Relación entre la evolución sedimentaria de la laguna de Gallocanta (Cordillera Ibérica, NE de España) y la historia de la vegetación de su cuenca durante el Cuaternario reciente

The analysis of the facies in the sediments from Gallocanta Lake allows the identification of three stages of sedimentation. The lowest stage related with the late Pleistocene corresponds with distal alluvial areas, the second stage reflects a shallow carbonated lake probably developed from the beginning of the Holocene to the Middle Age and, the last one corresponds to a saline-carbonated lake formed in the last centuries. In the alluvial facies the pollen concentration is very low. The following stages are related with different types of pollen assemblages. The stage of a shallow carbonated lake is associated with the development of a deciduous and evergreen Quercus forest in the basin and represents the maximum water depth, 4 to 10 meters, of the Gallocanta Lake. This period The last stage of saline-carbonated lake, dated at 1900 AD, coincides with the maximum phase of Olea cultivation contemporaneous with the decrease of the lake level. The depth of the water was between 0 and 2 m. The drying out of the Gallocanta lake coincides with the lake level lowering of other lakes in the Ebro basin suggesting a regional driving-factor (climatic and/or anthropic) as the main responsible for the observed desiccation of the last century

Moist and warm conditions in Eurasia during the last glacial of the Middle Pleistocene Transition

The end of the Middle Pleistocene Transition (MPT, ~ 800-670 thousand years before present, ka) was characterised by the emergence of large glacial ice-sheets associated with anomalously warm North Atlantic sea surface temperatures enhancing moisture production. Still, the direction and intensity of moisture transport across Eurasia towards potential ice-sheets is poorly constrained. To reconstruct late MPT moisture production and dispersal, we combine records of upper ocean temperature and pollen-based Mediterranean forest cover, a tracer of westerlies and precipitation, from a subtropical drill-core collected off South-West Iberia, with records of East Asia summer monsoon (EASM) strength and West Pacific surface temperatures, and model simulations. Here we show that south-western European winter precipitation and EASM strength reached high levels during the Marine Isotope Stage 18 glacial. This anomalous situation was caused by nearly-continuous moisture supply from both oceans and its transport to higher latitudes through the westerlies, likely fuelling the accelerated expansion of northern hemisphere ice-sheets during the late MPT. © 2023, The Author(s).This research used samples collected during the Expedition no. 339 “Mediterranean Outflow“ of the Integrated Ocean Drilling Program (IODP). M.F.S.G. acknowledges funding from the GPR Human Past (University of Bordeaux). A.B. thanks Deutsche Forschungsgemeinschaft (DFG), project BA 3809/8. C.Z. acknowledges funding from IODP France and J.M.P.-M. from the Junta de Castilla y León and the European Regional Development Fund (Grant CLU-2019-03). T.R. acknowledges funding from FCT through projects Hydroshift (PTDC/CTA-CLI/4297/2021), WarmWorld (PTDC/CTA-GEO/29897/2017), UIDB/04326/2020, UIDP/04326/2020, LA/P/0101/2020 and EMSO-PT (POCI-01-0145-FEDER-022157). We thank Vincent Hanquiez for drawing Fig. and Ludovic Devaux for pollen sample preparation

Variabilité climatique pendant les périodes interglaciaires du Pléistocène moyen dans le sud-ouest de l'Europe

An atypical short-lived terrestrial interglacial in SW Iberia during MIS 9e due to a millennial-scale climatic change is not confirmed. High latitude warming induced by both strong GHG and insolation forcing may be associated with a different regional climatic expression in regions sensitive to climate change in terms of water availablity. Difference in forest expansion and precipitation in SW Iberia between MIS9 and MIS 5 mainly result from the contribution of insolation

Saharan dust transport and high-latitude glacial climate variability: the Alboran Sea record

status: publishe

Western Mediterranean vegetation and climate dynamics during the best astronomical analogues of the Holocene: evidence from a model–data comparison

The suitability of MIS 11c and MIS 19c as analogues of our present interglacial and its natural evolution is still debated. Here we examine the regional expression of the Holocene and its orbital analogues over SW Iberia using a model–data comparison approach. Regional tree fraction and climate based on snapshot and transient experiments using the LOVECLIM model are evaluated against the terrestrial–marine profiles from Site U1385 documenting the regional vegetation and climatic changes. The pollen-based reconstructions show a larger forest optimum during the Holocene compared to MIS 11c and MIS 19c, putting into question their analogy in SW Europe. Pollen-based and model results indicate reduced MIS 11c forest cover compared to the Holocene primarily driven by lower winter precipitation, which is critical for Mediterranean forest development. Decreased precipitation was possibly induced by the amplified MIS 11c latitudinal insolation and temperature gradient that shifted the westerlies northwards. In contrast, the reconstructed lower forest optimum at MIS 19c is not reproduced by the simulations probably due to the lack of Eurasian ice sheets and its related feedbacks in the model. Transient experiments with time-varying insolation and CO2 reveal that the SW Iberian forest dynamics over the interglacials are mostly coupled to changes in winter precipitation mainly controlled by precession, CO2 playing a negligible role. Model simulations reproduce the observed persistent vegetation changes at millennial time scales in SW Iberia and the strong forest reductions marking the end of the interglacial “optimum”

25. Climate variability of the last five isotopic interglacials: Direct land-sea-ice correlation from the multiproxy analysis of North-Western Iberian margin deep-sea cores

International audienc

Regional expression of the MIS9e interglacial in southwestern Europe

Intensity and regional expression of past interglacial periods are among the challenging questions on natural interglacial variability. Model experiments show that some interglacials of the last 800 kyr, such as MIS 9 and 5 interglacials, stand out by the strongest warming at high latitudes resulting from important insolation and greenhouse gas forcing while weak or no temperature difference with other interglacials is simulated at mid-latitudes. Processes leading to glacial inceptions are also debated. Millennialscale climate variability during ice volume minima was proposed to play a predominant role in prescribing interglacial duration. A major evidence of that process was given by the pollen record from the SW Iberian margin MD01-2443 showing an early collapse of the Mediterranean forest in SW Europe during MIS 9e likely due to an abrupt climate change. This terrestrial interglacial appears however anomalously short-lasting as compared to other records from the southern Europe and North Atlantic. The IODP site U1385 from the SW Iberian margin enables to revisit the regional signature of the MIS 9 interglacial in southwestern Europe. We will present new pollen data to characterize the Iberian vegetation and climate changes during MIS9e. Our results display, in agreement with the MD01-2443 pollen record, a short-lasting maximal forest expansion during the early MIS9e but a persisting forest over the entire MIS9e. Comparisons with MIS 5 pollen data from the Iberian margin and model simulations confirm that in contrast to high latitudes, interglacial climate in southern Europe, in particular precipitation, mainly result from the contribution of insolation