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Modest diatom responses to regional warming on the southeast Tibetan Plateau during the last two centuries

Wischnewski, J; Mackay, AW; Appleby, PG; Mischke, S; Herzschuh, U; (2011) Modest diatom responses to regional warming on the southeast Tibetan Plateau during the last two centuries. Journal of Paleolimnology , 46 (2) 215 - 227. 10.1007/s10933-011-9533-x. Green open access

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Abstract

A general mean annual temperature increase accompanied with substantial glacial retreat has been noted on the Tibetan Plateau during the last two centuries but most significantly since the mid 1950s. These climate trends are particularly apparent on the southeastern Tibetan Plateau. However, the Tibetan Plateau (due to its heterogeneous mountain landscape) has very complex and spatially differing temperature and precipitations patterns. As a result, intensive palaeolimnological investigations are necessary to decipher these climatic patterns and to understand ecological responses to recent environmental change. Here we present palaeolimnological results from a Pb-210/Cs-137-dated sediment core spanning approximately the last 200 years from a remote high-mountain lake (LC6 Lake, working name) on the southeastern Tibetan Plateau. Sediment profiles of diatoms, organic variables (TOC, C:N) and grain size were investigated. The Pb-210 record suggests a period of rapid sedimentation, which might be linked to major tectonic events in the region ca. 1950. Furthermore, unusually high Pb-210 supply rates over the last 50 years suggest that the lake has possibly been subjected to increasing precipitation rates, sediment focussing and/or increased spring thaw. The majority of diatom taxa encountered in the core are typical of slightly acidic to circumneutral, oligotrophic, electrolyte-poor lakes. Diatom species assemblages were rich, and dominated by Cyclotella sp., Achnanthes sp., Aulacoseira sp. and fragilarioid taxa. Diatom compositional change was minimal over the 200-year period (DCCA = 0.85 SD, p = 0.59); only a slightly more diverse but unstable diatom assemblage was recorded during the past 50 years. The results indicate that large-scale environmental changes recorded in the twentieth century (i.e. increased precipitation and temperatures) are likely having an affect on the LC6 Lake, but so far these impacts are more apparent on the lake geochemistry than on the diatom flora. Local and/or regional peculiarities, such as increasing precipitation and cloud cover, or localized climatic phenomena, such as negative climate feedbacks, might have offset the effects of increasing mean surface temperatures.

Type: Article
Title: Modest diatom responses to regional warming on the southeast Tibetan Plateau during the last two centuries
Open access status: An open access version is available from UCL Discovery
DOI: 10.1007/s10933-011-9533-x
Publisher version: http://dx.doi.org/10.1007/s10933-011-9533-x
Language: English
Additional information: The original publication is available at www.springerlink.com
Keywords: Diatoms, Tibetan Plateau, Mountain lake, Climate change, Lake sediments, Palaeolimnology, RECENT ENVIRONMENTAL-CHANGE, CLIMATE-CHANGE, PALEOLIMNOLOGICAL EVIDENCE, TEMPERATURE-VARIATIONS, HIMALAYAN ICE, ASIAN MONSOON, ALPINE LAKE, SHIFTS, RECORDS, CORE
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL SLASH
UCL > Provost and Vice Provost Offices > UCL SLASH > Faculty of S&HS
UCL > Provost and Vice Provost Offices > UCL SLASH > Faculty of S&HS > Dept of Geography
URI: https://discovery.ucl.ac.uk/id/eprint/1319922
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