Interests on climate change in the source region of Yangtze River have been raised since it is a regionwith the greatest warming over the Tibetan Plateau (TP). A 70-year history of precipitation δ 18 O has been recovered using an ice core record retrieved in a plat portion of the firn area in the Guoqu Glacier (33°34′37.8″N, 91°10′35.3″E, 5720 m a.s.l.), Mt. Geladaindong (the source region of Yangtze River), in November, 2005. By using a significant positive relationship between ice core δ 18 O record and summer air temperature (July to September) from the nearby meteorological stations, a history of summer air temperature has been reconstructed for the last 70 years. Summer temperature was relatively low in 1940s and high in 1950s to the middle of 1960s. The lowest temperature occurred in the middle of 1970s. Temperature was low in 1980s and dramatically increased since 1990s, keeping the trend to the beginning of the 21st century. The warming rate recorded in the ice core with 0.5℃/10 a since 1970s is much higher that that in the central TP and the Northern Hemisphere (NH), and it becomes 1.1℃/10 a since 1990s which is also higher than these from the central TP and the NH, reflecting an accelerated warming and a more sensitive response to global warming in the high elevation region.ice core δ 18 O records, summer temperature variations, source region of Yangtze River, Tibetan Plateau Global warming in the 20th century has been universally recognized, especially for the last decade of the century, which was considered as the most warming decade during the recent 1000 years [1] , with no exception for Tibetan Plateau (TP) [2][3][4] . TP, treated as a sensitive areas for climate change [5][6][7][8][9][10] , has been a "hot spot" in research of global change all through. Results of meteorological instrumental data from stations showed that the source region of Yangtze River located in the center of the TP is the most sensitive area to global warming, and also presents the most intensive warming trend [11,12] . Due to the frangible and sensitive environment in the source region of Yangtze River, and violent response to the climate change, such as glacier retreat, permafrost degradation, wetland dryness, and lake shrinking [11] , further expanding the knowledge of the characteristics of climate change in this region can establish a base for research work related to environment variations in the region, which not only are helpful to farming/pasturing and ecology repairing in the area, but also provide opportunities to contribute to the economic and social developments in the downstream regions of Yangtze River.Due to the sparse meteorological stations in the source region of Yangtze River, combined with the relatively short history of observed data (approximately GEOGRAPHY

Abstract. Two ice cores were retrieved from high elevations ( ∼ 5800 m a.s.l.) at Mt. Nyainqêntanglha and Mt. Geladaindong in the southern and central Tibetan Plateau region. The combined tracer analysis of tritium ( 3 H), 210 Pb and mercury, along with other chemical records, provided multiple lines of evidence supporting that the two coring sites had not received net ice accumulation since at least the 1950s and 1980s, respectively. These results implied an annual ice loss rate of more than several hundred millimeter water equivalent over the past 30-60 years. Both mass balance modeling at the sites and in situ data from the nearby glaciers confirmed a continuously negative mass balance (or mass loss) in the region due to dramatic warming in recent decades. Along with a recent report on Naimona'nyi Glacier in the Himalayas, the findings suggest that the loss of accumulation area of glacier is a possibility from the southern to central Tibetan Plateau at high elevations, probably up to about 5800 m a.s.l. This mass loss raises concerns over the rapid rate of glacier ice loss and associated changes in surface glacier runoff, water availability, and sea levels.

Understanding past atmospheric dust variability is necessary to put modern atmospheric dust into historical context and assess the impacts of dust on the climate. In Asia, meteorological data of atmospheric dust is temporally limited, beginning only in the 1950s. High‐resolution ice cores provide the ideal archive for reconstructing preinstrumental atmospheric dust concentrations. Using a ~500 year (1477–1982 A.D.) annually resolved calcium (Ca) dust proxy from a Tibetan Plateau (TP) ice core, we demonstrate the lowest atmospheric dust concentrations in the past ~500 years during the latter twentieth century. Declines in late nineteenth to twentieth century Ca concentrations significantly correspond with regional zonal wind trends from two reanalysis models, suggesting that the Ca record provides a proxy for the westerlies. Twentieth century warming and attendant atmospheric pressure reductions over northern Asia have potentially reduced temperature/pressure gradients resulting in lower zonal wind velocities and associated dust entrainment/transport in the past ~500 years over the TP.

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ABSTRACT. A multiple parameter dating technique was used to establish a depth/age scale for a 171.3 m (145.87 m w.e.) surface to bedrock ice core (Bl2003) recovered from the cold recrystallization accumulation zone of the Western Belukha Plateau (4115 m a.s.l.) in the Siberian Altai Mountains. The ice-core record presented visible layering of annual accumulation and of δ Sulfate peaks coincident with volcanic eruptions, the Tunguska meteorite event, and the 1842 dust storm were used to verify dating. Analysis of the Bl2003 ice core reveals that the modern Altai glaciers were formed during the Younger Dryas (YD) (∼10 950 to ∼7500 cal a BC), and that they survived the Holocene Climate Optimum (HCO) (∼6500 to ∼3600 cal a BC) and the Medieval Warm Period (MWP) (∼640 to ∼1100 AD). A decrease in air temperature at the beginning and an abrupt increase at the end of the YD were identified. Intensification of winds and dust loading related to Asian desert expansion also characterized the YD. During the YD major ion concentrations increased significantly, up to 50 times for Na + (background), up to 45 times for Ca 2+ and Mg 2+ , and up to 20 times for SO 4 2− relative to the recent warm period from 1993 to 2003. A warm period lasted for about three centuries following the YD signaling onset of the HCO. A significant and prolonged decrease in air temperature from ∼2000 to ∼600 cal a BC was associated with a severe centennial drought (SCD). A sharp increase in air temperatures after the SCD was coincident with the MWP. After the MWP a cooling was followed gradually with further onset of the Little Ice Age. During the modern warm period an increase in air temperature is noted, which nearly reaches the average of HCO and MWP air temperature values.