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| Titel |
Late Holocene summer temperatures in the central Andes reconstructed from the sediments of high-elevation Laguna Chepical, Chile (32° S) |
| VerfasserIn |
R. Jong, L. Gunten, A. Maldonado, M. Grosjean |
| 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 ; 9, no. 4 ; Nr. 9, no. 4 (2013-08-15), S.1921-1932 |
| Datensatznummer |
250085205
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| Publikation (Nr.) |
 copernicus.org/cp-9-1921-2013.pdf |
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| Zusammenfassung |
High-resolution reconstructions of climate variability that cover the past
millennia are necessary to improve the understanding of natural and
anthropogenic climate change across the globe. Although numerous records are
available for the mid- and high-latitudes of the Northern Hemisphere, global
assessments are still compromised by the scarcity of data from the Southern
Hemisphere. This is particularly the case for the tropical and subtropical
areas. In addition, high elevation sites in the South American Andes may
provide insight into the vertical structure of climate change in the
mid-troposphere. This study presents a 3000 yr-long austral summer (November
to February) temperature reconstruction derived from the 210Pb- and
14C-dated organic sediments of Laguna Chepical
(32°16' S, 70°30' W, 3050 m a.s.l.), a high-elevation
glacial lake in the subtropical Andes of central Chile. Scanning reflectance
spectroscopy in the visible light range provided the spectral index
R570/R630, which reflects the clay mineral content in lake
sediments. For the calibration period (AD 1901–2006), the
R570/R630 data were regressed against monthly meteorological
reanalysis data, showing that this proxy was strongly and significantly
correlated with mean summer (NDJF) temperatures (R3 yr = −0.63,
padj = 0.01). This calibration model was used to make a
quantitative temperature reconstruction back to 1000 BC.
The reconstruction (with a model error RMSEPboot of
0.33 °C) shows that the warmest decades of the past 3000 yr occurred
during the calibration period. The 19th century (end of the Little Ice Age
(LIA)) was cool. The prominent warmth reconstructed for the 18th century,
which was also observed in other records from this area, seems systematic for
subtropical and southern South America but remains difficult to explain.
Except for this warm period, the LIA was generally characterized by cool
summers. Back to AD 1400, the results from this study compare remarkably
well to low altitude records from the Chilean Central Valley and southern
South America. However, the reconstruction from Laguna Chepical does not show
a warm Medieval Climate Anomaly during the 12–13th century, which is
consistent with records from tropical South America. The Chepical record also
indicates substantial cooling prior to 800 BC. This coincides with
well-known regional as well as global glacier advances which have been
attributed to a grand solar minimum. This study thus provides insight into
the climatic drivers and temperature patterns in a region for which currently
very few data are available. It also shows that since ca. AD 1400, long-term
temperature patterns were generally similar at low and high altitudes in
central Chile. |
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