Wind is one of the two primary agents sculpting the Earth’s landscape, the other being water. Our understanding of aeolian processes is ever expanding from tropical and temperate deserts to cold high-latitude and high-altitude areas.
The Tibetan Plateau is a particularly interesting place to study high-altitude aeolian processes. First, because the characteristics of the region are unique and some of the aeolian processes are quite different from other locations. Second, because aeolian processes on the Tibetan Plateau have an impact far beyond its geographic area, including influencing global climate. Our open access review article, recently published in Reviews of Geophysics, gives an overview of research that has improved our understanding of aeolian processes and landforms on the Tibetan Plateau. Here we give a brief overview of the characteristics and significance of this region.
Aeolian processes in the past on the Tibetan Plateau left extensive aeolian sediments such as loess and fossil aeolian sand, the oldest loess dating back to 800,000 years ago. However, the reconstruction of past aeolian activities is short (mostly since the Late Glacial) and shows wide regional differences because of the overall erosional environment that does not favour the preservation of aeolian records.
Processes that were active in the geological past continue in the present day. However, locations where aeolian processes occur strongly depend on the geomorphological conditions that determine sediment availability.
Therefore, contemporary aeolian processes primarily occur in several dry basins in the northern part of the plateau including the Qaidam Basin, Gonghe Basin and Kumkuri Basin.
Also in wide river valleys such as the Yarlung Zangbo River, headwaters of the Yangtz and Yellow River; on lakeshores such as the Qinghai Lake and Dongi Cona; on mountain slopes; and on gravel pavements.
Studies of aeolian sediment characteristics suggest a local origin. For example, loess on the Tibetan Plateau provides interesting contrasts with that of China’s Loess Plateau, which are transported from arid regions of northwest China.
Aeolian processes form various aeolian landforms but aeolian geomorphology is much simpler on the Tibetan Plateau than other deserts such as those in northwest China due to limited sediment availability and short development history. For example, compound and complex dunes are absent on the Tibetan Plateau.
Aeolian processes on the Tibetan Plateau also exert a direct impact on the earth system because aeolian dust is emitted into the high atmosphere and transported long distances. However, the presence of a cryosphere makes the responses of aeolian processes to global change on the Tibetan Plateau different from those in other areas.
It used to be thought that thawed frozen ground in response to global warming led to the expansion of aeolian desertification. However, it proves that aeolian desertification is not so severe as previously thought because that warming that is accompanied by slightly increased precipitation and reduced wind speed favours the restoration of aeolian desertified lands.
Aeolian desertification in general is driven by climate, though adverse human interferences, such as over-grazing, exert strong impacts in some localities thus aeolian desertification may be less severe in the future.
The location of the Tibetan Plateau means that aeolian processes take place where there is generally low air temperature, low air density, and the presence of a cryosphere. Thus, comparative studies of aeolian physics between the Tibetan Plateau and other areas are necessary to understand the characteristics of aeolian processes that are specific to the plateau, and the effect of freeze-thaw cycles on aeolian processes.
Another direction for comparative study is interplanetary. The wind is possibly active in shaping the landscape of other planets too, such as Mars and Venus, as well as Saturn’s moon, Titan. Recent findings on the Tibetan Plateau of analogues of Martian aeolian landforms have attracted researchers interested in comparative studies of aeolian processes between Mars and Tibetan Plateau.
Although the aeolian processes on the Tibetan Plateau are quite different from elsewhere in the world, it is important to continue research in this area as it will help to improve our understanding of Earth-surface processes and the impacts of climate change.
—Zhibao Dong, Shaanxi Normal University; email: [email protected], with contributions from co-authors