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Holocene temperature variations at a high-altitude site in the Eastern Alps: a chironomid record from Schwarzsee ob Sölden, Austria.

Ilyashuk EA, Koinig KA, Heiri O, Ilyashuk BP, Psenner R - Quat Sci Rev (2011)

Bottom Line: The chironomid record suggests a climate transition between ca 5200 and 4500 cal yr BP to cooler T(July).A distinct cooling trend is evident from ca 4500 until ca 2500 cal yr BP.Thereafter, the study site experienced its coldest conditions (around 4 °C or less) throughout the rest of the Holocene, with the exception of the warming trend during the late 20th century.

View Article: PubMed Central - PubMed

Affiliation: Institute of Ecology, University of Innsbruck, Technikerstraße 25, A-6020 Innsbruck, Austria.

ABSTRACT
Few well-dated, quantitative Holocene temperature reconstructions exist from high-altitude sites in the Central Eastern Alps. Here, we present a chironomid-based quantitative reconstruction of mean July air temperatures (T(July)) throughout the Holocene for a remote high-mountain lake, Schwarzsee ob Sölden, situated above the treeline at 2796 m a.s.l. in the Austrian Alps. Applying a chironomid-temperature inference model developed from lakes of the Alpine region to a high-resolution chironomid record from the lake provides evidence for early Holocene (ca 10000-8600 cal yr BP) T(July) of up to 8.5 °C, i.e. >4 °C above the modern (1977-2006) mean July temperature. The reconstruction reveals the so-called '8.2-ka cold event' centered at ca 8250-8000 cal yr BP with temperatures ca 3 °C below the early-Holocene thermal maximum. Rather warm (ca 6 °C) and productive conditions prevailed during ca 7900-4500 cal yr BP. The chironomid record suggests a climate transition between ca 5200 and 4500 cal yr BP to cooler T(July). A distinct cooling trend is evident from ca 4500 until ca 2500 cal yr BP. Thereafter, the study site experienced its coldest conditions (around 4 °C or less) throughout the rest of the Holocene, with the exception of the warming trend during the late 20th century. Beside other factors, the Northern Hemisphere summer insolation seems to be the major driving force for the long-term trends in T(July) at high altitudes in the Eastern Alps. Due to the extreme location of the lake and the limited temperature range represented by the applied calibration data set, the chironomid-based temperature reconstruction fails to track phases of the late-Holocene climatic history with T(July) cooler than 4 °C. Further chironomid-based palaeoclimate model and down-core studies are required to address this problem, provide more realistic T(July) estimates from undisturbed high-altitude lakes in the Alps, and extract a reliable regional temperature signal.

No MeSH data available.


Related in: MedlinePlus

(A) Map showing the location of Schwarzsee ob Sölden (SOS) in the Alpine region. (B) Photograph of SOS and its catchment, looking towards the north. (C) Bathymetric map of SOS showing the coring site (closed circle) and the modern zoobenthos sampling transect (dashed line).
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fig1: (A) Map showing the location of Schwarzsee ob Sölden (SOS) in the Alpine region. (B) Photograph of SOS and its catchment, looking towards the north. (C) Bathymetric map of SOS showing the coring site (closed circle) and the modern zoobenthos sampling transect (dashed line).

Mentions: Schwarzsee ob Sölden (SOS; 46°57′57″N; 10°56′46″E) is a remote high-alpine (2796 m a.s.l.) lake situated above treeline in the Ötztaler Alps (the Central Eastern Alps), Tyrol, Austria (Fig. 1). The maximum depth is 17.5 m and the surface area is 3.5 ha. About 1.5 ha of the lake bottom is covered with soft sediment. The lake has been monitored annually since 1985 by the Institute of Ecology, the University of Innsbruck. The lake is oligotrophic with a concentration of total phosphorus <5 μg l−1. From 1985 to 2008, conductivity has increased from 10 to 31 μS cm−1. At the same time the mean lake-water pH has increased from 5.6 to 6.1.


Holocene temperature variations at a high-altitude site in the Eastern Alps: a chironomid record from Schwarzsee ob Sölden, Austria.

Ilyashuk EA, Koinig KA, Heiri O, Ilyashuk BP, Psenner R - Quat Sci Rev (2011)

(A) Map showing the location of Schwarzsee ob Sölden (SOS) in the Alpine region. (B) Photograph of SOS and its catchment, looking towards the north. (C) Bathymetric map of SOS showing the coring site (closed circle) and the modern zoobenthos sampling transect (dashed line).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3021123&req=5

fig1: (A) Map showing the location of Schwarzsee ob Sölden (SOS) in the Alpine region. (B) Photograph of SOS and its catchment, looking towards the north. (C) Bathymetric map of SOS showing the coring site (closed circle) and the modern zoobenthos sampling transect (dashed line).
Mentions: Schwarzsee ob Sölden (SOS; 46°57′57″N; 10°56′46″E) is a remote high-alpine (2796 m a.s.l.) lake situated above treeline in the Ötztaler Alps (the Central Eastern Alps), Tyrol, Austria (Fig. 1). The maximum depth is 17.5 m and the surface area is 3.5 ha. About 1.5 ha of the lake bottom is covered with soft sediment. The lake has been monitored annually since 1985 by the Institute of Ecology, the University of Innsbruck. The lake is oligotrophic with a concentration of total phosphorus <5 μg l−1. From 1985 to 2008, conductivity has increased from 10 to 31 μS cm−1. At the same time the mean lake-water pH has increased from 5.6 to 6.1.

Bottom Line: The chironomid record suggests a climate transition between ca 5200 and 4500 cal yr BP to cooler T(July).A distinct cooling trend is evident from ca 4500 until ca 2500 cal yr BP.Thereafter, the study site experienced its coldest conditions (around 4 °C or less) throughout the rest of the Holocene, with the exception of the warming trend during the late 20th century.

View Article: PubMed Central - PubMed

Affiliation: Institute of Ecology, University of Innsbruck, Technikerstraße 25, A-6020 Innsbruck, Austria.

ABSTRACT
Few well-dated, quantitative Holocene temperature reconstructions exist from high-altitude sites in the Central Eastern Alps. Here, we present a chironomid-based quantitative reconstruction of mean July air temperatures (T(July)) throughout the Holocene for a remote high-mountain lake, Schwarzsee ob Sölden, situated above the treeline at 2796 m a.s.l. in the Austrian Alps. Applying a chironomid-temperature inference model developed from lakes of the Alpine region to a high-resolution chironomid record from the lake provides evidence for early Holocene (ca 10000-8600 cal yr BP) T(July) of up to 8.5 °C, i.e. >4 °C above the modern (1977-2006) mean July temperature. The reconstruction reveals the so-called '8.2-ka cold event' centered at ca 8250-8000 cal yr BP with temperatures ca 3 °C below the early-Holocene thermal maximum. Rather warm (ca 6 °C) and productive conditions prevailed during ca 7900-4500 cal yr BP. The chironomid record suggests a climate transition between ca 5200 and 4500 cal yr BP to cooler T(July). A distinct cooling trend is evident from ca 4500 until ca 2500 cal yr BP. Thereafter, the study site experienced its coldest conditions (around 4 °C or less) throughout the rest of the Holocene, with the exception of the warming trend during the late 20th century. Beside other factors, the Northern Hemisphere summer insolation seems to be the major driving force for the long-term trends in T(July) at high altitudes in the Eastern Alps. Due to the extreme location of the lake and the limited temperature range represented by the applied calibration data set, the chironomid-based temperature reconstruction fails to track phases of the late-Holocene climatic history with T(July) cooler than 4 °C. Further chironomid-based palaeoclimate model and down-core studies are required to address this problem, provide more realistic T(July) estimates from undisturbed high-altitude lakes in the Alps, and extract a reliable regional temperature signal.

No MeSH data available.


Related in: MedlinePlus