula.
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