On the morning of April 15, 2024, Beijing was hit by sand and dust, and the buildings in the urban area were shrouded in floating dust. Visual China / Figure
At 8:26 a.m. on April 15, 2024, a photo posted on Weibo by the Central Meteorological Observatory showed that the familiar yellow color permeated the city of Beijing, but the buildings in the dust were still clearly visible.
Compared with 2023, the dust weather in 2024 seems quiet. According to the classification of sand and dust weather, the familiar yellow can only be defined as "dusty weather". The densely populated areas of northern China have not been "eating soil" positively, and discussions about sandstorms have cooled down on social media.
As early as February 2024, the China Meteorological Administration predicted at a press conference that in the spring of 2024, the number of sand and dust weather processes in northern China will be close to the same period of the year or less, and the sand and dust intensity will be generally weak.
The weakening may be the result of another anomalous weather event. In February 2024, Mongolia, the common source of sandstorms, suffered a severe snowstorm that occurred once in 50 years, and the snow once covered more than ninety percent of the country's land area, according to a number of scholars who analyzed to Southern Weekend. This happens to lead to better soil conditions after the beginning of spring, and the time of sand formation is delayed and the degree is reduced.
This does not mean that the threat of sandstorms is far away. On the contrary, this unusual snowstorm, like the increasingly frequent sandstorms, is also the result of the polarization of the climate under global warming.
Sandstorm "Little Year"
The possibility of dust on April 15 has long been predicted, but in the end it is not very visible. At 6 p.m. on the same day, the blue warning for sandstorms was lifted.
At this point, the fourth dust weather process in 2024 has also come to an end, which lasted about 3 days. According to the classification of sand and dust weather, as long as there is dust, it constitutes sand and dust weather, but only when the horizontal visibility is less than 1 km can it be called a sand and dust storm. In northern China, including Beijing, this spring is dominated by dust or floating dust.
This is a marked difference from the same period in 2023.
At the beginning of 2024, Li Xiang, director of the Atmospheric Environment Division of the Beijing Municipal Bureau of Ecology and Environment, said that 2023 will be the year when Beijing's air quality has been most seriously affected by foreign sand and dust in the past decade. A total of 30 days in the year were directly affected by external sand and dust, among which, a serious sand and dust pollution process occurred in mid-April, resulting in severe pollution of level 6 in 2 days, severe pollution of level 5 in 2 days, and moderate pollution of level 4 in 1 day.
Many experts predict that 2024 has been identified as a "small year" for sandstorms. According to the statistics of Zhang Bihui, director of the Environmental Meteorological Office of the National Meteorological Center, as of April 15, the number of sand and dust weather processes (4 times) in this spring is one less than the average for the same period since 2000, and three times less than that in 2023.
As for the future situation, Liu Yunyun, a researcher at the National Climate Center, said that it is expected that from April to May, the number of sand and dust weather processes in the north of the mainland will be 5-7, close to the same period of the year (6.7 times) or slightly less, and less than the same period in 2023 (9 times), of which there are 1-2 sand and dust storms and strong sand and dust storm processes, and the intensity is generally weak. The average number of dust days is 3-4 days, which is less than the same period in normal year and less than the same period in 2023 (6.8 days).
However, sandstorms still occur in a few areas, such as southern Xinjiang and central and western Inner Mongolia.
On February 17, 2024, at a toll station in Shanshan County, Turpan City, traffic police provided cardboard and tape to "repair" the windows of cars smashed by sand and gravel; on March 27, Inner Mongolia's Xilin Gol League Sunit Right Banner issued a red warning for sandstorms, and the sky was dyed orange by sand and dust, and the local government urgently took measures to suspend work, suspend classes, stop production, and suspend operations; On the afternoon of April 13, the sand and dust at the Mandula port in Inner Mongolia formed a 100-meter "sand wall", and the visibility dropped to less than 500 meters.
Even without the yellow sand, sandstorms threaten human health in a form that is invisible to the naked eye. Mikalai Filonchyk, an associate professor at Lanzhou Jiaotong University's School of Surveying, Mapping and Geoinformatics, noticed that on April 14, the air quality index in Lanzhou was almost always 500.
On March 27, 2024, in the Xilin Gol League of Inner Mongolia, the immigration management police of the Erlian Entry-Exit Border Inspection Station quickly inspected and released customs clearance vehicles in the sandstorm weather. Visual China / Figure
Blizzard lowers the sand?
Unfortunately, the subsidence of extreme weather A may only be a by-product of the rampant extreme weather of B. In Mongolia, a common source of sandstorms, a rare snowstorm indirectly changes the course of sandstorms.
From November 2023 to February 2024, Mongolia continued to suffer from heavy snowfall. According to the International Federation of Red Cross and Red Crescent Societies, the scale of the snow storm is the highest in nearly 50 years. At the time of the disaster, 90% of the country's land was covered with snow, with a maximum depth of 60 centimeters. Some areas were hit by severe cold, with temperatures dropping as low as minus 47°C.
On February 22, 2024 local time, in Mongolia, in cold weather, a traditional yurt tent. Visual China / Figure
There are usually three factors that affect sandstorms: wind intensity, ground soil moisture, and surface vegetation cover. Prolonged snow cover has an impact on the latter two factors. Milley told Southern Weekend that the desert surface covered by heavy snow is not prone to sand, which indirectly reduces the intensity of sandstorms. In addition, the surface ice melts as the weather warms, and the moisture also helps to nourish the vegetation. The root system of these plants is conducive to sand control and soil consolidation, which can also reduce sand formation.
But snowfall doesn't completely eliminate the risk of sandstorms. Wei Ke, an associate researcher at the Institute of Atmospheric Physics of the Chinese Academy of Sciences, told Southern Weekend that if the temperature warms up and the land thaws, sand and dust will still develop. "Since March this year, the temperature in the northern part of the mainland bordering Mongolia has risen relatively high, which is still conducive to the development of sand and dust. So it's hard to say what the dust situation will be in May. ”
Mongolia has a special geographical location, and once desertified land is exposed, it can easily become a source of sand and dust. Milley said Mongolia is located between the Siberian high and the Aleutian low. The Siberian high pressure is dry and cold, which is conducive to the formation of sand particles, while the Aleutian cyclone affects the atmospheric pressure and wind direction, and indirectly affects the intensity and direction of the dust storm.
The key to whether the sandstorm enters China depends on the direction of the Mongolian cyclone. According to Wei Ke, after the disturbance of the westerly wind belt in the mid-latitudes, a counterclockwise Mongolian cyclone will generally form. There will be very strong northwesterly winds at the back of the Mongolian cyclone, like a spinning top, carrying sand and dust from Mongolia into China. The third dust event around 27 March was caused by the eastward movement of the Mongolian cyclone.
The fragile Mongolian plateau
In the winter of Mongolia, there are often snowstorms, so much so that the word "dzud" is used in English to describe the Mongolian snowstorm, which is pronounced as the Mongolian word for "disaster".
There are many types of snow disasters in Mongolia. In addition to the heavy snowfall this winter, another special feature is that the "White Disaster" and the "Iron Disaster" occurred at the same time. A "white plague" is when the snow is too thick for livestock to graze, and an iron plague is when the ground freezes pasture.
Under the snowstorm, herders have become the biggest victims. According to the General Directorate of Emergency Situations of Mongolia, more than 2 million livestock have died as of late February 2024, with lack of forage being the main cause of death. Snowstorms also threaten humanity, with at least 89 reports of missing persons from Mongolia's emergency services from November 2023 to March 2024.
The weather has warmed up, but herders are more afraid of the simultaneous occurrence of drought in summer and snowstorm in winter.
If drought causes forage to be scarce and livestock do not store enough nutrients in the summer, their hopes of surviving the harsh winter are even slimmer. Unfortunately, both drought and severe cold are becoming more common in the Mongolian plateau.
According to a 2018 report by Mongolia's Ministry of Environment and Tourism, the intensity of snow disasters in Mongolia has increased since the 1990s, and winter snowfall is expected to increase by 10 to 14 percent in the future. According to the report's editor-in-chief, Batjargal Zamba, this may be due to the fact that the temperature difference between the cold air and the warmer air in the south has narrowed after the Arctic warms, resulting in the weakening of the polar jet stream formed by the collision between the two, allowing more cold air from the Arctic to enter Mongolia.
On the other hand, the Mongolian plateau is experiencing an unusually high temperature spike. A recent study by Chen Yun, a professor at Yunnan University's Department of Atmospheric Sciences, found that the Mongolian Plateau has become the fastest warming region in the northern hemisphere, three times the average rate. Drought induced by high temperatures kills surface plants and leaves the land dry and loose. Eventually, under the action of the cyclone, it became a sandstorm that crossed the national border.
According to a survey conducted by the Mongolian Academy of Sciences in 2015, 77.8% of the land in Mongolia has been desertified and degraded to varying degrees. There are both climate change and anthropogenic factors behind it. Ma Jun, founder of the Institute of Public and Environmental Affairs, told Southern Weekend that mining and grazing activities in Mongolia over the past few decades have led to severe desertification. "As the global climate warms, the Mongolian Plateau is warming and drying, further exacerbating the vulnerability of this already fragile region." ”
In 2021, Mongolia launched its Billion Trees initiative, which aims to plant one billion trees by 2030. In 2023, Mongolia's forestry department reported that 41.5 million trees had been planted as of October of that year, and that year, Mongolia had stockpiled nearly 63 million tree species and seedlings.
However, it is too early for the public, which has suffered from sandstorms, to be optimistic.
Weike said that the southern region of Mongolia has large areas of the Gobi Desert, and some areas have annual rainfall of less than 50 millimeters, which is not suitable for trees to survive. In areas where trees are suitable for planting, unlike the literal meaning of "shelterbelts", planting trees cannot directly intercept the movement of sand and dust at an altitude of thousands of meters, but mainly to prevent soil erosion and local sandstorming; moreover, the role of shelterbelts will not be effective until more than ten or twenty years later. "China can do more economic cooperation with Mongolia to help Mongolia gradually transform from traditional animal husbandry and mining industries to service and high-tech industries, and vacate the destroyed land." ”
Southern Weekly reporter Hai Duong
Editor-in-charge: Wang Tao