Evidence for cooler European summers during periods of changing meltwater flux to the North Atlantic
We analyzed fossil chironomids (nonbiting midges) and pollen in two lake-sediment records to reconstruct and quantify Holocene summer-temperature fluctuations in the European Alps. Chironomid and pollen records indicate five centennial-scale cooling episodes during the early- and mid-Holocene. The s...
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ftpubmed:oai:pubmedcentral.nih.gov:524458 2023-05-15T17:29:14+02:00 Evidence for cooler European summers during periods of changing meltwater flux to the North Atlantic Heiri, Oliver Tinner, Willy Lotter, André F. 2004-10-26 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC524458 http://www.ncbi.nlm.nih.gov/pubmed/15492214 https://doi.org/10.1073/pnas.0406594101 en eng National Academy of Sciences http://www.ncbi.nlm.nih.gov/pmc/articles/PMC524458 http://www.ncbi.nlm.nih.gov/pubmed/15492214 http://dx.doi.org/10.1073/pnas.0406594101 Copyright © 2004, The National Academy of Sciences Physical Sciences Text 2004 ftpubmed https://doi.org/10.1073/pnas.0406594101 2013-08-30T03:18:10Z We analyzed fossil chironomids (nonbiting midges) and pollen in two lake-sediment records to reconstruct and quantify Holocene summer-temperature fluctuations in the European Alps. Chironomid and pollen records indicate five centennial-scale cooling episodes during the early- and mid-Holocene. The strongest temperature declines of ≈1°C are inferred at ≈10,700–10,500 and 8,200–7,600 calibrated 14C years B.P., whereas other temperature fluctuations are of smaller amplitude. Two forcing mechanisms have been presented recently to explain centennial-scale climate variability in Europe during the early- and mid-Holocene, both involving changes in Atlantic thermohaline circulation. In the first mechanism, changes in meltwater flux from the North American continent to the North Atlantic are responsible for changes in the Atlantic thermohaline circulation, thereby affecting circum-Atlantic climate. In the second mechanism, solar variability is the cause of Holocene climatic fluctuations, possibly triggering changes in Atlantic thermohaline overturning. Within their dating uncertainty, the two major cooling periods in the European Alps are coeval with substantial changes in the routing of North American freshwater runoff to the North Atlantic, whereas quantitatively, our climatic reconstructions show a poor agreement with available records of past solar activity. Thus, our results suggest that, during the early- and mid-Holocene, freshwater-induced Atlantic circulation changes had stronger influence on Alpine summer temperatures than solar variability and that Holocene thermohaline circulation reductions have led to summer-temperature declines of up to 1°C in central Europe. Text North Atlantic PubMed Central (PMC) Proceedings of the National Academy of Sciences 101 43 15285 15288 |
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English |
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Physical Sciences |
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Physical Sciences Heiri, Oliver Tinner, Willy Lotter, André F. Evidence for cooler European summers during periods of changing meltwater flux to the North Atlantic |
topic_facet |
Physical Sciences |
description |
We analyzed fossil chironomids (nonbiting midges) and pollen in two lake-sediment records to reconstruct and quantify Holocene summer-temperature fluctuations in the European Alps. Chironomid and pollen records indicate five centennial-scale cooling episodes during the early- and mid-Holocene. The strongest temperature declines of ≈1°C are inferred at ≈10,700–10,500 and 8,200–7,600 calibrated 14C years B.P., whereas other temperature fluctuations are of smaller amplitude. Two forcing mechanisms have been presented recently to explain centennial-scale climate variability in Europe during the early- and mid-Holocene, both involving changes in Atlantic thermohaline circulation. In the first mechanism, changes in meltwater flux from the North American continent to the North Atlantic are responsible for changes in the Atlantic thermohaline circulation, thereby affecting circum-Atlantic climate. In the second mechanism, solar variability is the cause of Holocene climatic fluctuations, possibly triggering changes in Atlantic thermohaline overturning. Within their dating uncertainty, the two major cooling periods in the European Alps are coeval with substantial changes in the routing of North American freshwater runoff to the North Atlantic, whereas quantitatively, our climatic reconstructions show a poor agreement with available records of past solar activity. Thus, our results suggest that, during the early- and mid-Holocene, freshwater-induced Atlantic circulation changes had stronger influence on Alpine summer temperatures than solar variability and that Holocene thermohaline circulation reductions have led to summer-temperature declines of up to 1°C in central Europe. |
format |
Text |
author |
Heiri, Oliver Tinner, Willy Lotter, André F. |
author_facet |
Heiri, Oliver Tinner, Willy Lotter, André F. |
author_sort |
Heiri, Oliver |
title |
Evidence for cooler European summers during periods of changing meltwater flux to the North Atlantic |
title_short |
Evidence for cooler European summers during periods of changing meltwater flux to the North Atlantic |
title_full |
Evidence for cooler European summers during periods of changing meltwater flux to the North Atlantic |
title_fullStr |
Evidence for cooler European summers during periods of changing meltwater flux to the North Atlantic |
title_full_unstemmed |
Evidence for cooler European summers during periods of changing meltwater flux to the North Atlantic |
title_sort |
evidence for cooler european summers during periods of changing meltwater flux to the north atlantic |
publisher |
National Academy of Sciences |
publishDate |
2004 |
url |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC524458 http://www.ncbi.nlm.nih.gov/pubmed/15492214 https://doi.org/10.1073/pnas.0406594101 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC524458 http://www.ncbi.nlm.nih.gov/pubmed/15492214 http://dx.doi.org/10.1073/pnas.0406594101 |
op_rights |
Copyright © 2004, The National Academy of Sciences |
op_doi |
https://doi.org/10.1073/pnas.0406594101 |
container_title |
Proceedings of the National Academy of Sciences |
container_volume |
101 |
container_issue |
43 |
container_start_page |
15285 |
op_container_end_page |
15288 |
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1766122883405316096 |