 |
| Titel |
Rapid ocean-atmosphere response to Southern Ocean freshening during the last glacial period |
| VerfasserIn |
Christian Turney, Richard Jones, Steven Phipps, Zoë Thomas, Alan Hogg, Peter Kershaw, Christopher Fogwill, Jonathan Palmer, Christopher Bronk Ramsey, Florian Adolphi, Raimund Muscheler, Konrad Hughen, Richard Staff, Mark Grosvenor, Nicholas Golledge, Sune Rasmussen, David Hutchinson, Simon Haberle, Andrew Lorrey, Gretel Boswijk |
| Konferenz |
EGU General Assembly 2017
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250153366
|
| Publikation (Nr.) |
 EGU/EGU2017-18335.pdf |
|
|
|
|
|
| Zusammenfassung |
| Contrasting Greenland and Antarctic temperature trends during the late last glacial period (60,000 to 11,703 years ago) are thought to be driven by imbalances in the rate of formation of North Atlantic and Antarctic Deep Water (the ‘bipolar seesaw’), with cooling in the north leading the onset of warming in the south. Some events, however, appear to have occurred independently of changes in deep water formation but still have a southern expression, implying that an alternative mechanism may have driven some global climatic changes during the glacial. Testing these competing hypotheses is challenging given the relatively large uncertainties associated with correlating terrestrial, marine and ice core records of abrupt change. Here we exploit a bidecadally-resolved 14C calibration dataset obtained from New Zealand kauri (Agathis australis) to undertake high-precision alignment of key climate datasets spanning ~28,400 to 30,400 years ago. We observe no divergence between terrestrial and marine 14C datasets implying limited impact of freshwater hosing on the Atlantic Meridional Overturning Circulation (AMOC). However, an ice-rafted debris event (SA2) in Southern Ocean waters appears to be associated with dramatic synchronous warming over the North Atlantic and contrasting precipitation patterns across the low latitudes. Using a fully coupled climate system model we undertook an ensemble of transient meltwater simulations and find that a southern salinity anomaly can trigger low-latitude temperature changes through barotropic and baroclinic oceanic waves that are atmospherically propagated globally via a Rossby wave train, consistent with contemporary modelling studies. Our results suggest the Antarctic ice sheets and Southern Ocean dynamics may have contributed to some global climatic changes through rapid ocean-atmospheric teleconnections, with implications for past (and future) change. |
|
|
|
|
|
|