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Low-frequency and high-frequency changes in temperature and effective humidity during the Holocene in south-central Sweden: implications for atmospheric and oceanic forcings of climate

Seppa, H; Hammarlund, Dan LU and Antonsson, K (2005) In Climate Dynamics 25(2-3). p.285-297
Abstract
An integrated use of independent palaeoclimatological proxy techniques that reflect different components of the climate system provides a potential key for functional analysis of past climate changes. Here we report a 10,000 year quantitative record of annual mean temperature (T-ann), based on pollen-climate transfer functions and pollen-stratigraphical data from Lake Flarken, south-central Sweden. The pollen-based temperature reconstruction is compared with a reconstruction of effective humidity, as reflected by a delta(18)O record obtained on stratigraphy of lacustrine carbonates from Lake Igelsjon, c. 10 km from Lake Flarken, which gives evidence of pronounced changes in effective humidity. The relatively low T-ann, and high effective... (More)
An integrated use of independent palaeoclimatological proxy techniques that reflect different components of the climate system provides a potential key for functional analysis of past climate changes. Here we report a 10,000 year quantitative record of annual mean temperature (T-ann), based on pollen-climate transfer functions and pollen-stratigraphical data from Lake Flarken, south-central Sweden. The pollen-based temperature reconstruction is compared with a reconstruction of effective humidity, as reflected by a delta(18)O record obtained on stratigraphy of lacustrine carbonates from Lake Igelsjon, c. 10 km from Lake Flarken, which gives evidence of pronounced changes in effective humidity. The relatively low T-ann, and high effective humidity as reflected by a low evaporation/inflow ratio suggest a maritime early Holocene climate (10,000-8,300 cat year BP), seemingly incompatible with the highly seasonal solar insolation configuration. We argue that the maritime climate was due to the stronger-than-present zonal flow, enhanced by the high early Holocene sea-surface temperatures in the North Atlantic. The maritime climate mode was disrupted by the abrupt cold event at 8,200 cat year BP, followed at 8,000 cat year BP by a stable Holocene Thermal Maximum. The latter was characterized by T-ann values about 2.5 degrees C higher than at present and markedly dry conditions, indicative of stable summertime anti-cyclonic circulation, possibly corresponding with modern blocking anticyclonic conditions. The last 4,300 year period is characterized by an increasingly cold, moist, and unstable climate. The results demonstrate the value of combining two independent palaeoclimatic proxies in enhancing the reliability, generality, and interpretability of the palaeoclimatic results. Further methodological refinements especially in resolving past seasonal climatic contrasts are needed to better understand the role of different forcing factors in driving millennial-scale climate dynamics. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Climate Dynamics
volume
25
issue
2-3
pages
285 - 297
publisher
Springer
external identifiers
  • wos:000231853700010
  • scopus:25444507725
ISSN
1432-0894
DOI
10.1007/s00382-005-0024-5
language
English
LU publication?
yes
id
8c4ce6f0-a2b6-4778-a052-e3d3b3d2b973 (old id 224565)
date added to LUP
2007-08-16 16:12:56
date last changed
2017-10-22 03:40:56
@article{8c4ce6f0-a2b6-4778-a052-e3d3b3d2b973,
  abstract     = {An integrated use of independent palaeoclimatological proxy techniques that reflect different components of the climate system provides a potential key for functional analysis of past climate changes. Here we report a 10,000 year quantitative record of annual mean temperature (T-ann), based on pollen-climate transfer functions and pollen-stratigraphical data from Lake Flarken, south-central Sweden. The pollen-based temperature reconstruction is compared with a reconstruction of effective humidity, as reflected by a delta(18)O record obtained on stratigraphy of lacustrine carbonates from Lake Igelsjon, c. 10 km from Lake Flarken, which gives evidence of pronounced changes in effective humidity. The relatively low T-ann, and high effective humidity as reflected by a low evaporation/inflow ratio suggest a maritime early Holocene climate (10,000-8,300 cat year BP), seemingly incompatible with the highly seasonal solar insolation configuration. We argue that the maritime climate was due to the stronger-than-present zonal flow, enhanced by the high early Holocene sea-surface temperatures in the North Atlantic. The maritime climate mode was disrupted by the abrupt cold event at 8,200 cat year BP, followed at 8,000 cat year BP by a stable Holocene Thermal Maximum. The latter was characterized by T-ann values about 2.5 degrees C higher than at present and markedly dry conditions, indicative of stable summertime anti-cyclonic circulation, possibly corresponding with modern blocking anticyclonic conditions. The last 4,300 year period is characterized by an increasingly cold, moist, and unstable climate. The results demonstrate the value of combining two independent palaeoclimatic proxies in enhancing the reliability, generality, and interpretability of the palaeoclimatic results. Further methodological refinements especially in resolving past seasonal climatic contrasts are needed to better understand the role of different forcing factors in driving millennial-scale climate dynamics.},
  author       = {Seppa, H and Hammarlund, Dan and Antonsson, K},
  issn         = {1432-0894},
  language     = {eng},
  number       = {2-3},
  pages        = {285--297},
  publisher    = {Springer},
  series       = {Climate Dynamics},
  title        = {Low-frequency and high-frequency changes in temperature and effective humidity during the Holocene in south-central Sweden: implications for atmospheric and oceanic forcings of climate},
  url          = {http://dx.doi.org/10.1007/s00382-005-0024-5},
  volume       = {25},
  year         = {2005},
}