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| Titel |
Effects of dating errors on nonparametric trend analyses of speleothem time series |
| VerfasserIn |
M. Mudelsee, J. Fohlmeister, D. Scholz |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 8, no. 5 ; Nr. 8, no. 5 (2012-10-23), S.1637-1648 |
| Datensatznummer |
250005847
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| Publikation (Nr.) |
 copernicus.org/cp-8-1637-2012.pdf |
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| Zusammenfassung |
| A fundamental problem in paleoclimatology is to take fully into
account the various error sources when examining proxy records with
quantitative methods of statistical time series analysis. Records
from dated climate archives such as speleothems add extra uncertainty
from the age determination to the other sources that consist in
measurement and proxy errors. This paper examines three stalagmite
time series of oxygen isotopic composition (δ18O) from two
caves in western Germany, the series AH-1 from the Atta Cave and the
series Bu1 and Bu4 from the Bunker Cave. These records carry regional
information about past changes in winter precipitation and
temperature. U/Th and radiocarbon dating reveals that they cover the
later part of the Holocene, the past 8.6 thousand years (ka). We
analyse centennial- to millennial-scale climate trends by means of
nonparametric Gasser–Müller kernel regression. Error bands
around fitted trend curves are determined by combining (1) block bootstrap
resampling to preserve noise properties (shape, autocorrelation) of the
δ18O residuals and (2) timescale
simulations (models StalAge and iscam). The timescale error
influences on centennial- to millennial-scale trend estimation are not
excessively large. We find a "mid-Holocene climate double-swing",
from warm to cold to warm winter conditions (6.5 ka to
6.0 ka to 5.1 ka), with warm–cold amplitudes of
around 0.5‰ δ18O; this finding is documented
by all three records with high confidence. We also quantify the
Medieval Warm Period (MWP), the Little Ice Age (LIA) and the current
warmth. Our analyses cannot unequivocally support the conclusion that
current regional winter climate is warmer than that during the MWP. |
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