As the birthplace of many major Asian rivers, the Tibetan Plateau plays a significant role in the continent’s energy and water cycles via evapotranspiration. A recent study by TPE scientists reveals how evapotranspiration across the plateau has changed over the past two decades.

 

Evapotranspiration is the loss of water from soil both by evaporation from the soil surface and by transpiration from the leaves of plants growing on it. It is crucial for the exchange of water and energy between the land surface and the atmosphere as it consumes around two-thirds of global terrestrial precipitation.

 

The western part of the Tibetan Plateau, also known as Earth’s “Third Pole,” saw a decrease in annual evapotranspiration from 2001 to 2018, but evapotranspiration over the eastern part of the plateau rose over the same period, according to the study , which was published by Earth System Science Data. 

 

Overall, evapotranspiration increased slightly from 2001 to 2012 on the plateau. However, it declined significantly after 2012 and reached its lowest level in 2014, according to the study.

 

Previous studies have used changes in precipitation, runoff, and soil moisture to show that the water cycle across the Tibetan Plateau has intensified over the past century as global temperature has increased. But those studies did not clarify the spatial distribution and temporal changes in evapotranspiration.

 

“Therefore, understanding the climatic, spatial, and temporal changes of evapotranspiration over the Tibetan Plateau is important for understanding the water cycle and the deployment of water resources in the region,” said Prof. Ma Yaoming, corresponding author of the study and a researcher at the Institute of Tibetan Plateau Research of the Chinese Academy of Sciences. “The results of the study will lay a scientific basis for the accurate assessment of the water balance on the Tibetan Plateau.”

 

The researchers also found that declines in annual evapotranspiration were substantial in spring and summer, but almost no visible trends were detected in autumn and winter.

 

They adopted on-site observations, satellite-based data, and meteorological forcing data to estimate monthly evapotranspiration across the research area.

 

The dataset is available without charge at the Science Data Bank and at the National Tibetan Plateau/Third Pole Environment Data Center.

 

Editor’s note: This study was supported by STEP, a TPE-related science project.