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So far has threatened the survival of mankind and has been recognized by the human major environmental problems: global warming, destruction of the ozone layer, acid rain and fresh water resources crisis, and energy shortages, forest resources is decreasing, the desertification of the land, accelerated species extinction, garbage - disaster, toxic chemical pollution, and many other aspects.
(1) global warming global warming refers to the global warming. Nearly 100 years, the global average temperature has experienced cold - warm - cold - warm twice fluctuations, he will have to look at the rising trend. After the 1980s, the global temperature increased significantly. From 1981 to 1990 the global average temperature over 100 years ago increased by 0.48 ℃. Lead to global warming is the main reason for humanity in nearly a century since the large-scale use of fossil fuels (such as coal, oil, etc.), a large number of CO2 emissions and other greenhouse gases. As a result of these greenhouse gases on the short-wave radiation from the sun with a high degree of permeability, and on the Earth's reflectance by longwave radiation is highly absorbent, which is often say that the greenhouse effect ", leading to global warming. Global warming the consequences of the global precipitation will re-distribution, and permafrost melting glaciers, rising sea levels, endangering not only the balance of natural ecosystems, but also threaten human food supply and living environment.
(2) destruction of the ozone layer in the Earth's atmosphere near the ground about 20 to 30 kilometres of the stratospheric ozone layer, there is a, this highly ozone content of the total gas 1:100,000. Although the ozone concentration is very low, it has a strong UV absorption function, therefore, it can block the solar UV radiation on the Earth's biological harm to the protection of all life on Earth. However, the proction and life of human emissions from some pollutants, such as refrigerators and air-conditioners equipment refrigerant HCFC compounds, as well as other uses of fluoride bromine compounds such as hydrocarbons, and they are UV irradiation may be intensifying, a very active strong atom and the ozone layer, ozone (O3), rendering oxygen molecule (O2), which occurred like a chain effect, the rapid depletion of the ozone, the ozone layer had been destroyed. Antarctic hole in the ozone layer, destruction of the ozone layer is one of the most notable signs. By 1994, the destruction of the ozone layer over the Antarctic area has reached 24 million square kilometers. In the ozone layer over Antarctica is 20 million years old, formed, but in a century, was destroyed by 60 per cent. The ozone layer over the northern hemisphere than any time in the past thin, Europe and North America in the ozone layer over an average of 10 to 15 percent, Siberia and even reced over 35%. So scientists warned that the Earth's ozone layer over the extent of the damage than most people imagine to the more serious.
(3) e to acid rain acid rain in the air of sulfur dioxide (SO2) and nitrogen oxides (NOx) and other pollutants caused by acidic pH of less than 5.6 of acidic precipitation. By acid rain harm region has the acidification of soil and lakes, vegetation, and the destruction of ecosystems, building materials, metal structures and artifacts were a series of serious corrosion, and so on environmental issues. Acid rain in the 1950s and 1960s first appeared in the Nordic and Central Europe, the Nordic acid rain at the European Central acidic instrial emissions in those migration since the 1970s and, in many instrialized countries have taken various measures to combat urban and instrial air pollution, An important measure is to increase the height of the chimney, although this measure effectively changes in the atmospheric emissions quality of the environment, but the long-range transport of air pollutants the problem is more serious pollutants across the borders into neighbouring countries, and even floating very far away distance, and formed a more wide range of multinational acid rain. In addition, the use of fossil fuels worldwide volume increasing, but also makes the harms caused by acid rain areas further expanded. Global seriously harmed by acid rain in Europe, North America and East Asia. China in the 1980s, acid rain occurred mainly in the southwestern region, to the mid-1990s, has been developed to the south of the Yangtze River, east of the Qinghai-Tibet Plateau and the Sichuan Basin, a vast area.
(4) the Earth's surface freshwater resources crisis Although 2 / 3 covered by water, but not for 97% of the drinking water, only less than 3 percent is freshwater, of which 2% of the seal in the polar ice. In only one percent of fresh water, 25 per cent for instrial water, 70 per cent of agricultural water use, only a small part of life for drinking and other purposes. However, in such a dry world, the water was high levels of abuse, waste and pollution. Furthermore, the regional uneven distribution of the world's water shortage caused the widespread phenomenon of the global freshwater crisis has become increasingly serious. At present the world's more than 100 countries and regions short of water, including 28 countries were classified as serious water shortage countries and regions. Forecast for the next 20 to 30 years, a serious water shortage countries and regions will reach 46 ~ 52, and the water shortage will reach 28 ~ population 3.3 billion people. The vast North and the severe shortage of water resources in coastal areas, according to statistics of the total water shortage in north China area of 580,000 square kilometers. More than 500 cities nationwide, more than 300 cities are short of water, the annual capacity of 5.8 billion cubic meters of water shortage, which mainly focus on urban water shortage in north China, coastal and provincial cities, instrial city. Any one of the world is inseparable from the water, people apt analogy to the water? Quot; the source of life. "However, with the surge in population on Earth, the rapid development of proction, water has become more than ever before precious . some of the depletion of rivers and lakes, groundwater depletion and the loss of wetlands, not only pose a serious threat to human survival, but many are also with the biological proction of human life and the diversion of rivers, wetlands, dry and deterioration of the ecological environment and extinction. many major rivers such as the Colorado River, China's Yellow River have been no glory, the former "torrents into the sea no longer return" has become the magnificent sight of the historical memory.
(5) resources, and energy shortages At present, the world's resources and energy shortages have in most countries, and even within the global scope. The emergence of this phenomenon is mainly human unplanned, large-scale mining in those unreasonable. In the early 1990s the world total energy consumption is about 10 billion tons of standard coal, predicted that the 2000 energy consumption will double. Judging from the current oil, coal, water and the development of nuclear energy, to meet this demand is very difficult. Therefore, in the new energy (such as solar energy, a fast neutron reactor power stations, nuclear fusion power station, etc.) development and utilization has been no major breakthrough before the world's energy supply will become increasingly tense. In addition, other non-renewable mineral resources, reserves are dwindling, these resources will eventually be exhausted.
(6) Forest is the sharp decline of forests for mankind's survival in the ecosystem is an important component. Earth has 76 million hectares of forests, of this century, fell to 5.5 billion hectares, and in 1976 had been reced to 2.8 billion hectares. As the world population growth, farmland, grazing land, the increasing demand for wood, leading to the over-harvesting of forests and reclamation to be an unprecedented forest destruction. According to statistics, around the world every year about 12 million hectares of forest disappear, which accounted for the majority of the global ecological balance of the tropical rain forests is essential. The destruction of tropical rain forests mainly in tropical areas of developing countries, especially Brazil's Amazon is the most serious. Amazon forest in the world's tropical rain forests first, but by the early 1990s the region than the original forest cover decreased by 11%, equivalent to 700,000 square kilometers, with an average of every five seconds, almost a soccer field the size of the forest disappear. In addition, in the Asia-Pacific region, Africa's tropical rain forests are being destroyed.
(7) the desertification of the land simply say that the desertification of the land means land degradation. 1992 United Nations Conference on Environment and Development of the concept of desertification made such a definition: "Desertification is a result of climate change and human activities such as irrational economic factors, the arid, semi-arid and drought disasters of sub-humid areas in the land degradation. June 17, 1996 the second World to Combat Desertification and Drought, the United Nations Secretariat of the Convention to Combat Desertification in a communique pointed out: the current world is exacerbated by the phenomenon of desertification. existing 1.2 billion people worldwide by the direct threat of desertification, there are 135 million people in the short run the risk of losing the land. desertification is no longer a simple question of the ecological environment, but also for the evolution of economic and social problems, it brought to mankind by poverty and social instability. date to 1996, global desertification of land has reached 36 million square kilometers, accounting for the whole of the Earth's land area 1 / 4, or Russia, Canada, China and the United States the total land area. around the world affected by desertification in more than 100 countries, in spite of people with desertification in the protest, but desertification has an annual 5 ~ 70,000 km2 expand at a rate equivalent to the area of Ireland. to the end of the 20th century, the world will lose about 1 / 3 of the farmland. today in many human environmental issues, desertification is one of the most serious disaster. about the threat of desertification people, desertification means that they will lose the most basic foundation for survival - the loss of land proctivity.
(8) accelerated species extinctions of species refers to species. Survive on the planet today with 500 ~ 10 million kinds of biological. Generally species extinction rates and the speed of species generation should be balanced. However, e to human activities undermine this balance, speed up the extinction of species, according to the "protection of the world's natural resources outline" estimates, several thousand kinds of plants and animals become extinct each year, in 2000 the Earth 10 ~ 20% of the flora and fauna that is 50 ~ 1 million kinds of plants and animals will disappear. Moreover, the increasingly rapid rate of extinction. World Wildlife Fund warned: this century extinction of a bird each year, and in the tropical rainforest, every day at least one species extinction. Extinction of species as a whole will bring the Earth's food supply threats, the development of human society and the impact of the loss is unpredictable and irreversible.
(9) garbage proced annually worldwide disaster nearly 10 billion tons of refuse and waste disposal capacity far outpaced the rate of increase of refuse, especially the least developed countries, has a garbage crisis. The United States has been called a big power that garbage, refuse to depend largely on their lives topsoil buried. The past decades, the United States has already used more than half of the land may be landfill, 30 years later, the remaining of this land will be fully utilized. China's emissions of waste is substantial in many cities around at a row over the garbage mountain, in addition to a large amount of land occupied, but also pollute the environment. Hazardous waste, particularly toxic and hazardous waste handling issues (including transport, storage), because of the harm caused more severe, and the more far-reaching harm, and has become the world today faces a very difficult environment .
(10) Toxic chemical pollution on the market about 7 to 80,000 kinds of chemicals. On human health and the environment against the about 35,000 kinds. Among them, carcinogenic, teratogenic, mutagenic effect of about 500 species. With the development of instrial and agricultural proction, and now every year 1000 to 2000 new chemicals enter the market. Because of the extensive use of chemicals, the global atmosphere, water, soil and biological are subject to varying degrees of pollution, poisoned, and even the Antarctic penguins were not spared. Since the 1950s, involving poisonous chemicals pollution incidents have increased, and if we do not take effective preventative measures, humans, animals and plants will pose a serious hazard. Of causing serious harm.

㈡ 与大自然的关系环保公开课

清澈来，明亮的小溪缓缓自地流向山的深处，婉转、欢快的叫声直冲那云霄深处，活泼、热烈的瀑布欢快地跃入潭水深处……
这一幅幅的美景无一不是大自然的杰作。大自然就如一位画家，他自如地挥洒手中的笔墨，描绘出一幅幅人间奇景；大自然又如一位钢琴家，他尽情地敲击手中的琴键，弹奏出一支支美妙的旋律；大自然又如一位魔法师，他尽情地发挥无限的想像力，创造出一个又一个的奇迹。
大自然是什么颜色？绿色？红色？黄色？紫色？……不，大自然是五颜六色的。
然而大自然这位画家总是偏爱于绿色，绿色代表着永恒，象征着和平与永恒。大自然自从诞生的那一刻起，身上就携带有绿色的基因，然而正是这些基因造就了如今生机勃勃的大千世界，同时已孕育着人类这一伟大的智慧生命。大自然这位画家自如地调弄手中其它颜色的油墨来点缀美化这大千世界，红色、黄色等颜色代表繁荣与昌盛，正是因为有了这些颜色基因，大自然才呈现出如今的五彩缤纷与色彩斑斓。
大自然是五颜六色的，那么什么是它生命的真谛呢？
“鱼翔浅底，鹰击长空，驼走大漠”这一派和谐的景象不正透露出大自然生命的真谛吗？