Why is the climate abnormal in recent years?
Abnormal weather and climate around the world have attracted special attention and heated discussion from scholars at home and abroad. Although there are different opinions, one thing is certain, that is, the impact of human activities (generally referring to human industrial and agricultural production and the transformation of nature) on the troposphere has destroyed the balance between the "greenhouse" and "sunshade" effects inherent in the atmosphere, which may be the main reason for the abnormal weather and climate.
From the TV photos sent back by the spacecraft or the moon, we can see that the earth is beautiful sky blue, as if wearing a transparent blue "coat", and it is a thick layer of air-the atmosphere surrounds the earth. When sunlight passes through this thick atmosphere, it will be scattered by various gas molecules, water vapor and various dust impurities in the air. Among them, short-wave light such as cyan, blue and purple is much more scattered than long-wave light such as red, yellow and orange. Therefore, the scattered light mainly composed of blue and purple light fills the whole atmosphere, making the atmosphere (sky) appear beautiful blue.
The atmosphere is not only like a beautiful coat, but also makes the earth charming; And like a hard "armor", it blocks and prevents the attack of dying stars and ultraviolet rays, and protects all living things on earth; At the same time, it also has the heat preservation function of "greenhouse" and the heatstroke prevention function of "sunshade", so that the surface and lower atmosphere can maintain a temperature environment suitable for human and various biological activities.
There is a small amount of gas in the air-carbon dioxide, which accounts for only 0.033% of the whole atmospheric volume. But it is not only the guarantee for the survival of green plants, but also plays a peculiar warming role on the earth like the glass in the greenhouse.
Carbon dioxide is almost transparent to the short-wave radiation emitted by the sun, which can make it pass through smoothly and reach the surface, thus increasing the temperature of the surface and the lower atmosphere; However, the long-wave radiation (thermal radiation) emitted from the surface is almost opaque and can be strongly absorbed, thus preventing heat from being emitted into space. In this way, heat can be stored in the atmosphere and the average temperature of the atmosphere can be increased. This effect is the "greenhouse effect". If there is no carbon dioxide in the atmosphere, the "greenhouse effect" will cease to exist, and the average temperature on the earth will drop to MINUS 10 degrees Celsius. Therefore, the increase or decrease of carbon dioxide content in the atmosphere will directly affect the trend of global average temperature.
It is estimated that about one-third of the carbon dioxide increased in the atmosphere every year can not be absorbed by seawater and green plants, but accumulated in the atmosphere. In this way, with the increase of carbon dioxide, the greenhouse effect will become stronger and stronger, which will lead to the higher and higher temperature of the earth, and then increase the evaporation of seawater. The increase of water vapor in the atmosphere further aggravated the greenhouse effect. The increase in temperature forces more carbon dioxide to enter the atmosphere through the temperature effect of the surface. If this chain reaction continues, the earth will eventually become an extremely hot planet like Venus (according to the measurement, the surface temperature of Venus is 500℃).
Fortunately, however, in addition to the greenhouse effect, there is also a "parasol effect" in the earth's atmosphere. This is an opposite effect to the greenhouse effect. This effect is mainly due to the strong absorption of short-wave solar radiation by many solid and liquid dust impurities floating in the atmosphere (collectively referred to as "aerosols"), which reduces the total and direct solar radiation reaching the surface. Therefore, it plays a cooling role on the earth. In this way, the one-way development of the "greenhouse effect" is restrained. It is calculated that if the total solar radiation reaching the surface decreases by 1%, the global average temperature will decrease by 1.2~ 1.5℃.
Therefore, it is precisely because of these two opposite effects in the atmosphere that the earth has maintained a relatively stable temperature. Once this delicate balance relationship is destroyed, it will inevitably lead to the imbalance of weather and climate.
Future climate development trend
The future development trend of weather and climate is a matter of great concern. However, climate change is very complicated, which is the result of the comprehensive action of many factors. It is generally believed that climate change is not only caused by astronomical factors (solar activity, the gravity of planets and satellites, the rotation speed of the earth and the changes of the earth's orbital parameters, etc.). ) and ocean influence mainly depend on the impact of human activities and volcanic eruptions on the troposphere, that is, the imbalance between the "greenhouse effect" and the "parasol effect" caused by it.
According to the accurate measurement and calculation of the atmosphere, the concentration of carbon dioxide in the atmosphere has increased by 15% due to human activities in the past hundred years, and its growth rate has become faster and faster in recent years. It is predicted that by 2050, the concentration of carbon dioxide in the atmosphere will double. The resulting "greenhouse effect" can increase the global average temperature by at least 2℃. And cause a series of chain reactions: the polar ice caps will all melt, the snow line will rise and the glaciers will retreat, which will reduce the surface reflectivity and increase the total radiation; At the same time, the sea water level rises sharply, evaporation increases, and the water vapor content in the atmosphere increases greatly, which further contributes to the "greenhouse effect" and leads to the development of the earth's climate in a warmer direction. It is observed that the increase of carbon dioxide concentration is very consistent with the continuous warming during the northern hemisphere 1880~ 1940.
However, human activities and volcanic eruptions not only increase the carbon dioxide content in the atmosphere year by year, but also produce a large number of solid, liquid and gas substances, which pollute the atmosphere. It is estimated that about 95.8 ~ 2610.5 million tons of pollutants enter the atmosphere every year. Among them, natural pollution (pollution caused by natural processes, such as volcanic dust, seawater splash, forest fire smoke and wind-blown dust, pollen, microorganisms and so on). ) is about 77.3-220 million tons; Man-made pollution (burning fossil fuels, smoke and waste gas from cars and factories, etc.). ) is about1.850 ~ 41.5000 tons. After these substances enter the atmosphere, the "parasol effect" is obviously enhanced, thus inhibiting the "greenhouse effect" and cooling the earth. It has been studied that since the end of World War II, the number of volcanic eruptions has increased from 16~8 times a year before the war to 37~40 times a year, more than doubling! Volcanic eruption seriously pollutes the atmosphere and reduces the transparency of the atmosphere, thus reducing the total and direct solar radiation reaching the surface. Therefore, some people think that the obvious increase in the number of volcanic eruptions may be an important reason for the continuous decline in temperature in the northern hemisphere in the past 30 years.
Basic measures
To sum up, the future climate change trend, in addition to astronomical factors and the influence of the ocean, mainly depends on the concentration of carbon dioxide, the amount of atmospheric pollutants and volcanic activity. If volcanic activity is relatively stable, the temperature appreciation will actually depend on the degree to which the "greenhouse effect" of carbon dioxide and the "parasol effect" of air pollutants cancel each other out. Therefore, we must control the increase of carbon dioxide concentration within a reasonable range, and at the same time try our best to eliminate air pollution and reduce pollutants entering the atmosphere. The most fundamental measure is to change the current energy structure and use "clean energy" with no pollution or less pollution, such as solar energy, atomic energy, wind energy, hydropower and fuel hydrogen. At the same time, large-scale afforestation. It is estimated that forests and green plants treat nearly 654.38+000 billion tons of carbon dioxide for human beings every year, and produce oxygen which accounts for 60% of the oxygen in the air. It also has many functions, such as dust prevention, noise reduction, sterilization, soil and water conservation, soil fertility improvement and climate regulation.