Dry/wet patterns in dryland areas show significant differences in the decades prior to and after 1980, specifically, the change in aridity was opposite in American and African drylands between 1948-1979 and 1980-2008, which was closely related to multi-decadal changes in surface sea temperature.

Previous research indicate conflicting ideas on how dryland areas respond to climate change. Some point out that under the background of global warming, the area with more precipitation will have more precipitation, and the area with drought will become more arid. However, some research concluded that 9.5% of global land area showed dry getting wetter and wet getting drier.

Based on the above results, Chen Yaning, a researcher from Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, used the Precipitation/Potential evaporation (P/PET) index to analyze changes occurring in the dry/wet structure of various spatial and temporal scales during 1948–2008.

The results show that the emergence of complex aridity changes on a regional scale. While aridity generally decreased in the drylands of Asia during 1948–2008, the change in aridity was opposite in the drylands of the American and African continents between 1948 and 1979 and 1980–2008. Specifically, drylands in the American continent showed a wetting tendency during 1948–1979 and a drying tendency during 1980–2008, whereas drylands in the African continent underwent significant drying during 1948–1979 followed by subtle wetting in 1980–2008.

"Even though rapid warming since the 1980s has become an increasingly important cause of the recent global drying trend, especially in East and Central Asia, the changes in aridity in the American and African drylands is attributable to natural variabilities in precipitation associated with multi-decadal surface sea temperature changes, along with large-scale circulation patterns," said Chen Yaning.

Results of the study were published on Global and Planetary Change, entitled" Dry/wet pattern changes in global dryland areas over the past six decades".

Contact: LIU Jie, Xinjiang Institute of Ecology and Geography

E-mail: liujie@ms.xjb.ac.cn