Geoscience

Updated Understanding on Climate Changes in Asia

An independent home-grown research result, accomplished by Prof. An Zhisheng from the State Key Laboratory of Loess and Quaternary Geology, the Institute of Earth Environment, CAS in joint efforts with his domestic and international colleagues, was published in Scientific Reports on Aug. 31, 2012, entitled “Interplay between the Westerlies and Asian monsoon recorded in Lake Qinghai sediments since 32 ka”. This study carried out the multi-proxies analyses on the drilling core samples from Lake Qinghai retrieved by ICDP and the Chinese Scientific Drilling Project, and reconstructed the continuous and highest-resolution evolution history of both the Westerlies and the ASM since 32 ka on the northeastern Tibetan Plateau. These records document the anti-phase relationship of the Westerlies and the Asian Summer Monsoon (ASM) on both glacial-interglacial and glacial millennial timescales, and the weakening of ASM circulation and the abrupt intensification of the Westerlies on millennial timescales during the Holocene, demonstrating their linkages to high latitude ice sheet, North Atlantic and low latitude climate, and the possible influence of changes in solar activity on ASM changes and the Westerlies climate on millennial timescales. These results are critical for us to understand the interplay history of the Westerlies climate and the ASM, which will provide key observational constraints for understanding the climate changes in humid/arid transition zone in Asia and improving models and their prediction of ASM and Westerlies changes under the scenario of global warming in the future.

Plausible Impact of Climate Change on Runoff

The arid region of Northwest China is characterized by a waving geomorphic land surface with inter-spacing mountains and depressed basins. Therefore, the typical landscape comprised vertically with mountain - oasis - desert ecosystems. Water, mostly formed at the high mountain areas, is a critical factor to drive the energy and mass circulation in this region, and exhibited sensitive response to global climate change. A research team led by Prof. Chen Yaning at the Xinjiang Institute of Ecology and Geography, CAS, recently revealed that the warming in this hyper-arid region was spatially and temporally uneven. The increasing rate of temperature in the mountain areas was detected as the fastest; compared with period before 1990s, the temperature after 1990s increased 57.7% at the mountain regions. While the relative temperature rising in oasis and desert areas were 10.6% and10.4% respectively. The precipitation exhibited a general upward tendency. However, precipitation in desert areas showed inconspicuous change. This spatially uneven change of climate causes puts important impacts on the vulnerable ecosystems in the arid region of Northwest China. In addition, the group has constructed and developed a hydrological sensitive analysis method, by which they quantified the effects of climate change and human activities on runoff change are 90.5% and 9.5%, respectively. This method has the advantage of better applicability with physical basis compared with the multiple regression method, and simpler than hydrological model. This team also reported some results on extremes in the arid region. They found that temperature extremes show a warming trend with a large proportion of stations having statistically significant trends for all temperature indices. The regional occurrence of extreme cold days, e.g. frost days, ice days, has significant decreased, and the occurrence of extreme hot days, e.g. hot days and hot nights, has significantly increased. The above achievements have been recently published on journal Theoretical and Applied Climatology.