Because people burn fossil fuels, such as oil and coal. Or cutting down and burning down forests will produce a lot of carbon dioxide, that is, greenhouse gases, which have a strong permeability to visible light emitted by the sun, a strong absorption to long-wave radiation emitted by the earth, and a strong absorption of infrared radiation from the ground, leading to an increase in the temperature of the earth, that is, the greenhouse effect.
Global warming will redistribute global precipitation, melt glaciers and frozen soil and raise sea level, which will not only endanger the balance of natural ecosystems, but also threaten human survival.
2. Ozone depletion refers to the phenomenon that ozone is consumed, destroyed and thinned in the ozone dense layer near 25 kilometers. Namely ozone layer destruction.
The atmosphere with high ozone concentration is about 10 ~ 50 km, with the highest concentration at 25 km, forming an ozone layer with an average thickness of 3 mm. It can absorb solar ultraviolet radiation, provide the earth with a barrier against ultraviolet radiation, and store energy in the upper atmosphere to regulate the climate.
The destruction of the ozone layer will make excessive ultraviolet radiation reach the ground, causing health hazards; The change of stratospheric temperature leads to the abnormal climate of the earth, which affects plant growth and ecological balance.
3. The concept of biodiversity Biodiversity refers to a stable ecological complex formed by the regular combination of various organisms (animals, plants and microorganisms) within a certain range.
4. Acid rain is wet deposition in acid deposition, which can be divided into "wet deposition" and "dry deposition". The former refers to all gaseous pollutants or particulate pollutants, and with the rain? 、? Snow? 、? Those that fall to the ground in the form of fog or hail, the latter refers to acidic substances brought by dust falling in the air on days when it doesn't rain. Acid rain can be divided into nitric acid rain and sulfuric acid rain.
5.？ Forest is the main body of terrestrial ecosystem and plays a decisive role in maintaining terrestrial ecological balance. However, in the recent 100 years, the destruction of forests by human beings has reached a very alarming level.
In the early days of human civilization, two-thirds of the earth was covered by forests, about 7.6 billion hectares; /kloc-reduced to 5.6 billion hectares in the middle of 0/9th century; At the end of the 20th century, it dropped sharply to 3.44 billion hectares, and the forest coverage rate dropped to 27%.
The sharp decline of forests has directly led to six global ecological crises.
6. Land desertification refers to land degradation, also called "desertification". 1992 The United Nations Conference on Environment and Development defined desertification as follows: "Desertification refers to land degradation caused by drought disasters in arid, semi-arid and semi-humid areas due to climate change and unreasonable human economic activities.
Land desertification is simply land degradation, also called "desertification".
7. Air pollution refers to the phenomenon that the content of some substances in the atmosphere reaches harmful levels, which destroys the ecological system and the conditions for the normal survival and development of human beings and causes harm to people or things.
Air pollutants enter the atmosphere (input) from artificial or natural sources, participate in the circulation process of the atmosphere, and are removed (output) from the atmosphere through chemical reactions, biological activities and physical sedimentation after a certain retention time.
If the output rate is less than the input rate, it will be relatively concentrated in the atmosphere, resulting in an increase in the concentration of a substance in the atmosphere. When the concentration rises to a certain extent, it will directly or indirectly cause acute and chronic harm to people, organisms or substances, and the atmosphere will be polluted.
8. Marine pollution usually means that human beings have changed the original state of the ocean and destroyed the marine ecosystem. The pollution caused by harmful substances entering the marine environment will destroy biological resources, endanger human health, hinder human activities such as fishing at sea, and destroy the quality of seawater and environment.
The ocean has a vast area and huge water storage capacity, so it has long been the most stable ecosystem on the earth. All kinds of substances flowing into the ocean from land are accepted by the ocean, but the ocean itself has not changed significantly. However, in recent decades, with the development of world industry, marine pollution has become increasingly serious, which has caused great changes in the local marine environment and has a tendency to continue to expand.
9. Water pollution: When the pollutants entering the water body exceed the environmental capacity or self-purification capacity of the water body, the water quality deteriorates, thus destroying the original value and function of the water body. There are two reasons for water pollution: one is natural and the other is man-made.
Water pollution caused by special geological conditions, such as a large number of rich chemical elements, some harmful substances produced when natural plants rot, and various substances carried by rain after falling to the ground into human water bodies, all belong to natural pollution.
10. According to the source, solid waste can be roughly divided into three types: domestic waste, general industrial solid waste and hazardous waste. In addition, there are agricultural solid waste, construction waste and waste soil. If solid waste is not properly collected, utilized and treated, it will pollute air, water and soil and endanger human health.