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| Titel |
Early warnings and missed alarms for abrupt monsoon transitions |
| VerfasserIn |
Z. A. Thomas, F. Kwasniok, C. A. Boulton, P. M. Cox, R. T. Jones, T. M. Lenton, C. S. M. Turney |
| 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 ; 11, no. 12 ; Nr. 11, no. 12 (2015-12-08), S.1621-1633 |
| Datensatznummer |
250117486
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| Publikation (Nr.) |
 copernicus.org/cp-11-1621-2015.pdf |
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| Zusammenfassung |
| Palaeo-records from China demonstrate that the East Asian Summer Monsoon
(EASM) is dominated by abrupt and large magnitude monsoon shifts on
millennial timescales, switching between periods of high and weak monsoon
rains. It has been hypothesized that over these timescales, the EASM
exhibits two stable states with bifurcation-type tipping points between
them. Here we test this hypothesis by looking for early warning signals of
past bifurcations in speleothem δ18O records from Sanbao Cave
and Hulu Cave, China, spanning the penultimate glacial cycle. We find that
although there are increases in both autocorrelation and variance preceding
some of the monsoon transitions during this period, it is only immediately
prior to the abrupt monsoon shift at the penultimate deglaciation
(Termination II) that statistically significant increases are detected. To
supplement our data analysis, we produce and analyse multiple model
simulations that we derive from these data. We find hysteresis behaviour in
our model simulations with transitions directly forced by solar insolation.
However, signals of critical slowing down, which occur on the approach to a
bifurcation, are only detectable in the model simulations when the change in
system stability is sufficiently slow to be detected by the sampling
resolution of the data set. This raises the possibility that the early
warning "alarms" were missed in the speleothem data over the period 224–150 kyr and it was only at the monsoon termination that the change in the system
stability was sufficiently slow to detect early warning signals. |
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