High-resolution planktic stable isotope and trace element record of ODP Hole 161-976

Multi-decadal to centennial planktic d18O and Mg/Ca records were generated at ODP976 in the Alboran Sea. The site is in the flow path of Atlantic inflow waters entering the Mediterranean and captured North Atlantic signals through the surface inflow and the atmosphere. The records reveal similar climatic oscillations during the last two glacial-to-interglacial transitions, albeit with a different temporal pacing. Glacial termination 1 (T1) was marked by Heinrich event 1 (H1), post-H1 Bolling/Allerod (B/A) warming and Younger Dryas (YD) cooling. During T2 the H11 d18O anomaly was twice as high and lasted 30% longer than during H1. The post-H11 warming marked the start of MIS5e while the subsequent YD-style cooling occurred during early MIS5e. The post-H11 temperature increase at ODP976 matched the sudden Asian Monsoon Termination II at 129 ka BP. Extending the 230Th-dated speleothem timescale to ODP976 suggests glacial conditions in the Northeast Atlantic region were terminated abruptly and interglacial warmth was reached in less than a millennium. The early-MIS5e cooling and freshening at ODP976 coincided with similar changes at North Atlantic sites suggesting this was a basin-wide event. By analogy with T1 we argue that this was a YD-type event that was shifted into the early stages of the last interglacial period. This scenario is consistent with evidence from northern North Atlantic and Nordic Sea sites that the continuing disintegration of the large Saalian Stage (MIS6) ice sheet in Eurasia delayed the advection of warm North Atlantic waters and full-strength convective overturn until later stages of MIS5e.

Neogene palaeoclimate reconstructions in Anatolia (Turkey)

Neogene basins are widespread in Turkey and contain important lignite deposits. In this study, we reconstruct quantitatively the Late Oligocene-Miocene climate evolution in western and central Anatolia by applying the Coexistence Approach to the palynoflora. The obtained results are compared with the data derived from the published and ongoing studies in western and central Anatolia palynofloras by application of the Coexistence Approach. The Coexistence Approach results show that the sedimentation mainly developed on terrestrial environment under the warm subtropical climatic conditions and marine influence during the Chattian and Aquitanian period in western Anatolia (16.5-21.3°C of mean annual temperature (MAT) and 5.5-13.3°C of mean temperature of coldest month (CMT)). After the regression of the sea during the Burdigalian period, the vegetation developed under the terrestrial conditions, which had started in the Burdigalian time in western and central Anatolia and continued in the early-middle Serravallian period. Warm subtropical climate is suggested during the Chattian and Aquitanian period in western Anatolia and becomes cooler in subtropical conditions because of decreasing of the P/A-ratio during the latest Burdigalian-Langhian. The climate was subtropical in western and central Anatolia during the Early-Late Serravalian due to the increasing of the subtropical elements (17.2 to 20.8°C of MAT and 9.6 to13.1°C of CMT). Besides, decreasing of the CMT and MAT values in western and central Anatolia supports the latest Chattian-earliest Aquitanian warming and middle Miocene climatic optimum that is also globally observed. Warm temperate climatic conditions are observed in the Late Miocene. During the early-middle Tortonian, the values are 15.6 to 20.8°C for the MAT, 5.5 to 13.3°C for the CMT and 823 and 1520 mm for the mean annual precipitation (MAP). They had also dry seasons due to lower boundary of MAP lying at 823mm during the middle-Late Tortonian. The palaeotopography of central Anatolia was higher when compared to that of western Anatolia because dominance of the mountain forests was present during the Middle-Late Miocene in central Anatolia. This study provides the first quantitative model for Late Oligocene-Miocene palaeoclimatic evolution in western and central Anatolia.

A fractional vegetation cover remote sensing product on pan-arctic scale with link to geotiff image

The paper presents first results of a pan-boreal scale land cover harmonization and classification. A methodology is presented that combines global and regional vegetation datasets to extract percentage cover information for different vegetation physiognomy and barren for the pan-arctic region within the ESA Data User Element Permafrost. Based on the legend description of each land cover product the datasets are harmonized into four LCCS (Land Cover Classification System) classifiers which are linked to the MODIS Vegetation Continuous Field (VCF) product. Harmonized land cover and Vegetation Continuous Fields products are combined to derive a best estimate of percentage cover information for trees, shrubs, herbaceous and barren areas for Russia. Future work will concentrate on the expansion of the developed methodology to the pan-arctic scale. Since the vegetation builds an isolation layer, which protects the permafrost from heat and cold temperatures, a degradation of this layer due to fire strongly influences the frozen conditions in the soil. Fire is an important disturbance factor which affects vast processes and dynamics in ecosystems (e.g. biomass, biodiversity, hydrology, etc.). Especially in North Eurasia the fire occupancy has dramatically increased in the last 50 years and has doubled in the 1990s with respect to the last five decades. A comparison of global and regional fire products has shown discrepancies between the amounts of burn scars detected by different algorithms and satellite data.

Arctic aboveground tundra biomass dynamics between 1982 and 2010

Numerous studies have evaluated the dynamics of Arctic tundra vegetation throughout the past few decades, using remotely sensed proxies of vegetation, such as the normalized difference vegetation index (NDVI). While extremely useful, these coarse-scale satellite-derived measurements give us minimal information with regard to how these changes are being expressed on the ground, in terms of tundra structure and function. In this analysis, we used a strong regression model between NDVI and aboveground tundra phytomass, developed from extensive field-harvested measurements of vegetation biomass, to estimate the biomass dynamics of the circumpolar Arctic tundra over the period of continuous satellite records (1982-2010). We found that the southernmost tundra subzones (C-E) dominate the increases in biomass, ranging from 20 to 26%, although there was a high degree of heterogeneity across regions, floristic provinces, and vegetation types. The estimated increase in carbon of the aboveground live vegetation of 0.40 Pg C over the past three decades is substantial, although quite small relative to anthropogenic C emissions. However, a 19.8% average increase in aboveground biomass has major implications for nearly all aspects of tundra ecosystems including hydrology, active layer depths, permafrost regimes, wildlife and human use of Arctic landscapes. While spatially extensive on-the-ground measurements of tundra biomass were conducted in the development of this analysis, validation is still impossible without more repeated, long-term monitoring of Arctic tundra biomass in the field.

Table 2. Percentage of palynomorphs found in each sample through Longling section

The Longling Coal Mine (W. Yunnan) is situated in an area of substantial geotectonic activity. Its Late Pliocene palynoflora is of considerable interest, since the area represents a centre of biodiversity. Eighty-two palynomorphs belonging to 61 families were recovered from the lignite. The palynoflora is dominated by angiosperms (68.3%), with ferns (24.4%), gymnosperms (4.9%) and algae (2.4%). Comparisons indicate that most of the palynoflora was derived from the Montane Humid Evergreen Broad-leaved Forest, with lesser contributions from the Tsuga dumosa Forest and Evergreen Coniferous Broad-leaved Mixed Forest, as well as the Montane Mossy Evergreen Broad-leaved Forest. This indicates that the Late Pliocene climate was cooler than that of the present. In the course of the accumulation of the lignite, the climate underwent five major phases of warming and cooling.