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Climatic reconstruction from peat deposits is an important aspect of Quaternary research. Previous studies of the peatlands in the Mu Us Desert in northern China have focused on the processes of paleoclimatic evolution, but the history of peatland development remains unclear due to the absence of comparative studies. Here we present a synthesis of the available records documenting peatland development within the Mu Us Desert since the last deglaciation. We combine paleoclimatic records from profiles from two new sites with previously published results from 12 sites. Our aim is to reconstruct the temporal and spatial record of peatland development and to determine its driving forces. The results show that the peatlands developed in two phases: from ~15 ka until the early Holocene and from 6.5–3 ka when there was a significant expansion of their spatial extent. These phases correspond to two distinct types of paludification process, and both were closely related to changes in the East Asian monsoon. A final stage after 2 ka resulted from the significant weakening of the monsoon, during which peat accumulation ceased.

An excavated profile of aeolian-palaeosol-lacustrine sediments (the Wapianliang profile), located at the southeastern part of the Mu Us Desert, Northern China, was studied to reconstruct regional Holocene environmental changes. A chronology was established based on three AMS 14C and two OSL dates, and variations in the lithology and grain size, magnetic susceptibility, soil micromorphology, and chemical elements were used to explore the regional depositional environments during the Holocene. The results showed that since around 14 ka BP, this region had experienced seven alternations of wetting and drying. A shallow lake, which was identified by celadon lacustrine sediments with sporadic freshwater gastropod fossils, occurred in this area from around 13.0 ka BP to 9.9 ka BP. There existed two obvious intervals of soil formation, inferred from the environmental proxies of the palaeosol/sandy palaeosol layers, with relatively fine average grain-size, high magnetic susceptibility value, remarkable pedogenesis features, and strong chemical weathering, in particular, a well-developed palaeosol layer dating from the middle Holocene (8.6 ka BP to 4.2 ka BP). A weakly-developed palaeosol layer (from around 1.2 ka BP) at the upper part of the profile is possibly an indication of the Medieval Warm Period. This implies a forest steppe environment at both of these sedimentary stages. After 0.9 ka BP, a desert environment returned, analogous to before around 13.0 ± 1.4 ka BP, between 9.9 ± 1.1 ka BP to 8.6 ka BP, and between 4.2 ka BP to 1.6 ka BP, indicating the aggravation of aeolian activity and the expansion of mobile sand dunes. The variations in sedimentary environments were mainly triggered by changes in the East Asian Summer Monsoon (EASM).

Abstract. The reconstructed surface-temperature time series from boreholes in Antarctica have significantly contributed to our understanding of multidecadal and centennial temperature changes and thus provide a good way to evaluate the ability of climate models to reproduce low-frequency climate variability. However, up to now, there has not been any systematic model–data comparison based on temperature from boreholes at a regional or local scale in Antarctica. Here, we discuss two different ways to perform such a comparison using borehole measurements and the corresponding reconstructions of surface temperature at the West Antarctic Ice Sheet (WAIS) Divide, Larissa, Mill Island, and Styx Glacier in Antarctica. The standard approach is to compare the surface temperature simulated by the climate model at the grid cell closest to each site with the reconstructions in the time domain derived from the borehole temperature observations. Although some characteristics of the reconstructions, for instance the nonuniform smoothing, limit to some extent the model–data comparison, several robust features can be evaluated. In addition, a more direct model–data comparison based on the temperature measured in the boreholes is conducted using a forward model that simulates explicitly the subsurface temperature profiles when driven with climate model outputs. This comparison in the depth domain is not only generally consistent with observations made in the time domain but also provides information that cannot easily be inferred from the comparison in the time domain. The major results from these comparisons are used to derive metrics that can be applied for future model–data comparison. We also describe the spatial representativity of the sites chosen for the metrics. The long-term cooling trend in West Antarctica from 1000 to 1600 CE (−1.0 ∘C) is generally reproduced by the models but often with a weaker amplitude. The 19th century cooling in the Antarctic Peninsula (−0.94 ∘C) is not reproduced by any of the models, which tend to show warming instead. The trend over the last 50 years is generally well reproduced in West Antarctica and at Larissa (Antarctic Peninsula) but overestimated at other sites. The wide range of simulated trends indicates the importance of internal variability in the observed trends and shows the value of model–data comparison to investigate the response to forcings.

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