Dansgaard–Oeschger-like events of the penultimate climate cycle: the loess point of view

Abstract

Abstract. The global character of the millennial-scale climate variability associated with the Dansgaard–Oeschger (DO) events in Greenland has been well-established for the last glacial cycle. Mainly due to the sparsity of reliable data, however, the spatial coherence of corresponding variability during the penultimate cycle is less clear. New investigations of European loess records from Marine Isotope Stage (MIS) 6 reveal the occurrence of alternating loess intervals and paleosols (incipient soil horizons), similar to those from the last climatic cycle. These paleosols are correlated, based on their stratigraphical position and numbers as well as available optically stimulated luminescence (OSL) dates, with interstadials described in various Northern Hemisphere records and in GLt_syn, the synthetic 800 kyr record of Greenland ice core δ18O. Therefore, referring to the interstadials described in the record of the last climate cycle in European loess sequences, the four MIS 6 interstadials can confidently be interpreted as DO-like events of the penultimate climate cycle. Six more interstadials are identified from proxy measurements performed on the same interval, leading to a total of 10 interstadials with a DO-like event status. The statistical similarity between the millennial-scale loess–paleosol oscillations during the last and penultimate climate cycle provides direct empirical evidence that the cycles of the penultimate cycle are indeed of the same nature as the DO cycles originally discovered for the last glacial cycle. Our results thus imply that their underlying cause and global imprint were characteristic of at least the last two climate cycles.

A Jurassic record encodes an analogous Dansgaard–Oeschger climate periodicity

“…Ice-core records from the Greenland, and deep-sea sediment records from the North Atlantic Ocean highlight these prominent DO glacial events. Paleoclimatic studies have now shown that the 1500-year climate cycle is no longer restricted to the North Atlantic Ocean of the last glacial period 3 . The 1500-year cycle is documented in both hemispheres, in other oceans and in continents, such as in lake and river deposits 4 – 6 , in pollen fossils 7 , in stalagmite proxy records 8 , and in loess–paleosol deposits 3 .…”

Evidence for strong relations between the upper Tagus loess formation (central Iberia) and the marine atmosphere off the Iberian margin during the last glacial period

“…Phases of loess deposition are generally linked to harsh environmental conditions. In contrast, phases showing an interruption of loess deposition as indicated by surface exposure and the initiation of soil forming processes are generally assumed to indicate more favorable environmental conditions that often accompanied Greenland interstadials (GI, e.g., Fischer et al, 2021) and are therefore interpreted as D-O-like events (Rousseau et al, 2017(Rousseau et al, , 2020. Based on variations of NGRIP δ 18 O and dust concentration, Rousseau et al (2017) calculated onset and duration of the various GIs in the Northern Hemisphere during the last glacial period and found a strong conformity between higher GI duration and more intense soil development in northwestern Europe as indicated by loess-paleosol sequences (LPS).…”

Late Pleistocene Climate and Dust Source From the Mobarakabad Loess–Paleosol Sequence, Northern Foothills of the Alborz Mountains, Northern Iran

“…Loess sediment in the mid-latitude of Eurasia provides an excellent sedimentary archive for understanding past climate and environmental changes in the continental interior (e.g., Rousseau et al, 2017Rousseau et al, , 2020Fenn et al, 2020;Fitzsimmons et al, 2020;Költringer et al, 2020;Song et al, 2021). In northern Iran, loess deposits are found in the so-called Northern Iranian Loess Plateau (NILP) and along the northern foothills of the Alborz Mountain range (NFAM).…”