 |
| Titel |
Synchronous signatures of time-irreversibility in Northern and Southern Hemisphere records of last glacial climate and the Holocene |
| VerfasserIn |
Jonathan Donges, Ralf Vogel, Reik Donner, Jürgen Kurths |
| Konferenz |
EGU General Assembly 2015
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250113242
|
| Publikation (Nr.) |
 EGU/EGU2015-13441.pdf |
|
|
|
|
|
| Zusammenfassung |
| The time-reversibility structure of climate time series provides relevant information on the
nature of the underlying processes. A novel statistical test for time-reversibility is employed
that is based on the study of time-directed properties of visibility graphs constructed from
time series and is particularly suitable for the study of irregularly sampled paleoclimate proxy
records. Several ice core, speleothem and lacustrine records of paleoclimate during the late
Pleistocene and Holocene from both Northern and Southern hemispheres are investigated. We
find a consistent and robust signature of time-irreversibility and, hence, nonlinear processes
driving climate dynamics, in the time-interval between approx. 40 and 60 kyr BP (before
present). This signature is most pronounced in ice core records from Greenland and
Antarctica, but also partially apparent in selected speleothem and lacustrine records
from the mid-latitudes and tropics. In contrast, time-reversible climatic dynamics is
detected consistently during the following last glacial maximum period and the
Holocene. These findings suggest that strongly nonlinear (irreversible) climate dynamics
(probably related to the asymmetric saw-tooth-like profile of particularly pronounced
Dansgaard-Oeschger and Heinrich events) between 40–60 kyr BP were followed by
reversible more Holocene-like dynamics appearing well before the actual beginning of the
Holocene. These globally detectable changes in time-reversibility structure may provide
novel insights into climatic dynamics, particularly considering the mechanisms
underlying Dansgaard-Oeschger events during the last glacial and Bond events during the
Holocene, as well as those behind the switch between glacial and interglacial conditions. |
|
|
|
|
|
|