Holocene vegetation and climate history on a continental-oceanic transect in northern Fennoscandia based on pollen and plant macrofossils

Bjune, Anne E.; Birks, H. John B.; Seppä, Heikki

doi:10.1080/03009480410001244

Cited by 109 publications

(47 citation statements)

References 39 publications

(33 reference statements)

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“…However, modern-like fjords and glaciers which trigger such plumes almost certainly did not exist during the Pliocene. The increase in Sphagnum spores and the slight decline in Pinus pollen in the mid-to late Holocene sample have been interpreted to reflect the expansion of peatlands that is observed in the late Holocene vegetation records from northern Norway (Bjune et al, 2004). Deciduous trees such as Alnus and Betula are common elements in terrestrial Holocene vegetation records (see, e.g., Bjune and Birks, 2008;Bjune, 2005) but are only represented in low numbers (< 3 %) in the marine surface pollen assemblages, complicating the quantification of their representation in the vegetation.…”

Section: Modern Pollen Assemblages and Vegetationmentioning

confidence: 99%

Climate variability and long-term expansion of peatlands in Arctic Norway during the late Pliocene (ODP Site 642, Norwegian Sea)

et al. 2016

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Abstract.Little is known about the terrestrial response of high-latitude Scandinavian vegetation to the warmerthan-present climate of the late Pliocene (Piacenzian, 3.60-2.58 Ma). In order to assess Piacenzian terrestrial climate variability, we present the first high-resolution reconstruction of vegetation and climate change in northern Norway between 3.6 and 3.14 Ma. The reconstructions are derived from pollen assemblages in the marine sediments of ODP Hole 642B, Norwegian Sea (67 • N). The palynological assemblages provide a unique record of latitudinal and altitudinal shifting of the forest boundaries, with vegetation alternating between cool temperate forest during warmerthan-present intervals and boreal forest similar to today during cooler intervals. The northern boundary of the nemoral to boreonemoral forest zone was displaced at least 4-8 • further north, and warmest-month temperatures were 6-14.5 • C higher than at present during warm phases. Warm climatic conditions persisted during the earliest Piacenzian (ca. 3.6-3.47 Ma) with diverse cool temperate nemoral to boreonemoral forests growing in the lowlands of the Scandinavian mountains. A distinct cooling event at ca. 3.47 Ma resulted in a southward shift of vegetation zones, leading to the predominance of boreal forest and the development of open, low alpine environments. The cooling culminated around 3.3 Ma, coinciding with Marine Isotope Stage (MIS) M2. Warmer climate conditions returned after ca. 3.29 Ma, with higher climate variability indicated by the repeated expansion of forests and peatlands during warmer and cooler periods, respectively. Climate progressively cooled after 3.18 Ma, resembling climatic conditions during MIS M2. A high variability of Norwegian vegetation and climate changes during the Piacenzian is superimposed on a long-term cooling trend. This cooling was accompanied by an expansion of Sphagnum peatlands that potentially contributed to the decline in atmospheric CO 2 concentrations at the end of the Piacenzian warm period and facilitated ice growth through positive vegetation-snow albedo feedbacks. Correlations with other Northern Hemisphere vegetation records suggest hemisphere-wide effects of climate cooling.

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Section: Modern Pollen Assemblages and Vegetationmentioning

confidence: 99%

Climate variability and long-term expansion of peatlands in Arctic Norway during the late Pliocene (ODP Site 642, Norwegian Sea)

et al. 2016

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“…Several temperature reconstructions covering different areas of the globe are now available, ranging from multidecadal to seasonal time scale. They were obtained from different proxy data such as tree rings (Briffa et al, 2004;Cook et al, 2002;Esper et al, 2002;D'Arrigo et al, 2006;Osborn et al, 2006), fossil pollen (Bjune et al, 2004;Larocque and Hall, 2004), ice cores (Jouzel et al, 2001; Published by Copernicus Publications on behalf of the European Geosciences Union.…”

Section: Introductionmentioning

confidence: 99%

Influence of solar variability, CO<sub>2</sub> and orbital forcing between 1000 and 1850 AD in the IPSLCM4 model

et al. 2010

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Abstract. Studying the climate of the last millennium gives the possibility to deal with a relatively well-documented climate essentially driven by natural forcings. We have performed two simulations with the IPSLCM4 climate model to evaluate the impact of Total Solar Irradiance (TSI), CO 2 and orbital forcing on secular temperature variability during the preindustrial part of the last millennium. The Northern Hemisphere (NH) temperature of the simulation reproduces the amplitude of the NH temperature reconstructions over the last millennium. Using a linear statistical decomposition we evaluated that TSI and CO 2 have similar contributions to secular temperature variability between 1425 and 1850 AD. They generate a temperature minimum comparable to the Little Ice Age shown by the temperature reconstructions. Solar forcing explains ∼80% of the NH temperature variability during the first part of the millennium (1000-1425 AD) including the Medieval Climate Anomaly (MCA). It is responsible for a warm period which occurs two centuries later than in the reconstructions. This mismatch implies that the secular variability during the MCA is not fully explained by the response of the model to the TSI reconstruction.With a signal-noise ratio (SNR) estimate we found that the temperature signal of the forced simulation is significantly different from internal variability over area wider than ∼5.10 6 km 2 , i.e. approximately the extent of Europe. Orbital forcing plays a significant role in latitudes higher than 65 • N in summer and supports the conclusions of a recent study Correspondence to: J. Servonnat (jerome.servonnat@lsce.ipsl.fr) on an Arctic temperature reconstruction over past two millennia. The forced variability represents at least half of the temperature signal on only ∼30% of the surface of the globe. This study suggests that regional reconstructions of the temperature between 1000 and 1850 AD are likely to show weak signatures of solar, CO 2 and orbital forcings compared to internal variability.

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“…Lake Storsjön itself covers an area of 456 km 2 , with 13% of the catchment area consisting of lakes. The lake has a mean depth of 17.3 m, a maximum depth of 74 m and a volume of 8.02 km 3 . It can be divided into five principal parts (A to E; Figure 1d) according to its bathymetry and exposure to inlets and to the outlet.…”

Section: Study Areamentioning

confidence: 99%

“…Hydrodynamic simulations revealed significant surface currents associated with prevailing wind patterns during the ice-free season and distinct deeper currents linked to the lake floor morphology [45]. The lake has a mean depth of 17.3 m, a maximum depth of 74 m and a volume of 8.02 km 3 . It can be divided into five principal parts (A to E; Figure 1d) according to its bathymetry and exposure to inlets and to the outlet.…”

Section: Study Areamentioning

confidence: 99%

“…Numerous Holocene palaeoclimate studies have been performed in Scandinavia, many of which are based on lake sediment records [1][2][3][4][5][6][7]. The Scandes Mountains are particularly important for our understanding of climate variations in this region through their wealth of suitable sites along ecological gradients and their proximity to the climatically dynamic North Atlantic region [8][9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

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Holocene Hydroclimate Variability in Central Scandinavia Inferred from Flood Layers in Contourite Drift Deposits in Lake Storsjön

et al. 2018

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Despite the societal importance of extreme hydroclimate events, few palaeoenvironmental studies of Scandinavian lake sediments have investigated flood occurrences. Here we present a flood history based on lithological, geochemical and mineral magnetic records of a Holocene sediment sequence collected from contourite drift deposits in Lake Storsjön (63.12 • N, 14.37 • E). After the last deglaciation, the lake began to form around 9800 cal yr BP, but glacial activity persisted in the catchment for~250 years. Element concentrations and mineral magnetic properties of the sediments indicate relatively stable sedimentation conditions during the Holocene. However, human impact in the form of expanding agriculture is evident from about 1100 cal yr BP, and intensified in the 20th century. Black layers containing iron sulphide appear irregularly throughout the sequence. The increased influx of organic matter during flood events led to decomposition and oxygen consumption, and eventually to anoxic conditions in the interstitial water preserving these layers. Elevated frequencies of black layer occurrence between 3600 and 1800 cal yr BP reflect vegetation changes in the catchment as well as large-scale climatic change. Soil erosion during snowmelt flood events increased with a tree line descent since the onset of the neoglacial period (~4000 cal yr BP). The peak in black layer occurrence coincides with a prominent solar minimum~2600 cal yr BP, which may have accentuated the observed pattern due to the prevalence of a negative NAO index, a longer snow accumulation period and consequently stronger snowmelt floods.

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Holocene vegetation and climate history on a continental-oceanic transect in northern Fennoscandia based on pollen and plant macrofossils

Cited by 109 publications

References 39 publications

Climate variability and long-term expansion of peatlands in Arctic Norway during the late Pliocene (ODP Site 642, Norwegian Sea)

Climate variability and long-term expansion of peatlands in Arctic Norway during the late Pliocene (ODP Site 642, Norwegian Sea)

Influence of solar variability, CO<sub>2</sub> and orbital forcing between 1000 and 1850 AD in the IPSLCM4 model

Holocene Hydroclimate Variability in Central Scandinavia Inferred from Flood Layers in Contourite Drift Deposits in Lake Storsjön

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Holocene vegetation and climate history on a continental-oceanic transect in northern Fennoscandia based on pollen and plant macrofossils

Cited by 109 publications

References 39 publications

Climate variability and long-term expansion of peatlands in Arctic Norway during the late Pliocene (ODP Site 642, Norwegian Sea)

Climate variability and long-term expansion of peatlands in Arctic Norway during the late Pliocene (ODP Site 642, Norwegian Sea)

Influence of solar variability, CO&lt;sub&gt;2&lt;/sub&gt; and orbital forcing between 1000 and 1850 AD in the IPSLCM4 model

Holocene Hydroclimate Variability in Central Scandinavia Inferred from Flood Layers in Contourite Drift Deposits in Lake Storsjön

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Influence of solar variability, CO<sub>2</sub> and orbital forcing between 1000 and 1850 AD in the IPSLCM4 model