Late Holocene climate development of Bjørnøya, Svalbard, based on chironomid analysis
Recent climate related changes in the Arctic have risen concern and interest to better understand the mechamisms of arctic climate system and to predict the future response. Due to short instrumental monitoring a palaeoenvironmental view is required to reveal and understand long-term changes, yet hi...
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ftunivhelsihelda:oai:helda.helsinki.fi:10138/144210 2023-08-20T04:04:14+02:00 Late Holocene climate development of Bjørnøya, Svalbard, based on chironomid analysis Kivilä, Henriikka Helsingin yliopisto, Matemaattis-luonnontieteellinen tiedekunta, Geotieteiden ja maantieteen laitos University of Helsinki, Faculty of Science, Department of Geosciences and Geography Helsingfors universitet, Matematisk-naturvetenskapliga fakulteten, Institutionen för geovetenskaper och geografi 2014 application/pdf http://hdl.handle.net/10138/144210 eng eng Helsingfors universitet University of Helsinki Helsingin yliopisto URN:NBN:fi-fe2017112251745 http://hdl.handle.net/10138/144210 Geology Geologia Geologi pro gradu-avhandlingar pro gradu -tutkielmat master's thesis 2014 ftunivhelsihelda 2023-07-28T06:13:00Z Recent climate related changes in the Arctic have risen concern and interest to better understand the mechamisms of arctic climate system and to predict the future response. Due to short instrumental monitoring a palaeoenvironmental view is required to reveal and understand long-term changes, yet high-resolution palaeoecological and -climatological studies are sparse. Bjørnøya, the Bear Island, (74°30' N, 19° E) is a key site for terrestrial palaeoclimate records along the heat transport system of the North Atlantic Current, with the possibility of linking records from northern Fennoscandia and Arctic Svalbard. A summer temperature series for the past ca. 1000 years was reconstructed from a 64 cm surface sediment core from lake Ellasjøen, SW Bjørnøya, based on quantitative palaeoenvironmental modelling of subfossilized chironomid assemblages. Quality of reconstructions was assessed with modern analogue technique and principal component analysis. To support the interpretation and receive a more holistic view of the lake history, in- lake processes, catchment interaction and factors behind the changes, a multi-proxy approach was chosen. Sediment physical characteristics: water content, loss-on-ignition, magnetic susceptibility and spectrocolorimetric identification of sedimentary signatures and components, in addition to composition and diversity of the chironomid assemblage, were used to trace a comprehensive picture of past changes. Radiometric dating was conducted to assess the temporal context of the sedimentary series. The results reveal that Ellasjøen is a climatically sensitive lake and preserves a history of substantial changes. A general pattern is detected where Medieval Warm Period features very modest warmth, followed by warming summer temperatures until 1600 AD, when the temperature trend starts to decrease towards culmination of the Little Ice Age at 1740 AD. A warming trend ever since is persistent but does not exceed past warmth. Results suggest higher seasonality during Little Ice Age and seek to ... Master Thesis Arctic Bear Island Bjørnøya Bjørnøya Fennoscandia Magnetic susceptibility north atlantic current North Atlantic Svalbard Helsingfors Universitet: HELDA – Helsingin yliopiston digitaalinen arkisto Arctic Bear Island ENVELOPE(-67.250,-67.250,-68.151,-68.151) Bjørnøya ENVELOPE(-67.250,-67.250,-68.151,-68.151) Ellasjøen ENVELOPE(19.031,19.031,74.388,74.388) Svalbard |
institution |
Open Polar |
collection |
Helsingfors Universitet: HELDA – Helsingin yliopiston digitaalinen arkisto |
op_collection_id |
ftunivhelsihelda |
language |
English |
topic |
Geology Geologia Geologi |
spellingShingle |
Geology Geologia Geologi Kivilä, Henriikka Late Holocene climate development of Bjørnøya, Svalbard, based on chironomid analysis |
topic_facet |
Geology Geologia Geologi |
description |
Recent climate related changes in the Arctic have risen concern and interest to better understand the mechamisms of arctic climate system and to predict the future response. Due to short instrumental monitoring a palaeoenvironmental view is required to reveal and understand long-term changes, yet high-resolution palaeoecological and -climatological studies are sparse. Bjørnøya, the Bear Island, (74°30' N, 19° E) is a key site for terrestrial palaeoclimate records along the heat transport system of the North Atlantic Current, with the possibility of linking records from northern Fennoscandia and Arctic Svalbard. A summer temperature series for the past ca. 1000 years was reconstructed from a 64 cm surface sediment core from lake Ellasjøen, SW Bjørnøya, based on quantitative palaeoenvironmental modelling of subfossilized chironomid assemblages. Quality of reconstructions was assessed with modern analogue technique and principal component analysis. To support the interpretation and receive a more holistic view of the lake history, in- lake processes, catchment interaction and factors behind the changes, a multi-proxy approach was chosen. Sediment physical characteristics: water content, loss-on-ignition, magnetic susceptibility and spectrocolorimetric identification of sedimentary signatures and components, in addition to composition and diversity of the chironomid assemblage, were used to trace a comprehensive picture of past changes. Radiometric dating was conducted to assess the temporal context of the sedimentary series. The results reveal that Ellasjøen is a climatically sensitive lake and preserves a history of substantial changes. A general pattern is detected where Medieval Warm Period features very modest warmth, followed by warming summer temperatures until 1600 AD, when the temperature trend starts to decrease towards culmination of the Little Ice Age at 1740 AD. A warming trend ever since is persistent but does not exceed past warmth. Results suggest higher seasonality during Little Ice Age and seek to ... |
author2 |
Helsingin yliopisto, Matemaattis-luonnontieteellinen tiedekunta, Geotieteiden ja maantieteen laitos University of Helsinki, Faculty of Science, Department of Geosciences and Geography Helsingfors universitet, Matematisk-naturvetenskapliga fakulteten, Institutionen för geovetenskaper och geografi |
format |
Master Thesis |
author |
Kivilä, Henriikka |
author_facet |
Kivilä, Henriikka |
author_sort |
Kivilä, Henriikka |
title |
Late Holocene climate development of Bjørnøya, Svalbard, based on chironomid analysis |
title_short |
Late Holocene climate development of Bjørnøya, Svalbard, based on chironomid analysis |
title_full |
Late Holocene climate development of Bjørnøya, Svalbard, based on chironomid analysis |
title_fullStr |
Late Holocene climate development of Bjørnøya, Svalbard, based on chironomid analysis |
title_full_unstemmed |
Late Holocene climate development of Bjørnøya, Svalbard, based on chironomid analysis |
title_sort |
late holocene climate development of bjørnøya, svalbard, based on chironomid analysis |
publisher |
Helsingfors universitet |
publishDate |
2014 |
url |
http://hdl.handle.net/10138/144210 |
long_lat |
ENVELOPE(-67.250,-67.250,-68.151,-68.151) ENVELOPE(-67.250,-67.250,-68.151,-68.151) ENVELOPE(19.031,19.031,74.388,74.388) |
geographic |
Arctic Bear Island Bjørnøya Ellasjøen Svalbard |
geographic_facet |
Arctic Bear Island Bjørnøya Ellasjøen Svalbard |
genre |
Arctic Bear Island Bjørnøya Bjørnøya Fennoscandia Magnetic susceptibility north atlantic current North Atlantic Svalbard |
genre_facet |
Arctic Bear Island Bjørnøya Bjørnøya Fennoscandia Magnetic susceptibility north atlantic current North Atlantic Svalbard |
op_relation |
URN:NBN:fi-fe2017112251745 http://hdl.handle.net/10138/144210 |
_version_ |
1774714636314083328 |