Views: 20 Author: XICHENG EP LTD Publish Time: 2021-08-18 Origin: XICHENG EP LTD
The environmental problems that have threatened the survival of mankind and have been recognized by mankind are mainly: global warming, ozone layer destruction, acid rain, freshwater resource crisis, energy shortage, sharp decline of forest resources, land desertification, accelerated species extinction, garbage disaster , Pollution from toxic chemicals and many other aspects.
1. Global warming Global warming refers to the increase in global temperature. In the past 100 years, the global average temperature has experienced two fluctuations of cold-warm-cold-warm, which must be seen as an upward trend. After entering the 1980s, the global temperature has risen significantly. The global average temperature from 1981 to 1990 was 0.48°C higher than 100 years ago. The main cause of global warming is that humans have used a large amount of fossil fuels (such as coal, oil, etc.) in the past century, and emitted a large amount of CO2 and other greenhouse gases. Because these greenhouse gases have a high degree of permeability to short-wave radiation from the sun, and a high degree of absorption for long-wave radiation reflected from the earth, which is commonly referred to as the greenhouse effect", leading to global warming. Global warming As a result, global precipitation will be redistributed, glaciers and frozen soil will melt, sea level will rise, etc., not only endangering the balance of natural ecosystems, but also threatening human food supply and living environment.
2. Destruction of the ozone layer There is an ozone layer in the stratosphere that is about 20 to 30 kilometers near the ground in the earth's atmosphere. The ozone content accounts for one hundred thousandth of the total amount of gas at this height. Although the content of ozone is extremely small, it has a strong function of absorbing ultraviolet rays. Therefore, it can block the damage of solar ultraviolet radiation to life on the earth and protect all life on the earth. However, some pollutants emitted by human production and life, such as chlorofluorocarbon compounds in refrigerators, air conditioners and other equipment refrigerants, and chlorofluorocarbon compounds for other purposes, can be intensified after being irradiated by ultraviolet rays and become very active. The strong atoms interact with the ozone (O3) of the ozone layer to turn it into oxygen molecules (O2). This action occurs in a chain, and the ozone is rapidly depleted, causing the ozone layer to be destroyed. The hole in the ozone layer in Antarctica is one of the most significant signs of ozone layer destruction. By 1994, the destruction of the ozone layer over Antarctica had reached 24 million square kilometers. The ozone layer over Antarctica was formed in 2 billion years, but it was destroyed by 60% in a century. The ozone layer over the northern hemisphere is also thinner than ever before. The ozone layer over Europe and North America has decreased by 10-15% on average, and the ozone layer over Siberia has even decreased by 35%. Therefore, scientists warn that the destruction of the ozone layer above the earth is far more serious than most people think.
3. Acid rain Acid rain is acid precipitation with a pH value of less than 5.6 caused by acidic pollutants such as sulfur dioxide (SO2) and nitrogen oxides (NOx) in the air. In areas affected by acid rain, there have been a series of serious environmental problems such as acidification of soil and lakes, destruction of vegetation and ecosystems, and corrosion of building materials, metal structures and cultural relics. Acid rain first appeared in Northern Europe and Central Europe in the 1950s and 1960s. At that time, the acid rain in Northern Europe was caused by the migration of industrial acid waste gas from central Europe. Since the 1970s, many industrialized countries have adopted various measures to prevent and control air pollution in cities and industries. The important measure is to increase the height of the chimney. Although this measure has effectively changed the air quality of the emission area, the problem of long-distance migration of air pollutants has become more serious. Distance, forming a wider cross-border acid rain. In addition, the use of fossil fuels around the world has continued unabated, which has further expanded the areas affected by acid rain. Europe, North America and East Asia are seriously affected by acid rain in the world. In my country in the 1980s, acid rain mainly occurred in the southwestern region. By the mid-1990s, it had spread to the south of the Yangtze River, east of the Qinghai-Tibet Plateau, and the Sichuan Basin.
4. Freshwater resource crisis Although two-thirds of the earth's surface is covered by water, 97% is undrinkable seawater, and less than 3% is freshwater, of which 2% is sealed in polar glaciers. Among the only 1% fresh water, 25% is industrial water, 70% is agricultural water, and only a small part is available for drinking and other domestic purposes. However, in such a water-scarce world, water has been abused, wasted and polluted in large quantities. In addition, the uneven regional distribution has led to widespread water shortages in the world, and the global freshwater crisis has become increasingly serious. At present, more than 100 countries and regions in the world are short of water, 28 of which are listed as severely water-deficient countries and regions. It is predicted that in another 20-30 years, there will be 46-52 countries and regions with severe water shortages, and 2.8-3.3 billion people will suffer from water shortages. The vast northern and coastal areas of my country are seriously lacking in water resources. According to statistics, the total area of water-deficient areas in northern my country is 580,000 square kilometers. Among the more than 500 cities in the country, more than 300 are short of water, with an annual water shortage of 5.8 billion cubic meters. These water-scarce cities are mainly concentrated in North China, coastal and provincial capitals, and industrial cities. Water is inseparable from any kind of organism in the world. People aptly compare water to "the source of life". However, with the rapid growth of the population on the earth and the rapid development of production, water has become more precious than ever. The depletion of some rivers and lakes, the depletion of groundwater and the disappearance of wetlands not only pose a serious threat to human survival, but many organisms are also being affected by the diversion of rivers, the drying of wetlands and the deterioration of the ecological environment caused by human production and life. Extinct. Many big rivers, such as the Colorado River in the United States and the Yellow River in China, are no longer in strong winds. The magnificent scene of "running to the sea without returning" in the past has become a memory of history.
5. Shortage of resources and energy At present, the shortage of resources and energy in the world has appeared in most countries and even on a global scale. The emergence of this phenomenon is mainly caused by the unplanned and unreasonable large-scale exploitation of human beings. In the early 1990s, the total energy consumption in the world was about 10 billion tons of standard coal. It is predicted that energy consumption will double by 2000. Judging from the current development of oil, coal, water conservancy and nuclear energy, it is very difficult to meet this demand. Therefore, before major breakthroughs have been made in the development and utilization of new energy sources (such as solar energy, fast neutron reactor power stations, nuclear fusion power stations, etc.), the world's energy supply will become increasingly tight. In addition, the reserves of other non-renewable mineral resources are also declining, and these resources will eventually be exhausted.
6. The sharp decline of forests. Forests are an important part of the ecosystem on which mankind depends. There used to be 7.6 billion hectares of forests on the earth, which fell to 5.5 billion hectares in this century, and by 1976 it had been reduced to 2.8 billion hectares. Due to the growth of the world’s population, the demand for arable land, pasture, and wood has increased, leading to excessive logging and reclamation of forests, causing unprecedented destruction of forests. According to statistics, about 12 million hectares of forest disappear every year in the world, of which the vast majority are tropical rain forests that are vital to the global ecological balance. The destruction of tropical rain forests mainly occurs in developing countries in the tropics, especially the Amazon in Brazil. The Amazon forest ranks first among tropical rain forests in the world. However, by the early 1990s, the forest coverage in this area was reduced by 11% compared to the original, equivalent to 700,000 square kilometers. On average, it was almost the size of a football field every 5 seconds. The forest disappeared. In addition, tropical rain forests in the Asia-Pacific region and Africa are also being destroyed.
7. Land desertification Simply put, land desertification refers to land degradation. In 1992, the United Nations Conference on Environment and Development defined the concept of desertification as follows: "Desertification is due to factors such as climate change and unreasonable human economic activities that have caused land in arid, semi-arid, and sub-humid areas with drought disasters to occur. Degradation. On June 17, 1996, on the second World Day to Combat Desertification and Drought, the Secretariat of the United Nations Convention to Combat Desertification issued a communiqué stating that the phenomenon of desertification in the world is still increasing. There are currently more than 1.2 billion people directly threatened by desertification in the world. 135 million people are in danger of losing their land in a short period of time. Desertification is no longer a purely ecological and environmental problem, but has evolved into an economic and social problem. It has brought poverty and social instability to mankind. As of 1996, The global desertification land has reached 36 million square kilometers, accounting for 1/4 of the entire earth’s land area, which is equivalent to the total area of Russia, Canada, China and the United States. There are more than 100 countries affected by desertification in the world. The people are fighting against desertification, but desertification is expanding at a rate of 50,000 to 70,000 square kilometers per year, which is equivalent to the area of Ireland. By the end of the 20th century, the world will lose about one-third of the cultivated land. There are many people today. Among the environmental problems in China, desertification is one of the most serious disasters. For people threatened by desertification, desertification means that they will lose the most basic basis for survival-the disappearance of productive land.
8. Species accelerated extinction species refers to biological species. There are 5-10 million species of living things on the earth today. Generally speaking, the rate of species extinction and the rate of species generation should be balanced. However, human activities have disrupted this balance and accelerated the rate of species extinction. According to the World Natural Resources Protection Program, it is estimated that thousands of species of animals and plants will become extinct every year. By 2000, 10-20% of the animals and plants on the earth would be 50 ~1 million species of plants and animals will disappear. Moreover, the rate of extinction is getting faster and faster. The World Wildlife Fund issued a warning: this century, birds will be extinct every year, and in tropical rainforests, at least one species will be extinct every day. The extinction of species will threaten the food supply of the entire planet, and the losses and impacts it will bring to the development of human society are unpredictable and unrecoverable.
9. Garbage disaster The world produces nearly 10 billion tons of garbage every year, and the ability to dispose of garbage is far behind the increase in garbage, especially in some developed countries, which are already in a garbage crisis. The United States is known as a large garbage country, and its domestic garbage is mainly buried by topsoil. In the past few decades, the United States has used more than half of the land that can be landfilled, and 30 years later, the remaining land will also be used up. Our country’s garbage discharge is also considerable. Many cities are filled with garbage mountains, which not only take up a lot of land, but also pollute the environment. The disposal of hazardous wastes, especially toxic and hazardous wastes (including transportation and storage), has caused more serious harm and far-reaching harm, and has become a very difficult environmental problem facing all countries in the world today.
10. Toxic chemicals pollute about 70,000 to 80,000 chemicals on the market. There are about 35,000 species that are harmful to human health and the ecological environment. Among them, there are more than 500 kinds of carcinogenic, teratogenic, and mutagenic effects. With the development of industrial and agricultural production, 1,000 to 2,000 new chemicals are now put on the market every year. Due to the widespread use of chemicals, the world's atmosphere, water bodies, soil and even living things have been polluted and poisoned to varying degrees. Even the penguins of Antarctica have not been spared. Since the 1950s, pollution incidents involving toxic and hazardous chemicals have been increasing. If effective control measures are not taken, it will cause serious harm to humans, animals and plants. Things cause serious harm.