Data on the destruction of the earth's environment (simple

At present, the top ten environmental problems that threaten human survival are:

global warming

With the increase of population and the continuous expansion of the scale of human production activities, greenhouse gases such as carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), chlorofluorocarbons (CFCs), carbon tetrachloride (CCl4) and carbon monoxide (CO) are released into the atmosphere, resulting in changes in atmospheric composition. The air quality is affected and the climate is getting warmer. Due to global warming, it will have various effects on the world. Higher temperatures can melt polar glaciers, and the sea level will rise by 6 cm every 10 year, which will flood some coastal areas. Global warming may also affect the changes of rainfall and atmospheric circulation, making the climate abnormal and prone to droughts and floods, which may lead to changes and destruction of ecosystems. Global climate change will have a series of significant impacts on human life.

(b) depletion and destruction of the ozone layer

In the stratosphere 10~50 km from the earth's surface, 90% of the ozone gas on the earth is concentrated, and the ozone concentration is the highest at 25 km from the ground, forming an ozone concentration layer with a thickness of about 3 mm, which is called the ozone layer. It can absorb ultraviolet rays from the sun to protect life on earth from excessive ultraviolet rays, and store energy in the upper atmosphere to adjust the climate. However, the ozone layer is a very fragile atmosphere. If some ozone-destroying gases enter, they will react with ozone and the ozone layer will be destroyed. The destruction of ozone layer will increase the intensity of ultraviolet radiation on the ground and bring great harm to life on earth. Studies have shown that ultraviolet rays can destroy biological protein and genetic material deoxyribonucleic acid, leading to cell death; Increase the incidence of human skin cancer; Injury to the eyes, leading to cataracts and blindness; Inhibit the growth of soybeans, melons, vegetables and other plants. , and penetrate the water layer at the depth of 10 meter, killing plankton and microorganisms, thus endangering the food chain of aquatic organisms and the source of free oxygen, affecting the ecological balance and the self-purification ability of water bodies.

Reduction in biodiversity

The Convention on Biological Diversity points out that biodiversity "refers to all kinds of organisms from all sources, including terrestrial, marine and other aquatic ecosystems and their ecological complexes; It includes diversity within species, between species and between ecosystems. " In the long process of biological evolution, some new species will be produced, and some species will disappear with the change of ecological environment conditions. Therefore, biodiversity is constantly changing. In the past century, due to the rapid increase of population, unreasonable exploitation of resources and environmental pollution, all kinds of creatures and their ecosystems on the earth have been greatly impacted and biodiversity has been greatly destroyed. Some scholars estimate that at least 50,000 biological species are extinct in the world every year, and an average of 140 species are extinct every day. It is estimated that by the beginning of the 265,438+0 century, the global wildlife loss will reach 65,438+05% ~ 30% of the total. In China, due to the pressure of population growth and economic development, the unreasonable utilization and destruction of biological resources, the loss of biodiversity is also very serious, and about 200 species have become extinct; It is estimated that about 5,000 species of plants are on the verge of extinction in recent years, accounting for about 20% of the total number of higher plants in China. About 398 species of vertebrates are also endangered, accounting for 7.7% of the total number of vertebrates in China. Therefore, it is also an important task for us to protect and save biodiversity and the living conditions on which these creatures depend.

(D) the spread of acid rain

Acid rain refers to rain, snow or other forms of precipitation whose PH value is lower than 5.6 in atmospheric precipitation. This is a manifestation of air pollution. The influence of acid rain on human environment is various. Acid rain falling into rivers and lakes will hinder the growth of fish and shrimp in water, leading to the reduction or extinction of fish and shrimp; Acid rain also causes soil acidification, destroys soil nutrition, makes soil barren, damages plant growth, reduces crop yield and damages forest growth. In addition, acid rain will corrode building materials. Relevant data show that in recent ten years, some historical sites in acid rain areas, especially stone carvings, stone carvings or bronze statues, have been destroyed for more than a hundred years, or even more than a thousand years. There are three major acid rain areas in the world. The acid rain area in South China is the only one that has not been treated.

(e) sharp decline in forests.

On today's earth, our green barrier forest is disappearing at an average rate of 4000 square kilometers per year. The reduction of forest destroys its function of water conservation, leading to species reduction, soil erosion and reduction of carbon dioxide absorption, which further intensifies the greenhouse effect.

(vi) Land desertification

The global land area accounts for 60%, of which desert and desertification account for 29%. Every year, 6 million hectares of land become desert. The annual economic loss is $42.3 billion. There are 5 billion hectares of arid and semi-arid land in the world, of which 3.3 billion hectares are threatened by desertification. As a result, 6 million hectares of farmland and 9 million hectares of pastoral areas lose productivity every year. The valleys of Tigris and Euphrates rivers, the cradles of human civilization, have changed from fertile soil to desert. The Yellow River in China has serious soil erosion.

(7) Air pollution

The main factors of air pollution are suspended particles, carbon monoxide, ozone, carbon dioxide, nitrogen oxides and lead. Air pollution causes 300,000-700,000 people to die prematurely every year due to smog pollution, 25 million children suffer from chronic laryngitis, and 4-7 million rural women and children get sick.

(8) Water pollution

Water is what we need most in our daily life, and it is also one of the most contacted substances in the world. However, now even water has become a dangerous thing.

(9) Marine pollution

Human activities have increased nitrogen and phosphorus in coastal waters by 50%-200%; Excessive nutrients lead to a large number of coastal algae growth; Red tides occur in the Baltic Sea, the North Sea, the Black Sea and the East Sea of China. Marine pollution leads to frequent red tides, destroying mangroves, coral reefs and seaweeds, resulting in a sharp decline in fish and shrimp in the offshore area and heavy losses in fisheries.

⑽ Transboundary movement of hazardous wastes

Hazardous waste refers to waste with chemical activity or toxic, explosive, corrosive and other harmful characteristics to human living environment, except radioactive waste. The United States stipulates in the Law of Resource Protection and Recovery that the so-called hazardous waste refers to a mixture of solid waste and several solids, which may lead to or lead to an increase in human mortality or serious incurable diseases or disabilities because of its high quantity and concentration.

The tropical zone of the earth has expanded by 300 kilometers, which has had a far-reaching impact on the ecological environment.

Britain "natural? Earth Science magazine published the research report of the National Oceanic and Atmospheric Administration laboratory. From 1979 to 2005, the tropical area of the earth expanded from 2 latitudes in the north-south direction to 4.8 latitudes, equivalent to 200 to 500 kilometers.

As we all know, the five zones on the earth are actually divided according to astronomical factors, that is, according to the characteristics that when the earth rotates, due to the inclination between the earth axis and the orbital plane, the direct point of the sun hovers north and south of the equator. Generally speaking, the tropics refer to the region between 23.5 degrees south latitude and 23.5 degrees north latitude on the earth.

This research project proves this from four different aspects. According to the research report, this means that the tropical area extends from 225 kilometers to 530 kilometers north and south. Scientists also confirmed that there are more tropical conditions in these areas by measuring the ozone content in the atmosphere, the thickness of the lower atmosphere and the drought in the tropical marginal areas. According to the report, the rapid expansion of tropical areas has a far-reaching impact on the earth's ecological environment, which will lead to more and more storm weather, and the existing arid areas may become more arid.

The main environmental problem in the contemporary world-land desertification

Desertification is the most serious environmental and socio-economic problem in the world today. 199 1 year, UNEP assessed the global desertification situation as follows: the global desertification area has reached nearly 3.6 billion hectares, accounting for about 1/4 of the global land area, affecting 1/6 of the global population (about 900 million people) and 100 countries and regions. Moreover, the speed of desertification expansion is that 6 million hectares of land in the world become desert every year, of which 3.2 million hectares are pasture, 2.5 million hectares are dry land, 6.5438+0.25 million hectares are irrigated land, and another 2.65438+0 million hectares cannot grow food because of degradation. Asia has the most concentrated population affected by desertification in the world, and the countries most affected by desertification are China, Afghanistan, Mongolia, Pakistan and India.

Biodiversity, the main environmental problem in the contemporary world, has fallen sharply.

Scientists estimate that there are about 654.38+04 million species on the earth, but the rate of biodiversity loss on the earth is faster than at any time in history. For example, the extinction rate of birds and mammals may be 654.38+000 times to 654.38+0000 times higher than that of undisturbed nature. The main reasons are seven kinds of human activities: 1, large-scale destruction of forests, grasslands, wetlands and other habitats; 2. Excessive hunting and utilization of wild species resources; 3. Development of urban areas and industrial areas; 4. The introduction or invasion of alien species destroyed the original ecosystem; 5. Uncontrolled tourism; 6. Soil, water and atmosphere are polluted; 7. Global climate change. In the case of accumulation, these activities will accelerate the extinction of biological species exponentially. In the early 1990s, the United Nations Environment Programme (UNEP) made the first assessment of biodiversity, and concluded that 5%-20% of animal and plant populations may face the threat of extinction in the foreseeable future.

The main environmental problem in the contemporary world-the pollution of organic pollutants

There are about11million known chemicals in the world, and at the same time, about 1000 new chemicals enter the market every year. Chemicals are essential raw materials for many large-scale production today, but these chemicals often endanger the environment and ecology in the process of manufacturing, storage, transportation, use and abandonment. At present, the world produces 300 million to 400 million tons of toxic and harmful chemical wastes every year, among which persistent organic pollutants (POPs) are the most harmful to the ecology and widely distributed on the earth, with PCBs and DDT as the most representative ones. These chemical pollutants are released from human industrial and agricultural activities and widely enter the air, land, rivers and oceans. Because these pollutants can be absorbed and accumulated by tiny plankton in the ocean and concentrated millions of times. Fish in the sea can eat these plankton and concentrate them, so the concentration is increased to tens of millions of times. When large marine animals swallow these fish, the concentration coefficient of pollution toxins will increase to hundreds of millions of times. This is because pollution toxins are concentrated in animal fat and it is difficult to excrete them through the body. Through the food chain, these toxins have a strong interference to the marine ecosystem. For example, one of the functions of PCBs is to damage the reproductive system. Some people think that polychlorinated biphenyls (PCBs) are the main culprit that causes the birth rate of Baltic seals to drop by 60% to 80%. These toxins can also cause serious health problems. A few years ago, scientists found that the breast milk of Inuit living in the Arctic contained high concentrations of PCBs, and marine animals such as whales and seals were the main sources of protein for Inuit. When these animals now carry highly polluting toxins, Inuit people's lives are no longer safe. According to the same principle, persistent organic pollutants also have great interference and harm to terrestrial ecosystems, thus becoming one of the main environmental problems concerned by the world at present.

The main environmental problem in the contemporary world-the destruction of forest vegetation

Because of the difficulty of speculation, there is no accurate value of forest area in the world. However, it is estimated that the forest area on the earth is about 3-6 billion hectares, accounting for 20%-40% of the land area, of which about half are tropical forests (including tropical rainforests and tropical monsoon forest) and the other half are mainly coniferous forests in the sub-cold zone. According to the measured dry weight of forest plants, tropical forests are twice as large as coniferous forests in frigid zones, so tropical forests account for a large part of the total biomass on land. However, in the process of industrialization, temperate forests in Europe and North America have been cut down13, so in the past 30 years, developed countries have carried out large-scale tropical forest development on a global scale. European countries entered Africa, the United States entered Central and South America, and Japan entered Southeast Asia, cutting down a large number of tropical forests, and their tropical timber imports increased by more than ten times. The large-scale destruction of forests has caused many environmental consequences, including the change of rainfall distribution, the increase of carbon dioxide emissions, abnormal climate, soil erosion, frequent floods and the decline of biodiversity.

The main environmental problems in the contemporary world-the destruction and pollution of marine resources

It is estimated that 950 million people all over the world regard fish as the main source of protein. However, in recent decades, the over-utilization of marine living resources and the increasingly serious pollution of the ocean by human beings may cause obvious degradation of marine productivity and marine environmental quality on a global scale. 1993, 77.7% of the 1.065438+ billion tons of fish caught in the world came from the ocean. At that time, FAO estimated that more than two-thirds of marine fish were overfished, especially 25% of the fish with data were extinct or endangered due to overfishing, and another 44% of the fish had reached the biological limit. On the other hand, most of the wastes and pollutants produced by human activities eventually enter the ocean. Every year, billions of tons of sludge, sewage, industrial waste and chemical waste are directly discharged into the ocean, and nearly billions of tons of sludge, wastewater and waste are brought into coastal waters by rivers every year, causing changes in coastal habitats and destroying animal habitats and breeding grounds. The main sources and proportions of marine pollution are: urban sewage and agricultural runoff discharge 44%, air pollution 33%, ships 12%, garbage dumping 10%, and offshore oil and gas production 1%.

(Photo) Present Situation of Environmental Pollution on Earth