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The rareness and inhomogeneity of the data points cause difficulties in the reconstruction of past average temperature. Optimal regional averaging is a method that can overcome these difficulties and obtain the average temperature of target area by means of optimal weights using limited temperature data. In this paper, the average temperature in the Northern Hemisphere is calculated by the optimal regional averaging method using two types of data: temperature data from Climatic Research Unit from 1901 to 2000 and maximum latewood density dataset of tree from 1500 to 1949. Five, ten, fifteen data points from CRU and forty data points from MXD are used in our research. The results show that even with the relatively less data used in this reconstruction, the method allows the reconstruction of the average temperature of the Northern Hemisphere more accurately, which provides the temperature information for palaeoclimate reconstruction. [ABSTRACT FROM AUTHOR]

Sediments of core YSJD-86GC (referred to as 86GC) collected from the southern South China Sea were selected for environmental magnetic studies. Combined with the published chronological framework, sediment magnetic properties were revealed for the study area since the MIS3 stage. The rock magnetic results indicate that low-coercivity magnetite is the main magnetic mineral within the sediments. Also, a certain amounts of hematite are present. The King plot and Day plot, which reflect the magnetic particle size, show that fine-grained pseudo-single-domain phase magnetic particles dominate the magnetic minerals in the sediments. Comparison of magnetic parameters and geochemical indicators show that magnetic properties of core 86GC sediments reflect a terrigenous input. Simultaneously, magnetic characteristics of the studied sediment are influenced by the quantity of terrigenous sediment input, oxidation-reduction conditions of the provenance area, and the transportation environment and distance. Sea level fluctuation caused by global climate change was the main factor for variation in concentration of magnetic minerals and magnetic particle size of the studied core sediments. Thus, variation of sediment magnetic properties in the study area can be used as an indirect indicator of sea level fluctuation. [ABSTRACT FROM AUTHOR]

Based on the nonlinear Lyapunov exponent and nonlinear error growth dynamics, the spatiotemporal distribution and decadal change of the monthly temperature predictability limit (MTPL) in China is quantitatively analyzed. Data used are daily temperature of 518 stations from 1960 to 2011 in China. The results are summarized as follows: (1) The spatial distribution of MTPL varies regionally. MTPL is higher in most areas of Northeast China, southwest Yunnan Province, and the eastern part of Northwest China. MTPL is lower in the middle and lower reaches of the Yangtze River and Huang-huai Basin. (2) The spatial distribution of MTPL varies distinctly with seasons. MTPL is higher in boreal summer than in boreal winter. (3) MTPL has had distinct decadal changes in China, with increase since the 1970s and decrease since 2000. Especially in the northeast part of the country, MTPL has significantly increased since 1986. Decadal change of MTPL in Northwest China, Northeast China and the Huang-huai Basin may have a close relationship with the persistence of temperature anomaly. Since the beginning of the 21st century, MTPL has decreased slowly in most of the country, except for the south. The research provides a scientific foundation to understand the mechanism of monthly temperature anomalies and an important reference for improvement of monthly temperature prediction. [ABSTRACT FROM AUTHOR]

Two consecutive magnetic flux ropes, separated by less than 30 s ( Δt < 30 s), are observed within one magnetic reconnection diffusion region without strong guide field in the Earth's magnetotail by Cluster multi-spacecraft. The flux ropes are characterized by bipolar signatures of the south-north magnetic field component B accompanied with strong core magnetic field B, intense current J and density depletions inside of them. In spite of the small but non-trivial global scale negative guide field (- B), there exists a directional change of the core fields of two flux ropes, i.e., − B for the first one, and + B for the second one. The directions of the core fields are the same as the ambient cross-tail magnetic field component ( B) just outside of flux ropes. Therefore, we suggest that the core field of flux ropes is formed by compression of the local preexisting B and that the directional change of core field is due to the change of local preexisting B. Such a change in ambient B might be caused by some microscale physics. [ABSTRACT FROM AUTHOR]

This study quantifies the surface denudation rate of granitic regolith via the application of the in situ cosmogenic Al and Be depth profile in China. The concentration ranges of Al and Be in the quartz along the ~3-m granitic regolith profile in Qinhuangdao are (4.9-23.1) × 10 and (2.3-36.6) × 10 atoms/g, respectively. With the exception of the surface sample, both Al and Be concentrations decrease exponentially with sample depth. The Chi-square best-fitting results revealed a total denudation rate of ~9 m/Ma averaged over a 10-10 a timescale, which is lower than the values observed in global granitic outcrops. Compared with global datasets, the flat terrain due to the lack of tectonic activities is most likely the dominant factor that controls the local denudation process. The surface sample offsets from the theoretical cosmogenic nuclide distribution implies that the denudation rate from river basin sediment could be overestimated because of the bioturbation in the surficial soil layer. [ABSTRACT FROM AUTHOR]

Fossil pollen records from 45 sites across China were evaluated and synthesized to document vegetation and climate change during Marine Isotope Stage 3 (MIS 3) at 60-27 ka and to understand the large-scale controls. During MIS3, vegetation type was dominantly forest in eastern China, forest steppe/meadow in the north and Tibetan Plateau, and steppe desert in northwestern arid China. We developed a semi-quantitative vegetation index to reflect change in plant abundance (by inferring the general climate conditions), with a vegetation score from 1 to 3 based on the different vegetation types inferred from pollen data at individual sites at intervals of 2,000 years. The reconstructed vegetation index shows higher values during MIS 3, especially during the period 53-40 ka, than at the Last Glacial Maximum. Our results also suggest that climate on the basis of vegetation change was cooler and drier during MIS 3 than during the Holocene optimum; however, MIS 3 vegetation was probably similar to modern vegetation. The close relationship between vegetation change, insolation and Asian summer monsoon strength suggests that climate variations, probably in both temperature and precipitation, are the primary drivers of regional vegetation change. Additional well-dated, high-resolution palaeoclimate records from many locations across China will be needed to understand the vegetation change and climate forcings on millennial and centennial scales within MIS 3. [ABSTRACT FROM AUTHOR]

A 310-cm-long sediment core, covering the last 10,200 years, was collected from Taro Co on the southwestern Tibetan Plateau and analyzed for pollen, grain size and total inorganic carbon content. The pollen data showed that vegetation changed from alpine steppe to alpine meadow during 10,200-8,900 cal a BP, to alpine steppe dominated by Artemisia during 8,900-7,400 cal a BP, to alpine meadow during 7,400-3,300 cal a BP and to alpine steppe after 3,300 cal a BP. Correspondingly, the pollen, grain size and total inorganic carbon content results revealed climatic change in this area over four stages. The initial stage was from 10,200 to 8,900 cal a BP, during which the climate changed from cold-dry to warm-humid. The second stage (8,900-7,400 cal a BP) was characterized by a warm and dry climate. However, at approximately 7,400 cal a BP, the climate began to become cold and humid, which continued until 3,300 cal a BP. The last stage, from 3,300 cal a BP to present, was characterized as cold and increasingly arid. Climatic events of the early and mid-late Holocene showed that the area was significantly affected by the westerlies. However, the mid-Holocene climate in Taro Co was controlled by the Indian monsoon. The mid-late Holocene depositional environment record of Taro Co was very important to further elaborate the degree of influence by the westerlies or Indian monsoon. [ABSTRACT FROM AUTHOR]

Changes in biodiversity during periods of global warming are of broad public concern. To study the effect of the warming process on the ecosystem, we carried out pollen analyses on samples from seven selected sections at Qingyang, Ningxian, Yangling, Binxian, Baoji, Yanshi, and Lingbao on the Chinese Loess Plateau in order systematically to evaluate changes in plant diversity since the Last Glacial Maximum (LGM). The plant richness indices (Simpson's diversity index and rarefaction analysis) indicated that the plant diversity of each section increased during the process of warming from the LGM to the Holocene Optimum, especially at Baoji and Lingbao. These results are consistent with many long-timescale geological records, which show that warming can increase biodiversity; therefore, the popular viewpoint that warming leads to biodiversity loss or species extinction needs to be re-examined. [ABSTRACT FROM AUTHOR]

Extensive lacustrine deposits in the eastern Tarim Basin provide records of climate change influenced by the westerly winds and the Asian monsoon. To characterize the evolution of climate change in this region, we analyze elemental concentrations of barium (Ba) from the Ls2 drill core of Lop Nor, a paleo-lakebed located in the eastern Tarim Basin. Biogenic Ba concentrations from this drill core display a large-amplitude oscillation that generally follows a pattern similar to that of Artemisia content and ostracod assemblages, suggesting that is may serve as an index for climate change experienced in the basin. Our results indicate that biogenic Ba is especially sensitive to precipitation. All climatic proxies served in this study vary significantly over late Miocene to early Pleistocene time period. Strong aridification of eastern Tarim in the late Miocene to the early Pliocene may be attributed to a latitudinal shift in the westerly winds, which would have resulted in more moisture transported to southern and eastern Tibet. The growth of the Himalaya and Tibetan Plateau may have acted as an orographic barrier that blocked moisture sourced in the south from the northern margins of the plateau. We link weaker aridification in the late Pliocene to an increased intensity of the Indian Monsoon. [ABSTRACT FROM AUTHOR]

1-Chloro-1,1-difluoroethane (HCFC-142b) was both ozone depleting substance under restriction of the Montreal Protocol on Substances that Deplete the Ozone Layer ( Montreal Protocol) and potent greenhouse gas with high GWP. Controlling its emissions in China will contribute to both mitigating climate change and protecting ozone. A national emission inventory of HCFC-142b for China during 2000-2012 was established and projected to 2050 based on the 2006 IPCC Guidelines for National Greenhouse Gas Inventories and the Montreal Protocol, showing that (i) in contrast to the downward trend revealed by existing researches, HCFC-142b emissions kept increasing from 0.1 kt/y in 2000 to the peak of 14.4 kt/y in 2012, making China a crucial contributor to global HCFC-142b emissions and (ii) for future emission projections, a continuous increase from 14.9 kt/y in 2013 to 97.2 kt/y in 2050 was anticipated under the business-as-usual (BAU) scenarios, while a reduction of about 90% of the projected BAU emissions would be obtained by fulfilling the Montreal Protocol, namely an accumulative mitigation of 1578 kt HCFC-142b from 2013 to 2050, equal to 103 kt ODP and 3504 Tg CO emissions. Emissions from each province in 2012 were also estimated to identify key emission areas. Among the 31 mainland provinces in China (Hong Kong, Macao, and Taiwan were not included), Jiangsu, Zhejiang, Shandong, and Guangdong had the highest emission rates in 2012 (2.06, 1.85, 1.52, and 1.04 kt/y, respectively); Zhejiang, Jiangsu, and Shanghai exhibit the strongest emission strength (0.83, 0.59, and 0.54 t/km, respectively), much higher than the average national level of 0.33 t/km. [ABSTRACT FROM AUTHOR]