About global warming. greenhouse effect
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Greenhouse effect
The greenhouse effect is caused by the increase in the content of greenhouse gases (carbon dioxide, methane, etc.) in the atmosphere.
The air contains carbon dioxide, and the levels have remained essentially constant over long periods of time. This is because the carbon dioxide in the atmosphere is always in a dynamic equilibrium state of "growing and consuming". 80% of the carbon dioxide in the atmosphere comes from the respiration of humans, animals and plants, and 20% comes from the burning of fuels. 75% of the carbon dioxide dispersed in the atmosphere is absorbed and dissolved in water by ground water and aerial precipitation in oceans, lakes, rivers, etc. There is also 5% of carbon dioxide, which is converted into organic matter and stored through plant photosynthesis. This is why carbon dioxide has remained constant at 0.03% (volume fraction) of air for many years.
However, in recent decades, due to the rapid increase in population and rapid industrial development, the carbon dioxide produced by breathing and the carbon dioxide produced by the combustion of coal, oil, and natural gas have far exceeded past levels. On the other hand, due to the indiscriminate deforestation, a large amount of farmland has been built into cities and factories, destroying vegetation and reducing the conditions for converting carbon dioxide into organic matter. In addition, surface waters are gradually shrinking and precipitation is greatly reduced, which reduces the conditions for absorbing dissolved carbon dioxide and destroys the dynamic balance of carbon dioxide generation and transformation, causing the carbon dioxide content in the atmosphere to increase year by year. The increase in carbon dioxide content in the air has caused changes in the earth's temperature.
Nitrogen and oxygen have the highest proportions in the air, and they can both transmit visible light and infrared radiation. But carbon dioxide cannot pass through infrared radiation. Therefore, carbon dioxide can prevent surface heat from radiating into space and has the function of regulating the earth's temperature. Without carbon dioxide, the Earth's average annual temperature would be 20°C lower than today. However, if the carbon dioxide content is too high, the earth will seem to be in a pot, and the temperature will gradually rise, forming a "greenhouse effect." In addition to carbon dioxide, there are other gases that form the greenhouse effect. Among them, carbon dioxide accounts for about 75%, chlorofluoroalkane accounts for about 15% to 20%, and there are more than 30 kinds of methane, nitric oxide, etc.
The greenhouse effect is a phenomenon in which global temperatures rise due to an increase in the content of carbon dioxide and other gases in the atmosphere. If carbon dioxide content doubles compared to today, global temperatures will rise by 3 to 5 degrees Celsius, and the polar regions may rise by 10 degrees Celsius, and the climate will become significantly warmer. Rising temperatures will lead to increased rainfall in some areas, droughts in some areas, stronger and more frequent hurricanes, and intensified natural disasters. What is even more worrying is that as temperatures rise, glaciers in the polar regions will melt and sea levels will rise. Many coastal cities, islands or low-lying areas will face the threat of rising seawater, or even be engulfed by seawater. 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 1.5 million people died from starvation.
This is a typical example of the disaster caused by the "greenhouse effect" to mankind. Therefore, we must effectively control the increase in carbon dioxide content, control population growth, use fuels scientifically, strengthen afforestation, green the earth, and prevent the huge disaster caused by the greenhouse effect to the world.
Carbon dioxide is an important aspect affecting the earth's energy balance. Energy mainly reaches the earth in the form of light, most of which is absorbed and converted into heat in various ways. The heat is finally re-radiated from the earth in the form of infrared (thermal) radiation. In the atmosphere, nitrogen and oxygen account for the highest proportions, and they can both transmit visible light and infrared radiation. Carbon dioxide does not hinder light radiation, but it can absorb infrared rays and block the passage of infrared rays. Just like the glass roof of a greenhouse, it is easy for energy to enter but difficult to escape. The more carbon dioxide in the atmosphere, the greater the obstruction to the escape of heat from the earth to outer space, thereby causing the earth's temperature to rise faster. This phenomenon is called the greenhouse effect.
Scientists predict that every time carbon dioxide in the atmosphere doubles in the future, the global average temperature will rise by 1.5 to 4.5 degrees Celsius, and the temperature rise in the polar regions will be about three times higher than the average. Therefore, rising temperatures will inevitably partially melt the polar ice, causing sea levels to rise. The impact of sea level rise on human society is very serious. If the sea level rises by 1 m, the directly affected land will be about 5×106 km2, the population will be about 1 billion, and the cultivated land will account for about 1/3 of the world's total cultivated land. If extremely large storm surges and salt water intrusion are taken into account, coastal areas below 5 m above sea level will be affected. The population and food production in these areas account for about 1/2 of the world. Some coastal cities may have to move inland, and most coastal plains will become salty or swampy, making them unsuitable for food production. At the same time, it will also cause disasters to the middle and lower reaches of the river. When seawater intrudes, it will cause the water level of the river to rise, accelerate sedimentation, intensify the threat of floods, and drastically worsen the environment in the lower reaches of the river. The greenhouse effect and global warming have aroused widespread concern around the world. Currently, the formulation of an international climate change convention is being promoted, and reducing carbon dioxide emissions has become a general trend.
The atmosphere is the air layer surrounding the earth. It is composed of nitrogen, oxygen, argon and other gases. When the sun passes through the air, the solar radiation energy is weakened by them to varying degrees, forming the current balance. The earth's climate system is in a state of flux, and humans have adapted to this state. However, with the development of production and the advent of the industrial revolution, various human activities have caused changes in certain components in the air, breaking this balanced state. For example: carbon dioxide, methane, nitrous oxide, chlorofluorocarbons, and ozone. These gases are almost transparent to short-wave radiation from the sun, but have strong absorption effects on long-wave radiation emitted from the ground, making the surface radiation The heat remains in the atmosphere and acts like a glass cover or plastic greenhouse in a greenhouse, raising the temperature of the earth's surface, often called the "greenhouse effect." This greenhouse effect changes the original ecological environment. According to research by scientists: after doubling carbon dioxide, the global average surface temperature will increase by 2-3°C, polar sea ice will melt, global sea levels will rise significantly, precipitation processes will also increase, and the distribution will be uneven, and the resulting global ecosystem will also There will be huge changes. In addition, chlorofluorocarbons such as Freon (refrigerator refrigerant) not only have a strong warming effect, but also damage the ozone layer and cause the so-called ozone hole. Ozone is an element that can prevent ultraviolet radiation in solar radiation from reaching the ground. Its reduction causes the ground to The amount of ultraviolet radiation increases. Excessive ultraviolet radiation received by the human body will weaken immunity, increase the number of patients with infectious diseases, and increase skin cancer and white miasma diseases
Affected by the greenhouse effect
Affected by Due to the dual impact of the greenhouse effect and periodic rising tides, most of the western Pacific island country of Tuvalu is about to be submerged by sea water, including the capital's airport and some residences and offices.
Since the greenhouse effect will cause the ice and snow in the Arctic and Antarctic to melt and the water level to rise, Tuvalu is a direct threat, so the country has always been very outspoken at international environmental protection conferences. Former Prime Minister Peru once claimed that Tuvalu was "the first victim of global warming."
The greenhouse effect can make prehistoric deadly viruses threaten humans
American scientists recently warned that as rising global temperatures melt the Arctic ice, deadly prehistoric viruses that have been frozen for hundreds of thousands of years It may reappear, causing the world to fall into an epidemic panic and seriously threatening human life.
Scientists from Syracuse University in New York pointed out in the latest issue of "Scientist Magazine" that they had previously discovered a plant virus TOMV. Since the virus spreads widely in the atmosphere, it is inferred that it is in the Arctic ice There are traces of it too. So researchers extracted four ice blocks from Greenland with ages ranging from 500 to 140,000 years old, and found the TOMV virus in the ice. Researchers say the virus is surrounded by strong proteins on its surface, allowing it to survive adversity.
This new discovery leads researchers to believe that a series of epidemic viruses such as influenza, polio and smallpox may be hidden deep in the ice. At present, humans have no resistance to these primitive viruses. When When global temperatures rise and the ice melts, these viruses that have been buried in the ice for thousands of years or more may be resurrected and form epidemics.
Scientists say that although they do not know the survival prospects of these viruses, or their chances of adapting to the terrestrial environment again, they certainly cannot rule out the possibility of a comeback