Why does too much carbon dioxide warm the earth?

The greenhouse effect is caused by the increase of greenhouse gases (carbon dioxide, methane, etc.). ) In the atmosphere.

The air contains carbon dioxide, which has remained basically unchanged for a long time in the past. 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 past 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.

In the air, nitrogen and oxygen account for the highest proportion, and both of them can transmit visible light and infrared radiation. But carbon dioxide can't. It cannot penetrate infrared radiation. Therefore, carbon dioxide can prevent the 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 in a pot, and the temperature will gradually rise, forming a "greenhouse effect." Besides carbon dioxide, there are other gases that can also cause the greenhouse effect. Among them, carbon dioxide accounts for about 75%, chlorofluoroalkanes account for about 15% ~ 20%, and there are more than 30 kinds of methane and nitric oxide.

Greenhouse effect is a phenomenon that global temperature rises due to the increase of carbon dioxide and other gases in the atmosphere. If the carbon dioxide content doubles, the global temperature will increase by 3℃ ~ 5℃, and the polar regions may increase by 10℃, and the climate will be obviously warmer. Rising temperature will lead to increased rainfall in some areas, drought in some areas, increased intensity and frequency of hurricanes and intensified natural disasters. What is even more worrying is that due to the rising temperature, glaciers in polar regions will melt and sea levels will rise, and many coastal cities, islands or low-lying areas will face the threat of rising sea water or even be swallowed up by sea water. In the late 1960s, a drought lasted for six years in the pastoral areas of sub-Saharan Africa. Due to lack of food and pasture, livestock were slaughtered, and more than 6.5438+0.5 million people died of hunger.

This is a typical example of the "greenhouse effect" bringing disaster to mankind. Therefore, we must effectively control the increase of carbon dioxide content, control population growth, use fuel scientifically, strengthen afforestation, green the earth, and prevent global disasters caused by the greenhouse effect.

Carbon dioxide is an important aspect that affects the energy balance of the earth. Energy mainly reaches the earth in the form of light, most of which is absorbed and converted into heat in various ways, and heat is finally radiated from the earth in the form of infrared (heat) radiation. In the atmosphere, nitrogen and oxygen account for the highest proportion, and both of them can transmit visible light and infrared radiation. Carbon dioxide does not hinder light radiation, but it can absorb infrared rays and block their passage. Just like the glass roof of a greenhouse, it is easier for energy to come in than to go out. The more carbon dioxide in the atmosphere, the greater the obstacle for heat to escape from the earth to outer space, and the faster the temperature of the earth rises. This phenomenon is called the greenhouse effect.

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. Sea level rise has a very serious impact on human society. 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.

The atmosphere is the air layer around the earth, which is composed of nitrogen, oxygen, argon and other gases. When the sun passes through the air, the solar radiation can be weakened by them to varying degrees, forming the current balanced earth climate system, and human beings have adapted to this state. However, with the development of production and the arrival of industrial revolution, various human activities have changed some components in the air, breaking this balance. For example, carbon dioxide, methane, nitrous oxide, chlorofluorocarbons and ozone are almost transparent to short-wave radiation from the sun, but they have a strong absorption effect on long-wave radiation emitted from the ground, leaving the heat of ground radiation in the atmosphere, acting as a glass cover or a plastic greenhouse, and raising the surface temperature, which is commonly called the "greenhouse effect". This greenhouse effect has changed the original ecological environment. According to scientists' research, if carbon dioxide doubles, the global average ground temperature will rise by 2-3℃, the polar sea ice will melt, the global sea surface will rise sharply, the precipitation process will also increase, and the distribution will be uneven, and the global ecosystem will also undergo tremendous changes. In addition, chlorofluorocarbons, such as freon (refrigerator refrigerant), not only have a strong warming effect, but also destroy the ozone layer, resulting in the so-called ozone hole. Ozone is an element in solar radiation that can prevent ultraviolet rays from reaching the ground, and its reduction increases the amount of ultraviolet radiation on the ground. Excessive ultraviolet radiation will weaken human immunity, increase the number of patients with infectious diseases, and increase skin cancer and pudendal diseases.

The influence of greenhouse effect

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".

The greenhouse effect will make prehistoric deadly viruses threaten human beings.

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, human beings have no resistance to these primitive viruses. When the global temperature rises and the ice melts, these viruses buried in the ice for thousands of years or more may resurface 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.

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