The Late Saalian period (160 - 140 ka): insight on an unusual glaciation
(English)Manuscript (preprint) (Other academic)
This work focuses on the climate evolution over the Late Saalian period (160 - 140 ka) over Eurasia. At this time, the Eurasian ice sheet was larger and higher than during the Last Glacial Maximum. June insolation over the high latitudes presents a large ﬂuctuation over this period: two glacial minima toward 160 and 140 ka and a large insolation peak toward 150 ka. From the geological evidence chronology, it seems clear that the large Eurasian ice sheet already reached its maximum extent at 160 ka. To understand how this ice sheet could survive the 150 ka June insolation maximum, we use several numerical models to simulate the evolution of the vegetation cover, the surface ocean temperatures and ﬁnally the evolution of the Late Saalian climate over the three time slices 140, 150 and 160 ka. Results show that the Late Saalian climate variations are dominated by orbital forcings, responding to a large eccentricity enhancing the precession effect especially at 140 ka. From 160 to 150 ka, the surface ocean exhibits open water conditions in the North At- lantic during summer while sea surface temperature at 140 ka are clearly colder with a large sea ice extent reaching 40◦ N in both the North Atlantic and the North Paciﬁc. This corresponds to a milder climate before 140 ka inducing a larger positive surface mass balance despite the 150 ka insolation peak because of larger precipitation rates. On the contrary, the drastic cooling caused by the astronomical forcing at 140 ka leads to a drier climate cancelling ablation and reducing the accumulation over the ice sheet.
IdentifiersURN: urn:nbn:se:su:diva-29302OAI: oai:DiVA.org:su-29302DiVA: diva2:232273