1. The unreasonable use of nature by human beings and the environmental pollution caused by the development of industry and agriculture are all destructive factors to the ecological balance by human beings.

1. Changing species (intentionally or unintentionally causing the disappearance or introduction of species)

For example, in 1859, a farmer brought 25 rabbits from England to Australia, which caused serious damage to the Australian ecosystem because there were no natural enemies.

Another example, In 196, Kaba Forest in Arizona, USA, killed carnivores to protect deer, resulting in a large number of deer breeding and finally no food. On the verge of extinction, etc.

2. The change of environmental factors (a large number of pollutants enter the environment)

3. The destruction of information exchange system (destroying pheromones released by organisms to drive away natural enemies, repel different species, attract the opposite sex, etc.).

2. The factors that destroy the ecological balance include natural factors and human factors. Natural factors such as floods, droughts, earthquakes, typhoons, landslides, Tsunami, etc. The destruction of ecological balance caused by natural factors is called the first environmental problem. The destruction of ecological balance caused by human factors is called the second environmental problem. Human factors are the main reasons for the imbalance of ecological balance. Human factors mainly include the following three aspects: (1) changing environmental factors. For example, human production and life activities produce a lot of waste gas, waste water and garbage, which are continuously discharged into the environment; Unreasonable or predatory use of natural resources by human beings, such as blind land reclamation, deforestation, over-encirclement of water surface, overloading of grasslands, etc., will worsen the environmental quality, have short-term or long-term effects, and make the ecological balance unbalanced. (2) Change the biological species. In the ecosystem, blindly adding a species may destroy the ecological balance. For example, the Welland Canal dug by the United States in 1929 connects interior drainage with the ocean. As a result, the eight-eyed eel entered interior drainage, reducing the annual output of trout from 2 million kilograms to 5, kilograms, which seriously damaged the inland aquatic resources. Losing one species in an ecosystem may also destroy the ecological balance. In the 195s, a large number of sparrows were killed in China, causing serious pests in some areas. The reason is that sparrows, the natural enemy of pests, were killed. Pests have lost their natural inhibitory factors. (3) Destruction of biological information system. Organisms can maintain their clustering and normal reproduction only by information connection with each other. Artificial application of certain substances into the environment interferes with or destroys the information connection between organisms, which may lead to imbalance or destruction of ecological balance. For example, many insects in nature induce male adults of the same species to copulate by secreting released pheromones. If the pollutants discharged into the atmosphere can react with them chemically, the sex pheromone of female insects will lose its physiological activity of attracting male insects, which will inevitably affect the mating and reproduction of insects, and finally lead to the decline or even disappearance of the population. < P > Third, it can be said that it is a great progress for human beings to pay attention to protecting the environment while pursuing their own development. < P > In ancient times, the relationship between human beings and nature was unequal, and human beings were weak. Limited by nature everywhere, but unable to change nature, human beings regard nature as an enemy, and fighting against the sky has become a rare quality, and the spirit of foolish men has been praised for thousands of years.

With the advent of the industrial age, the level of human science and technology has been continuously improved, and the relationship between man and nature has reversed, while "gentle nature" has become an easily injured object. Highly purified chemicals, such as pesticides, paints, etc. Large-scale energy consumption has changed the composition of the atmosphere, thus changing the earth's climate; With the improvement of sanitary conditions, the population has increased sharply, and human activities have greatly destroyed the forest and wetland resources of the earth. As a result, "gentle nature" has become "ferocious nature", and what human beings have imposed on it will eventually be returned to human beings. In areas where water and soil are polluted by highly purified chemicals, the incidence of deformed children and terminal diseases is much higher than normal. Once the oil resources are exhausted, the quality of human life and the normal operation of society will inevitably encounter problems; Abnormal climate will inevitably bring floods or droughts, and famine will also be accompanied by various natural disasters. "ferocious nature" will once again make human beings weak, and the relationship between human beings and nature will return to the starting point.

In order to change this situation, human beings must protect "gentle nature" from further deterioration. Protecting the environment means protecting human beings, which is the industrialization that human beings have experienced. After the extreme expansion of self-confidence, all countries in the world are aware of this problem. Ten years ago, leaders of 178 countries gathered in Rio de Janeiro, Brazil, to discuss environmental protection. The leaders attending the meeting planned to protect the earth's environment, reduce greenhouse gas emissions and promote human welfare and development. In 1997, 16 countries signed the Kyoto Protocol aimed at reducing carbon dioxide emissions in Kyoto, Japan. However, the United States, the largest emitter of carbon dioxide, refused to implement it because reducing emissions hindered economic development. Last year, at the "Earth Summit" held in Johannesburg, South Africa, leaders and scientists continued to discuss plans to improve the environment.

Ten years later, although mankind has made some progress in protecting the environment, differences are still serious. What is the state of the earth now? What kind of attitude should we take to meet the future?

. Cars have also been modified, and the gasoline used has a higher label. After burning, the emission of nitrogen dioxide is greatly reduced. The harm of acid rain in the United States and Western Europe has been greatly reduced. Take Britain as an example, the harm of acid rain has been reduced by half in the past 15 years.

Seven worrying signs

Global warming

Scientists have warned that the increasing emission of greenhouse gases will make the climate change sharply. Sea level rise. According to the statistical report of the National Weather Service, the average temperature in the United States in the three months from November 21 to January 22 was the highest since 1895. Similarly, the average temperature in the three months in the world was the highest since 1895. The direct threat of temperature rise is sea level rise, which will also trigger other extreme weather phenomena. Cause natural disasters.

Uncontrolled demand for oil

There are many rivers on the earth, but there is another river that we don't realize, that is, the river formed by oil. Every day, the river formed by oil surrounds us, and the flow of this river is 11 cubic meters per second. Since the 199s, the world oil consumption has increased by 14%. And it is still increasing. Of the 24 billion tons of carbon dioxide discharged into the atmosphere every year, 4% comes from the burning of oil. In the history of mankind, the content of greenhouse gases in the atmosphere is the highest in 42, years. Two-thirds of the world's oil reserves are concentrated in the Middle East, which has become the most important factor of political and economic instability in this region. Sometimes, people will think that God loves the Middle East too much and gives it such concentrated and rich liquid gold. However, although oil is good, it also brings endless conflicts and disputes to this region. Before the oil is exhausted, such conflicts and disputes seem to have no end.

Gradually disappearing wetlands

Many people actually don't know the importance of wetlands. Wetlands provide habitats for fish, many birds and amphibians and become an important link in the ecosystem. In addition, wetlands have a strong ability to digest pollutants. But around the world, The area of wetlands is shrinking at a high speed. From the Amazon basin in the United States to Iraq, wetlands can't escape the tragic fate. The root cause of the disappearance of wetlands is human agricultural activities, water conservancy activities and other development activities. Reclaiming more cultivated land and building more dams make wetlands gradually disappear. Scientists estimate that the area of wetlands has shrunk by 5% in the past century. 31 years ago, 132 countries signed the Wetland Protection Treaty in Iran. But in fact, the binding force and function of the treaty are quite limited.

The number of super dams is increasing

People think that building super dams shows their ability to transform nature. Indeed, dams transform nature and provide electricity, but they also bring many adverse effects to the environment. Dams change the natural flow direction of rivers. It changed the direction of natural flood discharge. Dams formed unnatural reservoirs on the ground, which affected the natural distribution of fish. In 195, there were about 5, large dams around the world, but by 2, the number of super dams had soared to 45,, and the scale was increasing, which played an increasingly important role in transforming nature. On average, two dams with a height of more than 15 meters were built every day. Most of the newly built dams are located in developing countries. Some giant dams are more than 18 meters high and 15 meters wide. The cost of building such dams is staggering. To flood a large area of land, countless species have to choose other habitats.

There are fewer and fewer coral reefs

Among all marine life, one quarter of the habitats are coral reefs. But in the past 5 years, The number of coral reefs has decreased by 27%. In the El Ni? o phenomenon in 1998 alone, the number of coral reefs in the world suddenly decreased by 16%. The most direct cause of coral reef death is the warming of the sea. Of course, the increase of radiation from the sun in the ocean and the barbaric fishing methods of fishermen are also important reasons for the disappearance of coral reefs.

Overfishing

Human science and technology have made the fishing speed and quantity exceed the natural replenishment capacity of the ocean. As a result, the number of many fish is decreasing sharply, even to the brink of extinction. Now the total number of fish in the ocean is decreasing at a rate of 1% every year. Scientists have proposed to designate specific marine areas as protected areas and stop fishing. Let nature have time and opportunity to rebuild its savings. However, it seems that human beings are unwilling to give nature such an opportunity. Restricting fishing will directly affect fishermen's income and quality of life. However, the fish market only pays attention to price and profit but never considers species protection.

Disposal of nuclear waste

In p>23, more than 44 commercial nuclear reactors around the world will produce more than 11, tons of nuclear waste. How to dispose of these nuclear wastes poses a difficult problem for human beings. First of all, these nuclear wastes are very dangerous. There may be a danger of leakage. Secondly, these nuclear wastes are likely to be obtained by terrorists and used for terrible purposes. There are more than 1 nuclear reactors in the United States, accounting for about 25% of the world's total nuclear waste, and there are even more nuclear waste dumps, with 131 * * *. * * More than 1 million people live within 1 kilometers of the nuclear waste dump. No matter where the nuclear waste is transported, All of them inevitably pollute the local area. The more nuclear energy is used, the more similar pollution will be. When enjoying the super power of nuclear energy, human beings must never forget the hidden worry of nuclear waste.

Seven shocking voices

"At present, human awareness of protecting the earth's resources has never been improved, but the behavior of destroying wildlife habitats on a large scale has not slowed down. I am encouraged by human achievements in science and technology, but, The destruction of species diversity by these scientific and technological achievements has made me desperate. "

-E.O. Wilson, a social biologist at Harvard University

" In terms of environmental protection, the protection of the ocean is relatively backward. Because human beings have always thought that the ocean is so huge and rich, it is hard to imagine how human activities will affect such a giant. Unfortunately, we have caused irreparable damage to the ocean. " Lubchenko, marine ecologist, University of Oregon, USA

"We must admit that in the past 1 years, human's understanding of atmospheric chemical composition has improved a lot. Now almost all people know the term' greenhouse gas' and the exhaust gas emitted by factories and cars causes global climate warming. But people are still ignorant of other hazards of' greenhouse gas', just as they were 1 years ago."

" Roland, atmospheric chemist at the University of California, Avon

"When human beings grow crops, they also destroy the topsoil of the soil. A large amount of topsoil is scraped up and then washed into the ocean with rivers. In the ocean, pesticides and insecticides are accumulating, and the harm to marine ecology is increasing day by day. The key to solve this problem is that human beings should change the types of crops they grow and choose a variety of deep-rooted plants, which is conducive to soil and water conservation."

- Jackson, a crop geneticist, "Greenhouse gases raise the temperature of the atmosphere and the water temperature of the ocean. Once the water temperature of the ocean rises, it will be a global disaster, because the movement of ocean currents will make the water temperature of the oceans around the world as high."

-Richard? Barber, Duke University marine cartographer

"Synthetic chemicals bring convenience to human life, but they are also the culprit that interferes with hormones. Synthetic chemicals are everywhere on the earth, affecting the reproduction and development of human beings and all wild animals. But no country can ban the appearance of synthetic chemicals in shopping malls, and we will continue to suffer from their side effects."

-Ke Erbeng,

, Director of Wildlife and Pollutants Department of the World Wildlife Fund, "The Earth Summit can be said to be a turning point in the issue of human attitude towards nature. I hope people can realize that the protection of species diversity and natural environment such as wetlands and forests will affect the future operation mechanism of the earth."

-Hal? Mooney, an environmental biologist at Stanford University,

7 well-meaning warnings

"If human beings continue their current behavior without making any changes, the number of species on the earth will be reduced by half by the end of the 21st century. If these data can't change human behavior, what will alert human beings?"

-E.O. Wilson, a social biologist at Harvard University

"When asked,' What do you get from nature?' At that time, most people's answers are food, fiber, medicine and genes. But most people don't know the other services provided by the ecosystem. It purifies the air and water, regulates the climate, enriches the barren soil and controls pests and pathogens. Only when we lose these services will we realize their value. "

-Jane? Lubchenko, marine ecologist, University of Oregon, USA

"The El Ni? o phenomenon has aroused people's vigilance, but no one can tell when the next El Ni? o will come again. No one knows whether its consequences are gradual or sudden. If it is sudden, it is natural that we are not prepared to give mankind any opportunities."

-Shirley? Roland, atmospheric chemist at the University of California, Irvine

"The relationship between agriculture and wildlife has been paid attention to, but the relationship between agriculture and the ocean is far from being paid enough attention. It has been warned before that if agriculture is not controlled, the wild world will die. Now I want to warn that if agriculture is not controlled, the ocean will die."

-Weiss