Without the Sahara Desert, perhaps there would be no Amazon rainforest?

Review expert: Ye Haiying, deputy director of the New Media Center of the Meteorological Publicity and Science Popularization Center of the China Meteorological Administration (China Meteorological News Agency)

Our impression of the desert is still that of a vast land with “winds blowing for tens of thousands of miles through Yumen Pass”, and we always associate it with desolation, barrenness, monotony and withering, and regard it as a devil’s realm that people try to avoid.

But it is very likely that our "misunderstanding" of the desert is farther than the distance between us and Yumen Pass, and even larger than the Sahara Desert. Without the desert, the earth on which we depend for survival would be a completely different scene.

Today, let us learn about the desert that is thousands of miles away, yet so close.

Image source: Baidu

Can't tell the difference between "荒荒" and "漠漠"?

When it comes to desert, many people immediately think of sandstorms, with blowing sand and dust all over the sky, making it hard to open your eyes when you go out. But the concept of desert is much broader than that.

Desert is a landform with no vegetation on the earth's surface. There are many types of deserts, which are covered by other substances due to the lack of vegetation on the surface. They include rock deserts (stone deserts), gravel deserts (Gobi deserts), mud deserts (mud deserts), and salt deserts (salt deserts ).

Even in the broad sense of desert, those ice fields covered by glaciers in the high-latitude regions of the Arctic and Antarctic have no vegetation and are very barren, so they are called "ice deserts", which refers to deserts composed of glaciers .

Types of deserts Source: Baidu Images

No Sahara Desert

Maybe there is no Amazon rainforest?

Deserts are an indispensable part of the world's terrestrial ecosystem and have extremely unique functions. Recent studies have found that deserts have made outstanding contributions in the following aspects.

Terrestrial ecosystem Source: China Digital Science and Technology Museum

First, deserts can increase rainfall, fix carbon, and neutralize acid rain through the dust effect .

Rainfall enhancement

Dust acts as cloud condensation nuclei or ice nuclei, and can change the size of cloud droplets through interaction with clouds, thereby increasing regional rainfall;

Carbon Sequestration

Dust drifting into the ocean also provides abundant iron for the growth of some marine mayflies, fixes a large amount of carbon dioxide in the atmosphere, and makes the ocean an ecosystem with a strong carbon sink capacity on Earth.

Neutralize acid rain

The hydroxide ions carried by dust neutralize the acidic ions emitted by industrial industries in the atmosphere, making the pH of raindrops in the atmosphere neutral, thereby reducing the formation and deposition of acid rain.

Schematic diagram of sandstorms participating in the earth's cycle Source: Beijing Science and Technology News Agency

Scientists have discovered that 182 million tons of dust are blown up every year in the northern Sahara Desert, moving westward along the atmospheric circulation all the way to the Atlantic Ocean.

The fine particles suspended in the air help the moisture in the atmosphere to condense, forming atmospheric precipitation, which nourishes the large area between the inland and the ocean. Some of the dust falls after crossing 2,500 kilometers over the Atlantic Ocean, and the nutrients it carries promote the growth of marine plankton in this area.

There are also about 132 million tons of dust that can reach South America on the other side of the Atlantic Ocean with the air currents. Among them, 27.7 million tons of dust will fall into the Amazon rainforest. These dusts are rich in nutrients such as nitrogen, phosphorus, and iron, becoming the "fertilizer" necessary for the growth of tropical rainforest vegetation.

Therefore, the existence of deserts has also affected the ecological environment of tropical rainforests to a certain extent .

Tropical rainforest source: Baidu pictures

Secondly, deserts can form soil and sequester carbon . Strong winds carry the topsoil from one place to another, and when it falls on land, it develops and is "reborn", forming fertile soil that can meet the needs of plant growth.

The soil on my country's Loess Plateau is fine-grained, loose, and rich in mineral nutrients, making it very suitable for farming. It is the product of sand and dust deposition.

Finally, the desert can also store and purify water . The desert has good permeability, and atmospheric precipitation and snowmelt water are filtered through layers, which is similar to the principle of a water purifier. It can not only purify the water quality, but also seep into the ground and gather into underground reservoirs.

The Badain Jaran Desert in western Inner Mongolia Autonomous Region adds 500 million cubic meters of groundwater every year.

Water purifier filtration principle Source: Baidu Image

One word makes a big difference

There is only one letter difference between "desert" and "desertification", but our attitudes towards them are very different - deserts need to be protected, and desertification needs to be prevented and controlled.

Desertification refers to land degradation in desert areas caused by multiple factors such as climate change and human activities.

The desertification process affected by climate change is like nature playing a prank on us, making the already arid desert environment even worse. It mainly manifests itself in the following forms:

First, when the wind blows, the sand is carried away and turned into a desert, which is wind erosion desertification (also known as desertification); second, rain erosion causes soil erosion, which is water erosion desertification ; third, the weather is cold, forming perennial or seasonal frozen soil, which is freeze-thaw desertification ; fourth, there is too much salt in the land, forming saline-alkali land, which is salinization desertification .

However, human activities such as excessive agricultural reclamation, overgrazing, excessive logging, improper use of water resources, and lack of attention to environmental protection in industrial, mining and transportation construction will destroy the balance of the land, leading to vegetation destruction and reduced soil productivity, and thus causing desertification .

Desertification will cause the reduction of available land resources, serious decline in land productivity, and intensification of natural disasters. The most direct impact on us is the reduction of grain production. According to statistics, the direct economic losses caused by desertification in my country are about 54 billion yuan each year (data source: Beijing Science and Technology News Agency), which is equivalent to three times the annual fiscal revenue of the five northwestern provinces (regions), and the annual grain production is reduced by more than 3 billion tons.

Therefore, although deserts have important value, excessive desertification can also cause ecosystem imbalance, and we need to take preventive measures.

Although the desert is thousands of miles away from us, it is closely related to us, just like a heartbeat. Every grain of sand in the desert is a witness of life. They may have been part of the oasis, or will soon become part of the oasis.

When distant deserts are facing crises, we should also be deeply worried, because no matter where we are, we share the air of the same planet and jointly maintain the ecological balance and harmony of this planet.

Today is the World Day to Combat Desertification and Drought . Let us sow the hope of life in the vast desert and contribute to the prevention and control of desertification.

Source: Baidu Images