Terrestrial climate variability and seasonality changes in the Mediterranean region between 15 000 and 4000 years BP deduced from marine pollen records

Pollen-based climate reconstructions were performed on two high-resolution pollen marines cores from the Alboran and Aegean Seas in order to unravel the climatic variability in the coastal settings of the Mediterranean region between 15 000 and 4000 years BP (the Lateglacial, and early to mid-Holocene). The quantitative climate reconstructions for the Alboran and Aegean Sea records focus mainly on the reconstruction of the seasonality changes (temperatures and precipitation), a crucial parameter in the Mediterranean region. This study is based on a multi-method approach comprising 3 methods: the Modern Analogues Technique (MAT), the recent Non-Metric Multidimensional Scaling/Generalized Additive Model method (NMDS/GAM) and Partial Least Squares regression (PLS). The climate signal inferred from this comparative approach confirms that cold and dry conditions prevailed in the Mediterranean region during the Oldest and Younger Dryas periods, while temperate conditions prevailed during the Bølling/Allerød and the Holocene. Our records suggest a West/East gradient of decreasing precipitation across the Mediterranean region during the cooler Late-glacial and early Holocene periods, similar to present-day conditions. Winter precipitation was highest during warm intervals and lowest during cooling phases. Several short-lived cool intervals (i.e. Older Dryas, another oscillation after this one (GI-1c2), Gerzensee/Preboreal Oscillations, 8.2 ka event, Bond events) connected to the North Atlantic climate system are documented in the Alboran and Aegean Sea records indicating that the climate oscillations associated with the successive steps of the deglaciation in the North Atlantic area occurred in both the western and eastern Mediterranean regions. This observation confirms the presence of strong climatic linkages between the North Atlantic and Mediterranean regions

Junior Students’ with Hearing Impairment Psychological Correction of Learning Motivation Development

У статті розглянуто основні методологічні принципи, методи, етапи корекційного процесу. Обґрунтовано використання гуманістичного підходу до корекції мотиваційної сфери учіння та підібрано комплекс корекційних завдань для розвитку цієї сфери в молодших школярів із порушеннями слуху. The article presents basic methodological principles, methods, main stages of correctional process. A humanitarian approach to learning motivation development correction has been grounded and a complex of correctional tasks for junior students with hearing impairment has been selected

New key-tools for pollen identification in research and education

Pollen ID offers a free and easy access to various palynological information and compiles in the same web-space a pollen database and different services through a friendly user interface. Pollen ID proposes, or will propose, pollen and plant descriptions, terminology learning with an illustrated glossary and interactive images, identification keys, pollen analysis, pollen diagram construction, links with vegetation and climate data. The Pollen ID project is presently restricted to the European and Mediterranean geographical area, but it will be extended to other regions as well. This project is still in progress; its content and user interface – presently in French - will be soon available in English. In its final shape, the Pollen ID project will include palynological applications such as pollen determination tests, several original pollen analysis exercises with representations in diagrams and an easy interpretation of vegetation and climate. Pollen ID is accessible on http://lisupmc. snv.jussieu.fr/pollen/

The establishment of the agricultural landscape of central Sicily between the Middle Neolithic and the beginning of the Iron Age

The possible co-variation of human occupation and vegetation from the Middle Neolithic to the beginning of the Iron Age (7.5–2.8 ka BP) in Central Sicily in the context of the central Mediterranean between Middle and Late Holocene are analysed in this paper to provide new insights on Sicilian prehistoric demography. The demographic and economic trends during these millennia were reconstructed using archaeological, Accelerator Mass Spectrometry 14C dates, palynological, archaeobotanical, and zooarchaeological data from the northern, central, and southern sectors of Central Sicily through a diachronic comparison with variation in Arboreal Pollen, Anthropogenic Pollen Indicators, Olea-Juglans-Castanea pollen, microcharcoals, and Sporormiella from four pollen cores from sites in different ecosystems. A very significant spread of farming activities was found at the end of the Neolithic, together with an apparent demographic gap during the Middle Copper Age, and the emergence of agricultural landscapes at the end of the Copper Age associated with a striking increase in population. A combination of cultural and climatic changes during the late phase of the Bronze Age resulted in a subsequent overall decrease in population

Tracking atmospheric and riverine terrigenous supplies variability during the last glacial and the Holocene in central Mediterranean

International audienceA multiproxy study coupling mineralogical, grain size and geochemical approaches was used to tentatively retrace eolian and fluvial contributions to sedimentation in the Sicilian Tunisian Strait since the last glacial. The eolian supply is dominant over the whole interval, excepted during the sapropel Si when riverine contribution apparently became significant. Saharan contribution increased during the B011ing Allerod, evidencing the persistence of aridity over North Africa although the northern Mediterranean already experienced moister and warmer conditions. The Younger Dryas is marked by proximal dust inputs, highlighting intense regional eolian activity. A southward migration of dust provenance toward Sahel occurred at the onset of the Holocene, likely resulting from a southward position of the Inter Tropical Convergence Zone that was probably associated with a large-scale atmospheric reorganization. Finally, a peculiar high terrigenous flux associated with drastic modifications of the mineralogical and geochemical sediment signature occurred during the sapropel 51, suggesting the propagation of fine particles derived from major floodings of the Nile River resulting from enhanced rainfall on northeastern Africa and their transportation across the Sicilian Tunisian Strait by intermediate water masses

Holocene climate variability of the Western Mediterranean: surface water dynamics inferred from calcareous plankton assemblages

A high-resolution study (centennial scale) has been performed on the calcareous plankton assemblage of the Holocene portion of the Ocean Drilling Program Site 976 (Alboran Sea) with the aim to identify the main changes in the surface water dynamic. The dataset also provided a seasonal foraminiferal sea surface water temperatures (SSTs), estimated using the modern analog technique SIMMAX 28, and it was compared with available geochemical and pollen data at the site. Three main climate shifts were identified as (1) the increase in abundance of Syracosphaera spp. and Turborotalita quinqueloba marks the early Holocene humid phase, during maximum summer insolation and enhanced river runoff. It is concomitant with the expansion of Quercus, supporting high humidity on land. It ends at 8.2 ka, registering a sudden temperature and humidity reduction; (2) the rise in the abundances of Florisphaera profunda and Globorotalia inflata, at ca. 8 ka, indicates the development of the modern geostrophic front, gyre circulation, and of a deep nutricline following the sea-level rise; and (3) the increase of small Gephyrocapsa and Globigerina bulloides at 5.3 ka suggests enhanced nutrient availability in surface waters, related to more persistent wind-induced upwelling conditions. Relatively higher winter SST in the last 3.5 ka favored the increase of Trilobatus sacculifer, likely connected to more stable surface water conditions. Over the main trends, a short-term cyclicity is registered in coccolithophore productivity during the last 8 ka. Short periods of increased productivity are in phase with Atlantic waters inflow, and more arid intervals on land. This cyclicity has been related with periods of positive North Atlantic Oscillation (NAO) circulations. Spectral analysis on coccolithophore productivity confirms the occurrence of millennial-scale cyclicity, suggesting an external (i.e. solar) and an internal (i.e. atmospheric/oceanic) forcing.Geoscience PhD scholarship, Universita degli Studi di BariPotenziamento Strutturale dell'Universita degli Studi di Bari, Laboratorio per lo Sviluppo Integrato delle Scienze e delle Tecnologie dei Materiali Avanzati e per dispositivi innovativi (SISTEMA) [PONa3_00369]Fundacao para a Ciencia e a Tecnologia (FCT)Portuguese Foundation for Science and TechnologyEuropean Commission [SFRH/BPD/111433/2015]info:eu-repo/semantics/submittedVersio

Corrigendum to “Pollen-based paleoenvironmental and paleoclimatic change at Lake Ohrid (south-eastern Europe) during the past 500 ka” published in Biogeosciences, 13, 1423–1437, 2016

In this corrigendum we report an updated pollen record from the Lake Ohrid DEEP site spanning the past 500 ka whereby we have reprocessed and re-analyzed 104 samples affected by chemical procedure problems that occurred in one palynological laboratory. Firstly, these samples were affected by the use of wrong containers, causing in- adequate settling of particles at the set centrifuging speed. Secondly, HCl and HF treatments were combined without the prescribed intermediate centrifuging and decanting steps. The inaccuracy in the protocol resulted in the loss of smaller pollen grains and in the overrepresentation of bisaccate ones in most of the re-analyzed samples. We therefore provide an updated set of figures with the new data and have revised the description of the results, discussion and conclusions re- ported in Sadori et al. (2016) where necessary. We stress that the majority of the original results and conclusions remain valid, while the records’ reliability and resolution have improved as 12 samples that had been omitted in the original study because of low count sums are now included in the revised dataset (Sadori et al., 2018)

Deglacial and Holocene vegetation and climatic changes in the southern Central Mediterranean from a direct land–sea correlation

International audienceDespite a large number of studies, the long-term and millennial to centennial-scale climatic variability in the Mediterranean region during the last deglaciation and the Holocene is still debated, including in the southern Central Mediterranean. In this paper, we present a new marine pollen sequence (core MD04-2797CQ) from the Siculo-Tunisian Strait documenting the regional vegetation and climatic changes in the southern Central Mediterranean during the last deglaciation and the Holocene. The MD04-2797CQ marine pollen sequence shows that semi-desert plants dominated the vegetal cover in the southern Central Mediterranean between 18.2 and 12.3 ka cal BP, indicating prevailing dry conditions during the deglaciation, even during the Greenland Interstadial (GI)-1. Across the transition Greenland Stadial (GS)-1 -Holocene, Asteraceae-Poaceae steppe became dominant till 10.1 ka cal BP. This record underlines with no chronological ambiguity that even though temperatures increased, deficiency in moisture availability persisted into the early Holocene. Temperate trees and shrubs with heath underbrush or maquis expanded between 10.1 and 6.6 ka, corresponding to Sapropel 1 (S1) interval, while Mediterranean plants only developed from 6.6 ka onwards. These changes in vegetal cover show that the regional climate in southern Central Mediterranean was wetter during S1 and became drier during the mid-to late Holocene. Wetter conditions during S1 were likely due to increased winter precipitation while summers remained dry. We suggest, in agreement with published modeling experiments, that the early Holocene increased melting of the Laurentide Ice Sheet in conjunction with weak winter insolation played a major role in the development of winter precipitation maxima in the Mediterranean region in controlling the strength and position of the North Atlantic storm track. Finally, our data provide evidence for centennial-scale vegetation and climatic changes in the southern Central Mediterranean. During the wet early Holocene, alkenone-derived cooling episodes are synchronous with herbaceous composition changes that indicate muted changes in precipitation. In contrast, enhanced aridity episodes, as detected by strong reduction in trees and shrubs, are recorded during the mid-to late Holocene. We show that the impact of the Holocene cooling events on the Mediterranean hydroclimate depend on baseline climate states, i.e. insolation and ice sheet extent, shaping the response of the mid-latitude atmospheric circulation

Precipitation changes in the Mediterranean basin during the Holocene from terrestrial and marine pollen records: a model–data comparison

Climate evolution of the Mediterranean region during the Holocene exhibits strong spatial and temporal variability. The spatial differentiation and temporal variability, as evident from different climate proxy datasets, has remained notoriously difficult for models to reproduce. In light of this complexity, we examine the previously described evidence for (i) opposing northern and southern precipitation regimes during the Holocene across the Mediterranean basin, and (ii) an east-to-west precipitation gradient or dipole during the early Holocene, from a wet eastern Mediterranean to dry western Mediterranean. Using quantitative climate information from marine and terrestrial pollen archives, we focus on two key time intervals, the early to mid-Holocene (8000 to 6000 cal yrs BP) and the late Holocene (4000 to 2000 yrs BP), in order to test the above mentioned hypotheses on a Mediterranean-wide scale. Palynologically derived climate information is compared with the output of regional-scale climate-model simulations for the same time intervals. Quantitative pollen-based precipitation estimates were generated along a longitudinal gradient from the Alboran (West) to the Aegean Sea (East); they are derived from terrestrial pollen records from Greece, Italy and Malta as well as from pollen records obtained from marine cores. Because seasonality represents a key parameter in Mediterranean climates, special attention was given to the reconstruction of season-specific climate information, notably summer and winter precipitation. The reconstructed climatic trends corroborate a previously described north-south partition of precipitation regimes during the Holocene. During the early Holocene, relatively wet conditions occurred in the south-central and eastern Mediterranean region, while drier conditions prevailed from 45° N northwards. These patterns reversed during the late Holocene, with a wetter northern Mediterranean region and drier conditions in the east and south. More sites from the northern part of the Mediterranean basin are needed to further substantiate these observations. With regard to the existence of a west-east precipitation dipole during the Holocene, our pollen-based climate data show that the strength of this dipole is strongly linked to the seasonal parameter reconstructed: Early Holocene summers show a clear east-to-west gradient, with summer precipitation having been highest in the central and eastern Mediterranean and lowest over the western Mediterranean. In contrast, winter precipitation signals are less spatially coherent. A general drying trend occurred from the early to the late Holocene; particularly in the central and eastern Mediterranean. However, summer precipitation in the east remained above modern values, even during the late Holocene interval. Pollen-inferred precipitation estimates were compared to regional-scale climate modelling simulations based on the HadAM3 GCM coupled to the dynamic HadSM3 and the high-resolution regional HadRM3 models. Climate model outputs and pollen-inferred precipitation estimates show remarkably good overall correspondence, although many simulated patterns are of marginal statistical significance. Nevertheless, models weakly support an east to west division in summer precipitation and there are suggestions that the eastern Mediterranean experienced wetter summer and winter conditions during the early Holocene and wetter summer conditions during the late Holocene. The extent to which summer monsoonal precipitation may have existed in the southern and eastern Mediterranean during the mid-Holocene remains an outstanding question; our model, consistent with other global models, does not suggest an extension of the African monsoon into the Mediterranean. Given the difficulty in modelling future climate change in Southern Europe, more simulations based on high resolution global models and very high resolution regional downscaling, perhaps even including transient simulations, are required to fully understand the patterns of change in winter and summer circulation patterns over the Mediterranean regio