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| Titel |
Madagascar corals reveal a multidecadal signature of rainfall and river runoff since 1708 |
| VerfasserIn |
C. A. Grove, J. Zinke, F. Peeters, W. Park, T. Scheufen, S. Kasper, B. Randriamanantsoa, M. T. McCulloch, G.-J. A. Brummer |
| 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. 2 ; Nr. 9, no. 2 (2013-03-13), S.641-656 |
| Datensatznummer |
250018011
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| Publikation (Nr.) |
 copernicus.org/cp-9-641-2013.pdf |
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| Zusammenfassung |
| Pacific Ocean sea surface temperatures (SST) influence
rainfall variability on multidecadal and interdecadal timescales in concert
with the Pacific Decadal Oscillation (PDO) and Interdecadal Pacific
Oscillation (IPO). Rainfall variations in locations such as Australia and North
America are therefore linked to phase changes in the PDO. Furthermore,
studies have suggested teleconnections exist between the western Indian
Ocean and Pacific Decadal Variability (PDV), similar to those observed on
interannual timescales related to the El Niño Southern Oscillation
(ENSO). However, as instrumental records of rainfall are too short and
sparse to confidently assess multidecadal climatic teleconnections, here we
present four coral climate archives from Madagascar spanning up to the past
300 yr (1708–2008) to assess such decadal variability. Using spectral
luminescence scanning to reconstruct past changes in river runoff, we
identify significant multidecadal and interdecadal frequencies in the coral
records, which before 1900 are coherent with Asian-based PDO
reconstructions. This multidecadal relationship with the Asian-based PDO
reconstructions points to an unidentified teleconnection mechanism that
affects Madagascar rainfall/runoff, most likely triggered by multidecadal
changes in North Pacific SST, influencing the Asian Monsoon circulation. In
the 20th century we decouple human deforestation effects from rainfall-induced
soil erosion by pairing luminescence with coral geochemistry.
Positive PDO phases are associated with increased Indian Ocean temperatures
and runoff/rainfall in eastern Madagascar, while precipitation in southern
Africa and eastern Australia declines. Consequently, the negative PDO phase
that started in 1998 may contribute to reduced rainfall over eastern
Madagascar and increased precipitation in southern Africa and eastern
Australia. We conclude that multidecadal rainfall variability in Madagascar
and the western Indian Ocean needs to be taken into account when considering
water resource management under a future warming climate. |
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