China - Records show large scale climate change

The unsaturated zone records shows, compared with the ice core records, that a large-scale climate difference took place between mountain regions and the desert during the 20th century.

Title of paper: Chloride as a tracer and climatic change during the last 2000 years recorded from unsaturated zone of Badain Jaran desert

Authors: J. Z. Ma (1) and W. M. Edmunds (2)
(1) Center for Arid Environment and Palaeoclimate Research, Key Laboratory of Western China’s Environmental System, Lanzhou University, Lanzhou 730000, China
(2) Oxford Centre for Water Research, Oxford University, Oxford, OX1 3TB, UK

The history of groundwater recharge and climatic change during the last 2000 years has been estimated and reconstructed using environmental chloride from unsaturated zone profiles in the southeast Badain Jaran desert, NW China.

The long-term recharge was estimated to be 0.96-1.36 mm yr-1 from three boreholes with depth of 7.4-22.5 m based on the chloride mass balance approach, which showed that no effective modern recharge is taking place, but that the lakes are supported by regional groundwater flow, the age of the water being late Pleistocene as inferred from the isotopic compositions.

The unsaturated profiles well preserved the climatic change events of 10-20 years duration and the climate can be subdivided into 3 wet periods and several dry periods. Before 1300 AD it was relatively dry but distinct wet periods may be recognised between 1340-1450, 1500-1610 and 1710-1820 AD.

At ca. 1500-1550 AD, which is an important datum, the climate witnessed a violent change from drought to wet. The considerable decrease in recharge rate indicated that it was an important turning event of the local climate from wet to dry at the beginning of 1800s, and then the climate deteriorated severely during the last 200 yrs.

The unsaturated zone records shows, compared with the ice core records, that a large-scale climate difference took place between mountain regions and the desert during the 20th century.

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© International Center for Agricultural Research in the Dry Areas (ICARDA), 2006

Published: 13 May 2006

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