EPOW - Ecology Picture of the Week

Plateau Peaks of Tibet

High Plateau Peaks
South-central Tibet

Explanation:  Here we are, along the twisty, high-altitude roadway between Nangartse and Gyantse in south central Tibet, on the highest plateau on the globe.  And still the snowy peaks stretch ever-higher into the sky.  

To the south of us reigns the Himalayas, and we are not too far from Mount Everest itself.  But here are lessons of both permanence and change.  

It is known that glaciers have been receding in the Himalayas and in the Tibetan Plateau.  But one contributing factor is the reduction in albedo, as indicated in the above photo.  Albedo refers to the degree to which sunlight is reflected off a surface.  A white surface -- as with snow cover, ice caps, and glaciers -- efficiently reflects sunlight.  

But with the loss of that snow and ice cover, the much dark ground surface absorbs sunlight more readily, retaining heat, and accelerating further melting.  It is this "positive feedback cycle" that is one factor causing further and faster loss of snow, ice, and glacial cover here in the high plateau.

In the image above, a glacier has clearly receded (melted back), exposing and depositing ridges of morraine rocks and gravels that it had previously collected on its downslope slide.  

And, above, this classic U-shaped glacial valley, here at the top of the world, stands naked of glacial ice, while the dark ground cover continues to absorb more sunlight and heat.   

And other factors can accelerate loss of albedo and increased warming, including impurities such as carbon and dust deposited in snow and ice.  

Information:
    Li, X., S. Kang, X. He, B. Qu, L. Tripathee, Z. Jing, R. Paudyal, Y. Lie, Y. Zhang, F. Yan, G. Li, and C. Li.  2017.  Light-absorbing impurities accelerate glacier melt in the Central Tibetan Plateau.  Science of the Total Environment 587-588:482-490.
    Zhang, Y., T. Gao, S. Kang, D. Shangguan, and X. Luo.  2021.  Albedo reduction as an important driver for glacier melting in Tibetan Plateau and its surrounding areas.  Earth-Science Reviews 220:103735.