Study Shows Different Actual Evapotranspiration Expectation in Tarim River Basin when Temperature Rises

Most parts of the earth are undergoing a warming tendency since the end of last century. Simulated results of Intergovernmental Panel on Climate Change show that the air temperature on the surface of the earth will see a growth of 0.7 to 2.4℃.

Global warming has been a hot topic in the recent decade. An agreement was achieved to strive for the limitation of global warming to less than 2.0 °C above pre-industrial levels, after a bitter and tough negotiation.

Scientists from Xinjiang Institute of Ecology and Geography (XIEG) of the Chinese Academy of Sciences found in their recent study on the actual evapotranspiration (ETa) of the Tarim River Basin that, the southwest and northeast may encounter the greatest increases in Eta, when the air temperature rises.

Actual evapotranspiration is the amount of water actually lost by the vegetated surface. It is an important component of the water cycle and plays a key and direct role in influence on climate change.

“Evapotranspiration is a critical link of water cycle between the land surface process and the atmospheric process. It connects the energy budget, the water cycle and the carbon cycling. And that is why we take it into our research on the Tarim River Basin,” said SU Buda, leading researcher of the study.

SU and his colleagues at the XIEG calculated ETa with an advection-aridity model, and analyzed the changes in ETa under global warming scenarios of 1.5 °C (2020 to 2039) and 2.0 °C (2040 to 2059).

Their study showed that when the global temperature rise by 1.5 °C, the the average ETa in the Tarim River Basin will see an increase of 6.9 mm relative to the reference period of 1986 to 2005. Spring and summer encounter more obvious increases than the other two seasons.

The increment in the annual ETa in this region considering a warming of 1.5 °C was 4.3 mm less than that for a warming of 2.0 °C.

“The greatest increases in ETa were projected for the northeast and southwest,” said SU. “It is suggested that the higher ETa under a warming of 2.0 °C mainly results from an increase in the sunshine duration in the southwestern basin and an increase in precipitation in the northeastern basin.”

Research results of the study were published on the recent issue of Atmospheric Research, entitled “Projection of actual evapotranspiration using the COSMO-CLM regional climate model under global warming scenarios of 1.5℃ and 2.0℃ in the Tarim River Basin, China”.