Downscaled land surface temperatures obtained by a particle smoothing approach, with links to NetCDF files

This dataset contains continuous time series of land surface temperature (LST) at spatial resolution of 300m around the 12 experimental sites of the PAGE21 project (grant agreement number 282700, funded by the EC seventh Framework Program theme FP7-ENV-2011). This dataset was produced from hourly LST time series at 25km scale, retrieved from SSM/I data (André et al., 2015, doi:10.1016/j.rse.2015.01.028) and downscaled to 300m using a dynamic model and a particle smoothing approach. This methodology is based on two main assumptions. First, LST spatial variability is mostly explained by land cover and soil hydric state. Second, LST is unique for a land cover class within the low resolution pixel. Given these hypotheses, this variable can be estimated using a land cover map and a physically based land surface model constrained with observations using a data assimilation process. This methodology described in Mechri et al. (2014, doi:10.1002/2013JD020354) was applied to the ORCHIDEE land surface model (Krinner et al., 2005, doi:10.1029/2003GB002199) to estimate prior values of each land cover class provided by the ESA CCI-Land Cover product (Bontemps et al., 2013) at 300m resolution . The assimilation process (particle smoother) consists in simulating ensemble of LST time series for each land cover class and for a large number of parameter sets. For each parameter set, the resulting temperatures are aggregated considering the grid fraction of each land cover and compared to the coarse observations. Miniminizing the distance between the aggregated model solutions and the observations allow us to select the simulated LST and the corresponding parameter sets which fit the observations most closely. The retained parameter sets are then duplicated and randomly perturbed before simulating the next time window. At the end, the most likely LST of each land cover class are estimated and used to reconstruct LST maps at 300m resolution using ESA CCI-Land Cover. The resulting temperature maps on which ice pixels were masked, are provided at daily time step during the nine-year analysis period (2000-2009).

The late Pliocene pollen record of ODP Site 108-658 off Cape Blanc, Atlantic Ocean

A 200 m long marine pollen record from ODP Site 658 (21°N, 19°W) reveals cyclic fluctuations in vegetation and continental climate in northwestern Africa from 3.7 to 1.7 Ma. These cycles parallel oxygen isotope stages. Prior to 3.5 Ma, the distribution of tropical forests and mangrove swamps reached Cape Blanc, 5°N of the present distribution. Between 3.5 and 2.6 Ma, forests occurred at this latitude during irregular intervals and nearly disappeared afterwards. Likewise, a Saharan paleoriver flowed continuously until isotope Stage 134 (3.35 Ma). When river discharge ceased, wind transport of pollen grains prevailed over fluvial transport. Pollen indicators of trade winds gradually increased between 3.3 and 2.5 Ma. A strong aridification of the climate of northwestern Africa occurred during isotope Stage 130 (3.26 Ma). Afterwards, humid conditions reestablised followed by another aridification around 2.7 Ma. Repetitive latitudinal shifts of vegetation zones ranging from wooded savanna to desert flora dominated for the first time between between 2.6 and 2.4 Ma as a response to the glacial stages 104, 100 and 98. Although climatic conditions, recorded in the Pliocene, were not as dry as those of the middle and Late Pleistocene, latitudinal vegetation shifts near the end of the Pliocene resembled those of the interglacial-glacial cycles of the Brunhes chron.

Pollen content and radiocarbon ages of profile Delorett, Austria

A pollen profile from the highest known peatbog in the Alps is presented. The peatbog started to grow about 8000 years ago and over the last 5000 years. The influence of man on the vegetation is documented. Before the beginning of the bronze age pasturing started.

Results of a sediment profile and water analyses from Lake Hancza in northeastern Poland

We investigated the sedimentary record of Lake Hancza (northeastern Poland) using a multi-proxy approach, focusing on early to mid-Holocene climatic and environmental changes. AMS 14C dating of terrestrial macrofossils and sedimentation rate estimates from occasional varve thickness measurements were used to establish a chronology. The onset of the Holocene at c. 11600 cal. a BP is marked by the decline of Lateglacial shrub vegetation and a shift from clastic-detrital deposition to an autochthonous sedimentation dominated by biochemical calcite precipitation. Between 10000 and 9000 cal. a BP, a further environmental and climatic improvement is indicated by the spread of deciduous forests, an increase in lake organic matter and a 1.7% rise in the oxygen isotope ratios of both endogenic calcite and ostracod valves. Rising d18O values were probably caused by a combination of hydrological and climatic factors. The persistence of relatively cold and dry climate conditions in northeastern Poland during the first one and a half millennia of the Holocene could be related to a regional eastern European atmospheric circulation pattern. Prevailing anticyclonic circulation linked to a high-pressure cell above the retreating Scandinavian Ice Sheet might have blocked the influence of warm and moist Westerlies and attenuated the early Holocene climatic amelioration in the Lake Hancza region until the final decay of the ice sheet.

Carbonate system during the May 2013 MedSeA cruise

Most global ocean models are based on the assumption of a "steady state" ocean. Here, we investigate the validation of this hypothesis for the anthropized Mediterranean Sea. In order to do so, we calculated the mixing coefficients of the water masses detected in this sea via an optimum multiparameter analysis referred to as the MIX approach, using data from the BOUM (2008) and MedSeA (2013) cruises. The comparison of the mixing coefficients of each water mass, between 2008 and 2013, indicates that some of their proportions have significantly changed. Surface water mass proportions did not change significantly (Delta0.05-0.1), while intermediate and deep water mass mixing coefficients of both Eastern and Western basins were significantly modified (~Delata 0.35). This study clearly shows that the Mediterranean seawater is not in a "steady state".

Palynology on lake sediments from the Pyrenees

A multi-proxy palaeoecological investigation including pollen, plant macrofossil, radiocarbon and sedimentological analyses, was performed on a small mountain lake in the Eastern Pyrenees. This has allowed the reconstruction of: (1) the vegetation history of the area based on five pollen diagrams and eight AMS14C dates and (2) the past lake-level changes, based on plant macrofossil, lithological and pollen analysis of two stratigraphical transects correlated by pollen analysis. The palaeolake may have appeared before the Younger Dryas; the lake-level was low and the vegetation dominated by cold steppic grasslands. The lake-level rose to its highest level during the Holocene in the Middle Atlantic (at ca. 5060±45 b.p.). Postglacial forests (Quercetum mixtum and Abieto-Fagetum) developed progressively in the lower part of the valley, while dense Pinus uncinata forests rapidly invaded the surroundings of the mire and remained the dominant local vegetation until present. The observed lowering of the lake levels during the Late Atlantic and the Subboreal (from 5060 ± B.P. to 3590±40 b.p.) was related to the overgrowth of the mire. The first obvious indications of anthropogenic disturbances of the vegetation are recorded at the Atlantic/Subboreal boundary as a reduction in the forest component, which has accelerated during the last two millennia.

Pollen record and age determinations of a profile at Cape Mamontov Klyk, Siberia

Non-glaciated Arctic lowlands in north-east Siberia were subjected to extensive landscape and environmental changes during the Late Quaternary. Coastal cliffs along the Arctic shelf seas expose terrestrial archives containing numerous palaeoenvironmental indicators (e.g., pollen, plant macro-fossils and mammal fossils) preserved in the permafrost. The presented sedimentological (grain size, magnetic susceptibility and biogeochemical parameters), cryolithological, geochronological (radiocarbon, accelerator mass spectrometry and infrared-stimulated luminescence), heavy mineral and palaeoecological records from Cape Mamontov Klyk record the environmental dynamics of an Arctic shelf lowland east of the Taymyr Peninsula, and thus, near the eastern edge of the Eurasian ice sheet, over the last 60 Ky. This region is also considered to be the westernmost part of Beringia, the non-glaciated landmass that lay between the Eurasian and the Laurentian ice caps during the Late Pleistocene. Several units and subunits of sand deposits, peat-sand alternations, ice-rich palaeocryosol sequences (Ice Complex) and peaty fillings of thermokarst depressions and valleys were presented. The recorded proxy data sets reflect cold stadial climate conditions between 60 and 50 Kya, moderate inderstadial conditions between 50 and 25 Kya and cold stadial conditions from 25 to 15 Kya. The Late Pleistocene to Holocene transition, including the Allerød warm period, the early to middle Holocene thermal optimum and the late Holocene cooling, are also recorded. Three phases of landscape dynamic (fluvial/alluvial, irregular slope run-off and thermokarst) were presented in a schematic model, and were subsequently correlated with the supraregional environmental history between the Early Weichselian and the Holocene.

Miocene pollen of ODP Leg 127 sites

Pollen floras were obtained from Miocene sediments recovered at four sites drilled during Ocean Drilling Program Leg 127. The local pollen floras of each site were correlated to the standard pollen zones of northeast Japan by using the concept of the essential members for each pollen zone. At Site 797, the complete floral range was obtained for recognition of the NP2 zone and the pollen components of the NP1 zone were also clarified continuously. The ages of the boundaries between pollen zones NP4/NP3, NP3/NP2, and NP2/NP1 are estimated to be about 7 Ma, 13 Ma, and 17-18.5 Ma, respectively. Even in the same pollen zone, the ratios of major pollen taxa vary with the location. This variation is expressed on maps representing two different times during the Miocene.

Palynological and stratigraphic record from Löddigsee in Mecklenburg-Vorpommern, Germany

A Late Pleistocene and Holocene sediment core from the nowadays terrestrialised portion of the Löddigsee in Southern Mecklenburg, Germany was palynologically investigated. The lake is situated in the rarely investigated Young moraine area at the transition from the Weichselian to the Saalian glaciation. The high-resolution pollen diagram contributes to the establishment of the north-eastern German Late Pleistocene pollen stratigraphy. The vegetation distribution pattern after the end of the Weichselian is in good agreement with other studies from North-eastern Germany, but also has its own characteristics. The Holocene vegetation development reveals features from the north-eastern and north-western German lowlands. A special focus was laid on the environmental history of the two settlements on an island within the lake (Late Neolithic and Younger Slavic period), which were preserved under moist conditions. Both settlements were constructed during a period of low lake level. Although there is evidence of agriculture in the area during the respective periods, the two island settlements seem to have served other purposes.

Palynology of ODP Leg 127 sites

This initial survey of pollen from 192 samples from Hole 794A, supplemented by 189 samples from Hole 795 and 797B, suggests that marine pollen assemblages from the southwestern Sea of Japan provide a consistent Neogene pollen stratigraphy and a solid basis for regional paleoenvironmental reconstructions. Late Miocene vegetation inferred from these pollen data, a mix of conifer and broad-leaf elements with now-extinct Tertiary types well represented, appears similar to Aniai-type floras of Japan. During the late Miocene through early Pliocene, as Tertiary types declined, conifers (including the Sequoia/Cryptomeria group) became more prominent than broad-leaf elements, and herbs played an increasing role in the vegetation. Middle Pliocene pollen assemblages imply significant changes in forest composition. In a 500,000-yr interval centered at ~4 m.y., Tertiary and warm-temperate deciduous types re-expanded and were comparable to or greater than middle-late Miocene levels. Temperate and cold-temperate conifers {Picea, Abies, Tsuga) were minimal. Subsequently, Tertiary and deciduous forest components (including Quercus) decreased, Picea, Tsuga, and Abies were again prominent, and herbs formed an increasingly larger part of the vegetation. Between ~3 m.y. and -2.5 m.y., conifers, except for Cryptomeria types, were prominent, Quercus continued to decline, and other broad-leaf trees were minor. Over the last 2 Ma, the very large and frequent changes in forest composition inferred from pollen in the Sea of Japan correspond to forest dynamics inferred from changes in pollen and floral assemblages throughout Japan. Given present vegetation/climate relationships, broad trends in Neogene climate inferred from these preliminary pollen data include decreasing temperatures, increasing seasonality in temperatures and precipitation, and increasing amplitude and frequency of climatic change. Two significant events, centered at ~9 m.y. and ~4 m.y., punctuate the gradual deterioration of the equable warm, humid subtropical/warm temperate late Miocene and early Pliocene climates. The first indication of cold-temperate conditions comparable to those of Pleistocene glacial intervals occurs ~3 m.y. Subsequently, regional climates oscillated rapidly between temperate and cold-temperate regimes that supported conifer and mixed broad-leaf forests; however, climatic extremes were apparently never great enough to displace warm-temperate and temperate forests from Honshu nor to produce arctic climates on the west coast of Japan.

Radiocarbon dates of peatland initiation across the northern high latitudes

A compilation of basal dates of peatland initiation across the northern high latitudes, associated metadata including location, age, raw and calibrated radiocarbon ages, and associated references. Includes previously published datasets from sources below as well as 365 new data points.

Radiocarbon ages and pollen record of a sediment core from Lake Lyadhej-To

An 1180-cm long core recovered from Lake Lyadhej-To (68°15'N, 65°45'E, 150 m a.s.l.) at the NW rim of the Polar Urals Mountains reflects the Holocene environmental history from ca. 11,000 cal. yr BP. Pollen assemblages from the diamicton (ca. 11,000-10,700 cal. yr BP) are dominated by Pre-Quaternary spores and redeposited Pinaceae pollen, pointing to a high terrestrial input. Turbid and nutrient-poor conditions existed in the lake ca. 10,700-10,550 cal. yr BP. The chironomid-inferred reconstructions suggest that mean July temperature increased rapidly from 10.0 to 11.8 °C during this period. Sparse, treeless vegetation dominated on the disturbed and denuded soils in the catchment area. A distinct dominance of planktonic diatoms ca. 10,500-8800 cal. yr BP points to the lowest lake-ice coverage, the longest growing season and the highest bioproductivity during the lake history. Birch forest with some shrub alder grew around the lake reflecting the warmest climate conditions during the Holocene. Mean July temperature was likely 11-13 °C and annual precipitation-400-500 mm. The period ca. 8800-5500 cal. yr BP is characterized by a gradual deterioration of environmental conditions in the lake and lake catchment. The pollen- and chironomid-inferred temperatures reflect a warm period (ca. 6500-6000 cal. BP) with a mean July temperature at least 1-2 °C higher than today. Birch forests disappeared from the lake vicinity after 6000 cal. yr BP. The vegetation in the Lyadhej-To region became similar to the modern one. Shrub (Betula nana, Salix) and herb tundra have dominated the lake catchment since ca. 5500 cal. yr BP. All proxies suggest rather harsh environmental conditions. Diatom assemblages reflect relatively short growing seasons and a longer persistence of lake-ice ca. 5500-2500 cal. yr BP. Pollen-based climate reconstructions suggest significant cooling between ca. 5500 and 3500 cal. yr BP with a mean July temperature 8-10 °C and annual precipitation-300-400 mm. The bioproductivity in the lake remained low after 2500 cal. yr BP, but biogeochemical proxies reflect a higher terrestrial influx. Changes in the diatom content may indicate warmer water temperatures and a reduced ice cover on the lake. However, chironomid-based reconstructions reflect a period with minimal temperatures during the lake history.

Pollen profile and age determination for sediment core M72/5_619-1 (22-GC3)

Sediments from the Black Sea, a region historically dominated by forests and steppe landscapes, are a valuable source of detailed information on the changes in regional terrestrial and aquatic environments at decadal to millennial scales. Here we present multi-proxy environmental records (pollen, dinoflagellate cysts, Ca, Ti and oxygen isotope data) from the uppermost 305 cm of the core 22-GC3 (42°13.53' N, 36°29.55' E) collected from a water depth of 838 m in the southern part of the Black Sea in 2007. The records span the last ~ 18 kyr (all ages are given in cal kyr BP). The pollen data reveal the dominance of the Artemisia-steppe in the region, suggesting rather dry/cold environments ~ 18-14.5 kyr BP. Warming/humidity increase during melt-water pulses (~ 16.1-14.5 kyr BP), indicated by d18O records from the 22-GC3 core sediment and from the Sofular Cave stalagmite, is expressed in more negative d13C values from the Sofular Cave, usually interpreted as the spreading of C3 plants. The records representing the interstadial complex (~ 14.5-12.9 kyr BP) show an increase in temperature and moisture, indicated by forest development, increased primary productivity and reduced surface run-off, whereas the switch from primary terrigenous to primary authigenic Ca origin occurs ~ 500 yr later. The Younger Dryas cooling is clearly demonstrated by more negative d13C values from the Sofular Cave and a reduction of pines. The early Holocene (11.7-8.5 kyr BP) interval reveals relatively dry conditions compared to the mostly moist and warm middle Holocene (8.5-5 kyr BP), which is characterized by the establishment of the species-rich warm mixed and temperate deciduous forests in the low elevation belt, temperate deciduous beech-hornbeam forests in the middle and cool conifer forest in upper mountain belt. The border between the early and middle Holocene in the vegetation records coincides with the opening of the Mediterranean corridor at ~ 8.3 kyr BP, as indicated by a marked change in the dinocyst assemblages and in the sediment lithology. Changes in the pollen assemblages indicate a reduction in forest cover after ~ 5 kyr BP, which was likely caused by increased anthropogenic pressure on the regional vegetation.

Pollen record and age determination of profile CS98-10 at Cape Shpindler, Yugorski Peninsula, northwest Russia

New pollen and radiocarbon data from an 8.6-m coastal section, Cape Shpindler (69°43' N; 62°48' E), Yugorski Peninsula, document the latest Pleistocene and Holocene environmental history of this low Arctic region. Twelve AMS 14C dates indicate that the deposits accumulated since about 13,000 until 2000 radiocarbon years BP. A thermokarst lake formed ca. 13,000-12,800 years BP, when scarce arctic tundra vegetation dominated the area. By 12,500 years BP, a shallow lake existed at the site, and Arctic tundra with Poaceae, Cyperaceae, Salix, Saxifraga, and Artemisia dominated nearby vegetation. Climate was colder than today. Betula nana became dominant during the Early Preboreal period about 9500 years BP, responding to a warm event, which was one of the warmest during the Holocene. Decline in B. nana and Salix after 9500 years BP reflects a brief event of Preboreal cooling. A subsequent increase in Betula and Alnus fruticosa pollen percentages reflects amelioration of environmental conditions at the end of Preboreal period (ca. 9300 years BP). A decline in arboreal taxa later, with a dramatic increase in herb taxa, reflects a short cold event at about 9200 years BP. The pollen data reflect a northward movement of tree birch, peaking at the middle Boreal period, around 8500 years BP. Open Betula forest existed on the Kara Sea coast of the Yugorski Peninsula during the Atlantic period (8000-4500 years BP), indicating that climate was significantly warmer than today. Deteriorating climate around the Atlantic-Subboreal boundary (ca. 4500 years BP) is recorded by a decline in Betula percentages. Sedimentation slowed at the site, and processes of denudation and/or soil formation started at the beginning of the Subatlantic period, when vegetation cover on Yugorski Peninsula shifted to near-modern assemblages.