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This paper reviews recently published literature, most of which was published in Chinese, and searches for regional patterns of Holocene changes useful in depicting global patterns. The Holocene in the Xinjiang region can be divided into three stages: a warming and dry early stage (from 11 ∼ 10 to 8 ∼ 7 ka BP), a warm and wet middle stage (from 8 ∼ 7 to 4.5 ∼ 3 ka BP) and a fluctuating cool and dry late stage (since 4.5 ∼ 3 ka BP). The Holocene in the northern Tibetan Plateau can also be divided into three stages: a warming and wet stage (from 10.5 ∼ 10 to 5 ∼ 4 ka BP), followed by a variable drying and probably warm stage (5 ∼ 4 to 3 ka BP) and ending with a cool and dry stage (since 3 ka BP). In the Inner Mongolian Plateau, the early Holocene (from 10.5 ∼ 9.5 to 8 ∼ 7.5 ka BP) was warming and dry, and a warm and wet climate occurred from 7.5 to 3.5, during which the best time was 6.3–3.8 ka BP; the climate has been variably drying and probably cooling since 3.5 ka BP. In the northwestern part of the Loess Plateau, several Holocene palaeosols have been identified (10–9, 7.5–5, 4–3 and 2.7–2 ka BP) with the 7.5–5 ka BP palaeosol being most strongly expressed. The best-developed palaeosol-equivalent in major valleys is a swamp-wetland facies deposited between 8885 and 3805 14C yr BP under an extremely wet regime. The climate has fluctuated significantly at least three times around a dry and probably cool regime after the swamp-wetland facies-depositional period. Our summary shows that the Holocene Climatic Optimum occurred nearly contemporaneously (8–5 ka BP) at all sites in the Xinjiang region, in the Inner Mongolian Plateau and in the northwestern part of the Loess Plateau. A warming and wet early Holocene (10–8 ka BP) in the northern Tibetan Plateau is most likely related to high effective soil moisture resulting from snow and ice melting. We propose here that the middle Holocene Climatic Optimum (8–5 ka BP) in arid to semi-arid China was primarily a delayed response of the low latitude oceans to high latitude peak insolation (9–8 ka BP). [ABSTRACT FROM AUTHOR]

The focus of this paper is on the reconstruction of the mid-Holocene climatic changes based on the pollen records contained in a 6.2 m thick section in the southern part of the Tengger Desert, northwestern China. To understand the modern analogues of the mid-Holocene changes, modern pollen spectra across different vegetation zones from the Qilian Mountains to the lowland Tengger Desert were studied first. Four pollen combinations were identified, corresponding to four different modern ecological environments: (1) a Picea-Artemisia combination in a spruce forest and its vicinity; (2) an Artemisia-Chenopodiaceae-Gramineae-Salix combination in a mixture belt of montane grassland and poplar woodland; (3) a Chenopodiaceae-Artemisia-Nitraria combination in a desert steppe belt; and (4) an Elaeagnus-Artemisia-Chenopodiaceae-Nitraria combination in a desert riparian forest. Our study also shows that a relatively low percentage of Picea pollen (30–10%) seems to be associated with water transportation (alluvial deposits) and a very low percentage of Picea pollen (10–5%) appears to be related to long-distance air transportation. With references to the modern relationships between pollen assemblages and associated bioclimates, the pollen sequence covering the period between 8500 and 3000 cal. BP was used to infer the climatic change history. The results show that a warmer and drier climate dominated between 8500 and 7950 cal. BP. Subsequent decreases in Artemisia and warm desert forbs/shrubs taxa and contemporaneous fluctuating increases in montane coniferous and aquatics elements from 7950 to 7400 cal. BP reflect a fluctuating increase in humidity and/or a fluctuating decrease in temperature. The following period from 7400 to 5650 cal. BP was generally warm with the Holocene Climate Optimum occurring between 7400 and 6500 cal. BP. A remarkably cool spell followed between 6500 and 6300 cal. BP that was then succeeded by a warmer and more humid period between 6300 and 5650 cal. BP. The period between 5650 and 4450 cal. BP was characterized by drastic oscillations in climatic conditions with three humid and probably cold spells intervened by three relatively dry and warm spells. The period between 4450 and 3500 cal. BP was cold and humid, followed by a wet spell as indicated by a very high percentage of Typha pollen. [ABSTRACT FROM AUTHOR]

Wetlands cover large areas in the Democratic Republic of the Congo. However, their extent and distribution have not been accurately mapped. While wetland forests remain largely undisturbed, increasing threats by anthropogenic activities have been observed in areas with high population density per arable or exploitable land. The scarcity of terra firma forests in some territories of the Democratic Republic of the Congo has forced local communities to develop cropping methods that allow for cultivation in periodically flooded areas. Assessing wetlands extent and status is critical for long term conservation of these highly vulnerable ecosystems. In this study, we use multi-source and multi-resolution optical and radar remotely sensed data and elevation derived indices to map the wetlands of the Democratic Republic of the Congo. Results showed that wetlands are a significant part of the landscape in the country, covering an estimated 440,000 km or 19.2 % of the total country area. By combining the wetlands map with a previously produced land cover depiction of the Democratic Republic of the Congo, a map including forested wetlands as a thematic class was derived. We investigated whether high terra firma population density and low percent remaining terra firma forest are related at the lowest administrative level (Sector); specifically, we tested these two variables as predictors of wetland forest cover loss. A polynomial regression relating population and primary terra firma forest to wetland forest cover loss yielded an r of 0.76, illustrating a nascent and significant land cover change dynamic. Areas most at risk for future wetland forest loss lie in the western Cuvette, and include (north-south) the Sud-Ubangi, Mongala, Equateur and Mai-Ndombe Districts. By quantifying available upland forest resources and overlaying with population density, it was possible to identify stressed areas inside of the forest domain (traditionally known for having generically high levels of forest resources). Results illustrate the need for addressing issues of wetland forest management and protection in the Democratic Republic of the Congo, especially where increasing populations are exhausting primary terra firma forest resources. [ABSTRACT FROM AUTHOR]

We present the first study from the Bransfield Basin that extends through the Holocene, recording the variable climate history back to the decoupling of the ice sheet from the continental shelf ∼10 650 calendar years before present (cal yr BP). Detailed sediment analysis reveals three stratigraphic units in PC-61 concomitant with three sedimentary environments, similar to sedimentary facies reported elsewhere: 1) subglacial, 2) glacial proximal/sub-ice shelf, and 3) open marine. These interpretations are based on a variety of sedimentological criteria, supported by ten AMS radiocarbon dates and detailed diatom analysis. We note two significant volcanic ash layers (tephra) at 3870 and 5500 cal yr BP from nearby Deception Island. Based on diatom assemblage analysis, we identify five separate climate regimes, highlighting a significantly shorter Mid-Holocene Climatic Optimum than reported by other studies (6800-5900 cal yr BP). This period is marked by the highest Eucampia antarctica var. antarctica and Fragilariopsis curta abundance, total diatom abundance, sediment accumulation rates, and low magnetic susceptibility. We also identify a less pronounced Neoglacial period relative to other studies, which includes an increase of Cocconeis/Rhizosolenia spp. assemblage related to unstable surface water conditions. Such observations probably reflect important regional variations in atmospheric or ocean circulation patterns. [ABSTRACT FROM AUTHOR]

Measurements of the two water stable isotopes (δD and δ[sup 18]O) along EPICA (European Project for Ice Coring in Antarctica) Dome C ice core are combined with simple isotopic modelling (distillation models) to reconstruct the variability of both the site temperature (East Antarctica) and the moisture source temperature (nowadays probably the subantarctic Indian Ocean). We discuss the difference between the reconstructed site and source temperature profiles with respect to the initial isotopic data. We show that (i) the early-Holocene optimum appears first in Antarctica and 800 years later in the Southern Ocean, and (ii) during the last 5000 years, the site and source temperatures co-vary at the centennial timescale. An 833-year periodicity is observed only on deuterium and site temperature and therefore probably of local origin. [ABSTRACT FROM AUTHOR]

Lacustrine sediments from Lake Isdalsvatn downstream from the southwestern margin of the plateau glacier Hardangerjøkulen, central-southern Norway, show that the lake received glacial meltwater until 7890 ± 95 BP. A thin, bluish-grey minerogenic silt layer probably reflects a short glacial (re)advance between 7005 ± 90 and 6835 ± 150BP. After the latter date, inflow of glacial meltwater ceased, indicating that small or, more probably, no glaciers existed on the southwestern Hard angerjøkulen plateau. A drop in organic content and a slight increase in detrital content inferred from magnetic susceptibility at 120cm depth in the core, may indicate some glacier activity in the catchment from about 3400 BP. Textural changes at 50cm depth indicate increased Neoglacial activity in the upper catchment area from 2265 ± 80 BP. Differences in glacier chronologies between the southern and northern sectors of Hardangerjøkulen may be explained partly by different glacier responses to the precipitation and wind distribution at opposite sides of the ice cap. [ABSTRACT FROM PUBLISHER]