Why does global warming cause a series of abnormal weather?
Causes and effects of global warming
1. Causes of global warming
According to the principles of physics, we know that any object in nature is moving outward Radiant energy, this is called thermal radiation. Generally, the wavelength of thermal radiation from an object has a certain range, which is determined by the absolute temperature of the object. The higher the temperature, the greater the intensity of thermal radiation, and the proportion of short waves is greater; the lower the temperature, the lower the intensity of thermal radiation, and the proportion of long waves is greater. The absolute temperature of the sun's surface is about 6000K, and the strongest band of thermal radiation is the visible light part; the higher the temperature of the earth's surface is 288K, the strongest band of surface thermal radiation is in the infrared region. After solar radiation reaches the earth's surface through the atmosphere, it is absorbed by rocks and soil, and the earth's surface temperature rises; at the same time, the earth's surface materials emit infrared radiation into the atmosphere. The atmosphere has a strong absorption effect on infrared radiation, which causes the earth's surface to gain relatively more heat from solar radiation and lose relatively little heat outside the atmosphere, allowing the earth's surface temperature to be maintained. This is the greenhouse effect of the atmosphere. Eventually, the energy of solar radiation received by the earth and the energy of infrared radiation it dissipates reach a balance, forming the current average temperature on the earth's surface.
As mentioned before, the earth’s atmosphere is a mixture of various gases, of which nitrogen and oxygen account for 99% of the total. However, the greenhouse effect is mainly caused by some trace gases. These gases have a negative impact on the sun. The main part of the radiation - shortwave and visible light - is weakly absorbed, while the longwave radiation emitted from the ground is strongly absorbed. Therefore, when their concentration in the atmosphere increases, the greenhouse effect of the atmosphere will intensify, causing temperatures on the earth's surface and in the lower atmosphere to rise. These gases are called "greenhouse gases". "Greenhouse gases" mainly include carbon dioxide, ozone, methane, chlorofluorocarbons, carbon monoxide, etc. Climate warming in the past century is believed to be the result of a substantial increase in the concentration of greenhouse gases such as carbon dioxide in the atmosphere.
The main cause of the increase in greenhouse gases is human activities. Taking carbon dioxide as an example, in the early 19th century before human society realized industrialization, the concentration of carbon dioxide in the atmosphere was 270 ppm, but by 1988 it had risen to 350 ppm. There are two main reasons for the increase in the concentration of carbon dioxide in the atmosphere: First, due to the rapid increase in population and the development of industrialization, the consumption of fossil fuels by human society has increased sharply, and their combustion produces a large amount of carbon dioxide into the atmosphere, which increases the concentration of carbon dioxide in the atmosphere; secondly, , forest destruction reduces the amount of carbon dioxide absorbed and utilized by plants, resulting in a reduction in the rate at which carbon dioxide is consumed, and also causes an increase in the concentration of carbon dioxide in the atmosphere. Greenhouse gases other than carbon dioxide, such as methane, chlorofluorocarbons (Freon), nitrogen oxides, etc., are also increasing to varying degrees.
2. Possible impacts of global warming
Preliminary research shows that global warming will cause the temperature zone to move northward, which will lead to corresponding changes in atmospheric movement and global precipitation. Changes will follow. Generally, precipitation in existing rainbands will increase at low latitudes, winter snowfall will increase at high latitudes, and summer precipitation will decrease at mid-latitudes. For most arid and semi-arid areas, increased precipitation is beneficial. For areas with reduced precipitation, such as central North America and the inland northwest China, they will become drier and water resources will be more stressed due to the reduction in summer rainfall.
It is estimated that when the global temperature rises by 1.5~4.5°C, taking into account factors such as the thermal expansion of seawater, the increase in Antarctic ice caps due to increased polar precipitation, and the melting of Arctic and mountain ice and snow, , sea level will likely rise by 20 to 165 centimeters. Rising sea levels will undoubtedly change coastlines and have a huge impact on coastal areas. Coastal areas currently at lower elevations will be at risk of being inundated. Rising sea levels will also lead to seawater intrusion, poor flood drainage, land salinization and other consequences.
Although there are many uncertainties, it is obvious that global warming will affect climate zones, precipitation and sea levels, and the resulting impact on human settlements and ecosystems. is extremely complex and must be given due attention. It would be irresponsible to assume that this impact is inconsequential in the long run.