Abrupt Holocene climate transitions in the northern North Atlantic region recorded by synchronized lacustrine records in Iceland Geirsdóttir, A.; Miller, G.H.; Larsen, D.J.; Olafsdottir, S. Geirsdóttir, A. Miller, G.H. Larsen, D.J. Olafsdottir, S. Arctic Little Ice Age (LIA) Medieval Warm Period abrupt climate change earth science/paleoclimate/paleolimnology (carbon/nitrogen,sediment,null,dimensionless,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (volume magnetic susceptibility,sediment,null,dimensionless (SI system),null,paleolimnology,null,gamma ray attenuation porosity evaluation,N,null) earth science/paleoclimate/paleolimnology (carbon/nitrogen,sediment,null,dimensionless,null,paleolimnology,resampled,null,N,null) earth science/paleoclimate/paleolimnology (carbon/nitrogen,sediment,null,standard deviation unit,null,paleolimnology,normalized|resampled,null,N,null) earth science/paleoclimate/paleolimnology (organic carbon,sediment,null,standard deviation unit,null,paleolimnology,normalized|resampled,null,N,null) earth science/paleoclimate/paleolimnology (carbon,sediment,null,percent,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (biogenic silica,sediment,null,standard deviation unit,null,paleolimnology,normalized|resampled,null,N,null) earth science/paleoclimate/paleolimnology (volume magnetic susceptibility,sediment,null,standard deviation unit,null,paleolimnology,normalized|resampled,gamma ray attenuation porosity evaluation,N,null) earth science/paleoclimate/paleolimnology (sedimentation rate,sediment,null,centimeter per year,null,paleolimnology,resampled,null,N,null) earth science/paleoclimate/paleolimnology (sedimentation rate,sediment,null,standard deviation unit,null,paleolimnology,normalized|resampled,null,N,null) earth science/paleoclimate/paleolimnology (age,null,null,calendar year before present,null,paleolimnology,null,null,N,present is 2000 AD) earth science/paleoclimate/paleolimnology (organic carbon,sediment,null,milligram per gram,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (organic carbon,sediment,null,percent,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (density,sediment,null,gram per cubic centimeter,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (sedimentation rate,sediment,null,centimeter per year,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (biogenic silica,sediment,null,percent,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (carbon,sediment,null,percent,null,paleolimnology,resampled,null,N,null) earth science/paleoclimate/paleolimnology (organic carbon,sediment,null,percent,null,paleolimnology,resampled,null,N,null) earth science/paleoclimate/paleolimnology (volume magnetic susceptibility,sediment,null,dimensionless (SI system),null,paleolimnology,resampled,gamma ray attenuation porosity evaluation,N,null) earth science/paleoclimate/paleolimnology (biogenic silica,sediment,null,percent,null,paleolimnology,resampled,null,N,null) earth science/paleoclimate/paleolimnology (density,sediment,null,gram per cubic centimeter,null,paleolimnology,resampled,null,N,null) earth science/paleoclimate/paleolimnology (biogenic silica,sediment,null,milligram per gram,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (delta 13C,organic matter,null,per mil VPDB,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (delta 13C,organic matter,null,standard deviation unit,null,paleolimnology,normalized|resampled,null,N,null) earth science/paleoclimate/paleolimnology (biogenic silica,sediment,null,milligram per gram,null,paleolimnology,resampled,null,N,null) earth science/paleoclimate/paleolimnology (delta 13C,organic matter,null,per mil VPDB,null,paleolimnology,resampled,null,N,null) earth science/paleoclimate/paleolimnology (age,null,null,calendar year before present,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (density,sediment,null,standard deviation unit,null,paleolimnology,normalized|resampled,null,N,null) earth science/paleoclimate/paleolimnology (carbon,sediment,null,standard deviation unit,null,paleolimnology,normalized|resampled,null,N,null) earth science/paleoclimate/paleolimnology earth science/paleoclimate/paleolimnology earth science/paleoclimate/paleolimnology earth science/paleoclimate/paleolimnology (Lake Hvítárvatn>LATITUDE 64.613723>LONGITUDE -19.843769) (Lake Haukadalsvatn>LATITUDE 65.055846>LONGITUDE -21.625757) Two high-sediment-accumulation-rate Icelandic lakes, the glacial lake Hvítárvatn and the non-glacial lake Haukadalsvatn, contain numerous tephra layers of known age, which together with highresolution paleomagnetic secular variations allow synchronization with a well-dated marine core from the shelf north of Iceland. A composite standardized climate record from the two lakes provides a single time series that efficiently integrates multi-proxy data that reflect the evolution of summer temperatures through the Holocene. The first-order trends in biogenic silica (BSi), d13C, and C:N rise relatively abruptly following deglaciation, reaching maximum values shortly after 8 ka following a complex minimum between 8.7 and 8.0 ka. The Holocene Thermal Maximum (HTM) in the lakes is marked by all proxies, with a sharp transition out of the 8 ka cold event into peak summer warmth by 7.9 ka, and continuing warm with some fluctuations until 5.5 ka. Decreasing summer insolation after the HTM is reflected by incremental cooling, initially w5.5 ka, with subsequent cold perturbations recorded by all proxies 4.3 to 4.0 ka and 3.1 to 2.8 ka. The strongest disturbance occurred after 2 ka with initial summer cooling occurring between 1.4 and 1.0 ka, followed by a more severe drop in summer temperatures after 0.7 ka culminating between 0.5 and 0.2 ka. Following each late Holocene cold departure, BSi re-equilibrated at a lower value independent of the sediment accumulation rate. Some of the abrupt shifts may be related to Icelandic volcanism influencing catchment stability, but the lack of a full recovery to pre-existing values after the perturbation suggests increased periglacial activity, decreased vegetation cover, and glacier growth in the highlands of Iceland. The similarity in timing, direction and magnitude of our multi-proxy records from glacial and non-glacial lakes, and from the adjacent marine shelf, suggests that our composite record reflects large-scale shifts in ocean/atmosphere circulation throughout the northern North Atlantic. STUDY NOTES: Keywords - Iceland, Lake sediment, Holocene paleoclimate, Abrupt climate transitions, 8.2 Event, Holocene Thermal Maximum, Neoglaciation, Medieval warm period, Little Ice Age. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Geirsdóttir, A. Investigator : Miller, G.H. Investigator : Larsen, D.J. Investigator : Olafsdottir, S. 2014-02-25 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/16279 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/iceland/hak-geirsdottir-2013-raw-d13c-cn-bsi.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/iceland/hvt-geirsdottir-2013-raw-cn.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/iceland/hvt-geirsdottir-2013-resampled-sar.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/iceland/hvt-geirsdottir-2013-resampled-bsi.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/iceland/hvt-geirsdottir-2013-raw-tc.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/iceland/hvt-geirsdottir-2013-raw-density.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/iceland/hvt-geirsdottir-2013-resampled-tc.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/iceland/hak-geirsdottir-2013-resampled-d13c-cn-bsi.txt 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https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/iceland/hvt-geirsdottir-2013-raw-cn.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/iceland/hvt-geirsdottir-2013-resampled-sar.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/iceland/hvt-geirsdottir-2013-resampled-bsi.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/iceland/hvt-geirsdottir-2013-raw-tc.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/iceland/hvt-geirsdottir-2013-raw-density.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/iceland/hvt-geirsdottir-2013-resampled-tc.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/iceland/hak-geirsdottir-2013-resampled-d13c-cn-bsi.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/iceland/hvt-geirsdottir-2013-raw-bsi.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/iceland/hak-geirsdottir-2013-resampled-sar-toc-ms.txt 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Miller, D.J. Larsen, S. Ólafsdóttir2013Abrupt Holocene climate transitions in the northern North Atlantic region recorded by synchronized lacustrine records in IcelandQuaternary Science Reviews7048-62dx.doi.org/10.1016/j.quascirev.2013.03.010 START YEAR: 10300 cal yr BP * END YEAR: -56 cal yr BP -21.625757 64.613723 -19.843769 65.055846