Deserts are not controlled, but protected? | World Day to Combat Desertification and Drought

In recent years, my country has made considerable achievements in desertification control! It can be said to be a major topic of praise for infrastructure maniacs.

Can we also work hard to eliminate all deserts in China like we did in our poverty alleviation campaign? You bet it’s not possible. In addition to the technical issues we mentioned earlier, if we really do this, it may backfire.

First of all, when we talk about the word "desert", many of you may think that it refers to the desert in the northwest. In fact, from a scientific definition, desert refers to a geographical landscape formed under arid climate conditions , composed of sparse xerophytic and super-xerophytic vegetation . According to the differences in the composition of the surface materials, it can be divided into: rock desert, gravel desert (Gobi), sand desert, mud desert, salt desert, etc. Desert is just the largest type among them, so it is often used as the "spokesperson" of desert.

As for why we cannot eliminate deserts, it is mainly because deserts, as a very important part of the terrestrial ecosystem , also have extremely unique functions and are indispensable .

First, deserts can form soil and fix carbon . Strong winds carry the surface soil from one place to another. After the soil has found a new home, it may become fertile soil after growth and development, which can meet the needs of plant growth. You know, China's Loess Plateau is a piece of land formed by sand and dust deposition.

Secondly, the desert can purify and store water . You may have seen water purifiers with several layers of rocks and sand, right? This is similar to the principle of desert water purification. The desert has good permeability. Atmospheric precipitation and snowmelt water can not only purify the water quality through layers of filtration, but also seep into the ground and gather into underground reservoirs. The Badain Jaran Desert in the western part of the Inner Mongolia Autonomous Region adds 500 million cubic meters of groundwater every year.

Also, when it comes to desertification control, many people may think of "sandstorms". Sandstorms are indeed annoying, but the effects of sandstorms are not all negative. They can increase rainfall , fix carbon , and neutralize acid rain . We know that rainfall requires condensation nuclei or ice nuclei, and the fine dust particles can just take on this task. When sand and dust fall into the sea, they can provide rich iron elements for some marine plankton, making them active, and then metabolize a large amount of active dissolved organic carbon into inert dissolved organic carbon. Since the latter has a long metabolic cycle in seawater, it is equivalent to being sealed in the ocean. Otherwise, the ocean is an ecosystem with a strong carbon sink capacity. If the hydroxide ions carried by the dust are neutralized with the acidic ions emitted by industry in the atmosphere, the pH of raindrops in the atmosphere can be made neutral, thereby reducing the formation and deposition of acid rain.

Last but not least, the desert is also home to a large number of rare and unique species and precious wild animals and plants . In the Taklimakan Desert alone, there are wild camels, whooper swans, Przewalski's gazelles, Tarim rabbits, red deer, Lop Nur argali, white-tailed crows and other animals. According to incomplete statistics, there are 82 families, 484 genera and 1,704 species of desert plants in China, most of which are relict, endangered and rare types. Not counting these animals and plants, there are still 2.1 billion people in the world living in deserts or arid areas. Existence is reasonable.

In 2009, my country evaluated the value of desert ecosystems. The results showed that the value of desert ecosystems reached 3.08 trillion yuan, accounting for about 9.05% of my country's GDP that year; in 2018, it reached 4-7 trillion yuan. Since deserts are so "valuable", we certainly can't simply and crudely green them all.

When it comes to the environment, it affects the whole body. Blind desert greening will inevitably lead to the collapse of the desert ecosystem, which is absolutely a tragedy. Therefore, before taking action, full research and deduction is the scientific attitude and truly sustainable.