Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Diatoms as quantitative indicators of July temperature: a validation attempt at century-scale with meteorological data from northern Sweden
Responsible organisation
2003 (English)In: Palaeogeography, Palaeoclimatology, Palaeoecology, ISSN 0031-0182, E-ISSN 1872-616X, Vol. 189, no 3-4, 147-160 p.Article in journal (Refereed) Published
Abstract [en]

This study evaluates the ability of diatoms to estimate past changes in temperature by directly comparing diatom-based inferences of mean July air temperature (July T) with measured values of century-long meteorological records. The comparison includes sediment cores from three lakes in northern Sweden (Alanen Laanijarvi, 365 in above sea level (a.s.l.), Lake 850, 850 in a.s.l. and Lake Njulla, 999 in a.s.l.) dated by radioisotopic methods (Pb-210, Cs-137) and records from meteorological stations in Kiruna and Abisko. In the sediment cores of all three study lakes, benthic species dominate the diatom assemblages with percent abundance ranging from 60 to 80%. Over the past century, the diatom-based quantitative July T inferences (weighted averaging partial least squares regression and calibration) based on a regional calibration set correspond in general closely with the meteorological records. In addition, the proportion of planktonic diatoms in the stratigraphy reflects the meteorological record as well. For example, in Alanen Laanijarvi, the proportion of planktonic diatoms (e.g. Cyclotella comensis) has increased markedly since 1985, coincident with a marked increase of measured July T (> 1degreesC) at the meteorological station in nearby Kiruna. In contrast, July T in Abisko has remained relatively constant since 1985 and relatively little changes are observed in diatom assemblages in the two nearby lakes, Lake 850 and Lake Njulla. Interestingly, periods of relatively weak correspondence between measured and inferred July T (at Lake 850 from 1910 to 1940, at Lake Njulla from 1955 to 1990) correspond with periods when diatom-inferred lake-water pH shows distinct trends of lake-water pH change. Because lake-water pH is a stronger factor influencing diatom community composition than July T, the accuracy of diatom-inferred July T appears to be reduced during periods when lake-water pH fluctuates. Overall, we conclude that diatoms can provide reliable estimates of July T over the past century from sediment samples in northern Sweden and the reliability of the inferences further increases when lake-water pH remains constant. One palaeoecological implication based on these findings is that the early Holocene is likely a problematic period for estimating July T from diatoms, because natural processes such as soil development, catchment stabilisation and weathering of bedrock resulted in a marked natural decline of lake-water pH. Similarly, short-term stochastic events, such as sediment in-wash due to erosional events, forest clearance and forest fires, also may lead to inaccurate diatom-temperature inferences through changes in lake-water pH. In order to identify periods that may affect the accuracy of diatom-based July T inferences, we suggest that diatom analyses should be combined with other palaeoecological proxy indicators (e.g. pollen, chironomids). (C) 2002 Elsevier Science B.V. All rights reserved.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV , 2003. Vol. 189, no 3-4, 147-160 p.
Keyword [en]
Abisko; climatic change; diatom algae; palaeolimnology; transfer functions; radioisotopic dating; WA-PLS model validation
National Category
Natural Sciences
Identifiers
URN: urn:nbn:se:polar:diva-3578DOI: 10.1016/S0031-0182(02)00638-7OAI: oai:DiVA.org:polar-3578DiVA: diva2:1099168
Available from: 2017-05-29 Created: 2017-05-29 Last updated: 2017-05-29

Open Access in DiVA

No full text

Other links

Publisher's full text
In the same journal
Palaeogeography, Palaeoclimatology, Palaeoecology
Natural Sciences

Search outside of DiVA

GoogleGoogle Scholar

Altmetric score

Total: 4 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf