Early warnings and missed alarms for abrupt monsoon transitions
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 sta...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2015-12-01
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| Series: | Climate of the Past |
| Online Access: | http://www.clim-past.net/11/1621/2015/cp-11-1621-2015.pdf |
| _version_ | 1819240417084833792 |
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| author | Z. A. Thomas F. Kwasniok C. A. Boulton P. M. Cox R. T. Jones T. M. Lenton C. S. M. Turney |
| author_facet | Z. A. Thomas F. Kwasniok C. A. Boulton P. M. Cox R. T. Jones T. M. Lenton C. S. M. Turney |
| author_sort | Z. A. Thomas |
| collection | DOAJ |
| description | 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 δ<sup>18</sup>O 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. |
| first_indexed | 2024-12-23T14:07:41Z |
| format | Article |
| id | doaj.art-3ec76776bb72472f884611189f5afd2c |
| institution | Directory Open Access Journal |
| issn | 1814-9324 1814-9332 |
| language | English |
| last_indexed | 2024-12-23T14:07:41Z |
| publishDate | 2015-12-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Climate of the Past |
| spelling | doaj.art-3ec76776bb72472f884611189f5afd2c2022-12-21T17:44:08ZengCopernicus PublicationsClimate of the Past1814-93241814-93322015-12-0111121621163310.5194/cp-11-1621-2015Early warnings and missed alarms for abrupt monsoon transitionsZ. A. Thomas0F. Kwasniok1C. A. Boulton2P. M. Cox3R. T. Jones4T. M. Lenton5C. S. M. Turney6Climate Change Research Centre and School of Biological, Earth & Environmental Sciences, University of New South Wales, Sydney, NSW 2052, AustraliaCollege of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, EX4 4QF, UKCollege of Life and Environmental Sciences, University of Exeter, Exeter, EX4 4RJ, UKCollege of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, EX4 4QF, UKCollege of Life and Environmental Sciences, University of Exeter, Exeter, EX4 4RJ, UKCollege of Life and Environmental Sciences, University of Exeter, Exeter, EX4 4RJ, UKClimate Change Research Centre and School of Biological, Earth & Environmental Sciences, University of New South Wales, Sydney, NSW 2052, AustraliaPalaeo-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 δ<sup>18</sup>O 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.http://www.clim-past.net/11/1621/2015/cp-11-1621-2015.pdf |
| spellingShingle | Z. A. Thomas F. Kwasniok C. A. Boulton P. M. Cox R. T. Jones T. M. Lenton C. S. M. Turney Early warnings and missed alarms for abrupt monsoon transitions Climate of the Past |
| title | Early warnings and missed alarms for abrupt monsoon transitions |
| title_full | Early warnings and missed alarms for abrupt monsoon transitions |
| title_fullStr | Early warnings and missed alarms for abrupt monsoon transitions |
| title_full_unstemmed | Early warnings and missed alarms for abrupt monsoon transitions |
| title_short | Early warnings and missed alarms for abrupt monsoon transitions |
| title_sort | early warnings and missed alarms for abrupt monsoon transitions |
| url | http://www.clim-past.net/11/1621/2015/cp-11-1621-2015.pdf |
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