400 words about the greenhouse effect.

Understanding of the concept of 1. 1

The greenhouse effect, also known as the "greenhouse effect", is a common name for the atmospheric heat preservation effect. The atmosphere can make the short-wave radiation of the sun reach the ground, but the long-wave radiation emitted by the ground is absorbed by the atmosphere, which raises the temperature of the ground and the lower atmosphere. Because its function is similar to the greenhouse for cultivating crops, it is named the greenhouse effect. If this effect does not exist in the atmosphere, the surface temperature will drop by about 330℃ or more. On the other hand, if the greenhouse effect continues to strengthen, the global temperature will continue to rise year by year. Since the industrial revolution, carbon dioxide and other endothermic greenhouse gases discharged into the atmosphere have increased year by year, and the greenhouse effect of the atmosphere has also increased, which has caused a series of serious problems such as global warming and attracted the attention of all countries in the world.

1.2 characteristics of "greenhouse"

Greenhouse has two characteristics: the temperature is higher than that outside, and it does not dissipate heat. Glass greenhouses and vegetable greenhouses that can be seen in life are typical greenhouses. Glass or transparent plastic film is used as a greenhouse, so that sunlight can directly shine into the greenhouse and heat the indoor air, and the glass or transparent plastic film can prevent the indoor hot air from emitting outward, thus keeping the indoor temperature higher than the outside and providing conditions conducive to the rapid growth of plants.

1.3 The earth has become a greenhouse.

The air contains carbon dioxide, and the content remains basically unchanged for a long time. This is because the carbon dioxide in the atmosphere is always in a dynamic equilibrium state of "increasing while consuming". 80% of carbon dioxide in the atmosphere comes from the breathing of people, animals and plants, and 20% comes from the burning of fuel. 75% of carbon dioxide scattered in the atmosphere is absorbed by groundwater and atmospheric precipitation such as oceans, lakes and rivers and dissolved in water. Another 5% of carbon dioxide is converted into organic matter through plant photosynthesis and stored. This is why carbon dioxide accounts for 0.03% (volume fraction) of air composition for many years. However, in recent decades, due to the rapid increase of population and the rapid development of industry, the carbon dioxide produced by breathing and burning coal, oil and natural gas has far exceeded the previous level. On the other hand, due to deforestation, a large number of farmland has been built into cities and factories, destroying vegetation and reducing the conditions for converting carbon dioxide into organic matter. In addition, the surface water area is gradually shrinking, the precipitation is greatly reduced, the conditions for absorbing and dissolving carbon dioxide are reduced, the dynamic balance of carbon dioxide generation and transformation is destroyed, and the carbon dioxide content in the atmosphere is increased year by year. The increase of carbon dioxide content in the air changed the temperature of the earth. Carbon dioxide can prevent surface heat from radiating into space and has the function of regulating the earth's temperature. Without carbon dioxide, the average annual temperature of the earth would be 20℃ lower than it is now. But if the carbon dioxide content is too high, it will make the earth seem to be covered in a pot, and the temperature will gradually rise, so the earth will become a "greenhouse".

Advantages and disadvantages of the greenhouse effect

2. 1 Positive effect of greenhouse effect

As we all know, vegetable greenhouses have the function of letting sunlight in and preventing heat loss, which is the so-called "greenhouse effect". There are some trace gases in the earth's atmosphere, such as carbon dioxide, water vapor, methane, carbon monoxide, freon, carbon tetrachloride, sulfur dioxide, ammonia, nitrogen oxides, sulfur and fluorocarbon. They also have similar functions as vegetable greenhouses, that is, they let the short-wave radiation of the sun pass freely, and at the same time, they strongly absorb the long-wave infrared radiation emitted by the ground and the air, thus heating up the near-surface layer. We call these trace gases greenhouse gases and their warming effect greenhouse effect. Another way of saying about the greenhouse effect is that when the light radiated by the sun passes through the atmosphere, it can penetrate carbon dioxide, methane, nitrous oxide, ozone, chlorofluorocarbons and other gases that have the same effect as glass and reach the earth's surface; However, after the sunlight reaching the earth's surface is reflected by the earth's surface, the energy of some long-wavelength rays will be blocked and absorbed by greenhouse gases such as carbon dioxide and water vapor, and it is not easy to be distributed outside the atmosphere near the ground, so that the temperature on the earth will increase with the increase of these tiny greenhouse gases in the atmosphere. Obviously, the existence of a small amount of greenhouse gases in the atmosphere and the appropriate greenhouse effect are indispensable for the survival of kneading dough. If there were no greenhouse gases, the average temperature of the surface layer would be 33℃ lower than it is now, and the earth would become a cold planet. It can be seen that the greenhouse effect is necessary for the survival of life on earth!

2.2 the negative impact of the greenhouse effect

In recent decades, due to the large increase of global population, the rapid development of industry, the increase of cities and their population, the increase of thermal power generation, oil consumption, natural gas consumption and coal consumption, and the deforestation of a large number of forests, some grasses have been degraded due to overgrazing, and many green plant lands have been industrialized and used for industrial construction and construction, especially the development of aquaculture, which will make cattle, sheep and other livestock digest herbivores. Methane, a super greenhouse gas much more powerful than carbon dioxide, spewed out from the mouth. It is precisely because of the above improper activities and behaviors that greenhouse gases such as carbon dioxide, methane, freon, carbon tetrachloride and sulfur dioxide in the earth's atmosphere increase. Many scientists believe that this is an important reason for the frequent occurrence of natural disasters, and that it will have a serious impact on the social and economic development of various countries, and even increase infectious diseases and infectious diseases. Therefore, the governments and people of many countries are very concerned. Many countries have added provisions in their environmental protection laws that should pay attention to reducing greenhouse gases. Many scientific and technological experts in meteorology and environmental protection believe that only when all countries in the world pay attention to reducing greenhouse gases can the greenhouse gas content in the earth's atmosphere be gradually stabilized and the climate around the earth be put on the track of normal change.

Scientists predict that the global average temperature will rise by 1 times for every increase of carbon dioxide in the atmosphere in the future, and the temperature increase in polar regions will be about three times higher than the average. Therefore, rising temperatures will inevitably melt polar ice, leading to rising sea levels. The impact of sea level rise on society is very serious. If the sea level rises 1 m, the land directly affected is about 5× 106 km2, the population is about 1 billion, and the cultivated land accounts for about 1/3 of the total cultivated land area in the world. If extreme storm surge and salt water intrusion are taken into account, the coastal areas below 5 meters above sea level will be affected, and the population and grain output of these areas account for about 1/2 of the world. Some coastal cities may move inland, and most coastal plains will be salinized or swamped, which is not suitable for grain production. At the same time, it will also cause disasters to the middle and lower reaches of the river. Seawater intrusion will cause the river water level to rise, sediment deposition to accelerate, flood threat to intensify, and the downstream environment of the river to deteriorate sharply. The greenhouse effect and global warming have attracted worldwide attention. At present, the international convention on climate change is being promoted, and reducing carbon dioxide emissions has become the general trend.

Affected by the greenhouse effect and periodic tidal waves, most areas of Tuvalu, a western Pacific island country, are about to be submerged by seawater, including the airport in the capital and some houses and offices. Because the greenhouse effect will lead to the melting of ice and snow in the North and South poles and the rising of the horizontal line, which directly threatens Tuvalu, Tuvalu has always been bold in international environmental protection conferences. The former Prime Minister of Peru once claimed that Tuvalu was "the first victim of global warming".

2.3 Serious harm of greenhouse effect

The greenhouse effect caused by environmental pollution refers to the phenomenon that the earth's surface becomes hot. It will bring the following serious consequences:

8? 4. The increase of pests and diseases on the earth;

8? 4 sea level rise;

8? 4. Climate anomalies and marine storms have increased;

8? 4 The land is dry and the desertification area is increased.

Scientists predict that if the earth's surface temperature continues to rise at the current rate, by 2050, the global temperature will rise by 2-4 degrees Celsius, the icebergs in the North and South poles will melt greatly, resulting in a sharp rise in sea level, and some island countries and coastal cities will be submerged, including several famous international cities, such as new york, Tokyo and Sydney.

2.4 The greenhouse effect can threaten the prehistoric deadly virus.

American scientists have recently warned that due to the melting of Arctic ice due to global temperature rise, prehistoric deadly viruses frozen for more than100000 years may reappear, leading to global epidemic panic and seriously threatening human life.

Scientists at Syracuse University in New York pointed out in the latest issue of Scientist magazine that they had discovered a plant virus TOMV earlier. Because it is widely spread in the atmosphere, it is inferred that this virus has also been found in the Arctic ice sheet. So the researchers extracted four pieces of ice from Greenland, ranging in age from 5 million years to 6.5438+0.4 million years, and found the TOMV virus in the ice. Researchers say that the surface of the virus is surrounded by a solid protein, so it can survive in adversity.

This new discovery makes researchers believe that a series of epidemic viruses such as influenza, polio and smallpox may be hidden deep in the ice. At present, kneading is not resistant to these primitive viruses. When the global temperature rises and melts the ice, these viruses buried in the ice for thousands of years or more may revive and form an epidemic. Scientists say that although they don't know the survival hope of these viruses or the chance to adapt to the ground environment again, they certainly can't rule out the possibility of the virus coming back.

3 the impact of kneading activities on the greenhouse effect of natural atmosphere

The influence of kneading activities on the greenhouse effect of natural atmosphere can be divided into two situations: one is to change the content of various greenhouse gases in natural atmosphere, and the other is to change the natural factors of greenhouse effect. With the development of kneading industry, the contents of trace gases such as CO2, CH4 and N2 in the atmosphere are increasing. The data of paleoclimate study show that the changes of CO2 and CH4 contents are highly positively correlated with temperature for a long time, and also show that they once influenced the global climate change during the Paleoglacial as greenhouse factors. Theoretical research and model simulation confirm that the increase of CO2 and CH4 content in the atmosphere will enhance the greenhouse effect of the natural atmosphere and lead to an increase in the global average temperature. The change of greenhouse effect is the result of geothermal equilibrium movement, and any factor that can cause equilibrium movement will cause the change of geothermal temperature. Rubbing affects the heat balance of the ground by changing the reflectivity and hydrothermal characteristics of the underlying surface to solar radiation, which leads to the change of the greenhouse effect of the natural atmosphere.

Vegetation affects the greenhouse effect of natural atmosphere from two aspects. Compared with bare ground, the reflectivity is lower, which increases the absorption of short-wave solar radiation by the underlying surface, and the thermal balance of the underlying surface moves in the direction of temperature increase. On the other hand, the radial leaves of vegetation can store atmospheric precipitation, and the litter of vegetation can also store rainwater, thus increasing the water supply for evaporation and transpiration, and the evapotranspiration of the underlying surface increases, resulting in heat loss, which makes the heat balance of the underlying surface move in the direction of cooling. Therefore, green plants have obvious cooling effect in summer, but not in winter. Therefore, a large area of vegetation destruction, such as deforestation, grassland degradation, land exposure and so on. Will cause changes in the greenhouse effect of the natural atmosphere. Irrigation is an important part of agricultural activities. After irrigation, the soil is moist, the heat capacity is increased, and the water vapor evaporated into the air is also greatly increased. Evaporation absorbs heat energy, which will lead to the cooling of ground and formation air. The cooling effect is particularly prominent in arid areas, and the average temperature of irrigated land is 5~C lower than that in semi-desert areas. Large-scale irrigation can even make some changes in the climate in this area. Land use patterns and changes will also change the water and heat balance of the underlying surface and have an impact on the local climate, such as lake effect of reservoirs, heat island effect of cities and oasis effect of desert reclamation areas. The concentrations of trace gases in the atmosphere, such as CO2, CH4 and NO2, all change obviously, especially CO2 and CH4. The concentrations of CH4 and NO2 are low, which has little influence, so the change of CO2 content becomes the main factor affecting the change of atmospheric greenhouse effect.

4 greenhouse gas effects and the possibility of sudden climate change

In recent years, the mainstream scientific community in the United States insists that it is too early to predict climate change, and if it is inevitable, it will only be decades later. They said that theoretically, under the condition of global warming, the temperature in some parts of the world will rise, but in some areas it will fall. After the global warming, the rainfall in the middle and high latitudes will increase, and the melting of glaciers will inject new water into the ocean. This will affect some ocean currents that transfer heat from tropical areas to the north, such as the Mexican warm current, which will make North America and Europe relatively cold. Of course, even if all this really happens, it will take more than ten years or even decades, because the heat transfer in the ocean is much slower than that in the atmosphere.