Why is the weather getting hotter in the north?
The carbon dioxide in the atmosphere is like a thick layer of glass, turning the earth into a big greenhouse. It is estimated that without the atmosphere, the average surface temperature would drop to -23°C, while the actual average surface temperature is 15°C. This means that the greenhouse effect increases the surface temperature by 38°C.
The increased concentration of carbon dioxide in the atmosphere prevents the earth's heat from dissipating, causing a perceptible increase in the earth's temperature. This is the famous "greenhouse effect." Gases that destroy the normal relationship between infrared radiation between the atmosphere and the ground and absorb infrared radiation released by the earth, like a "greenhouse", cause the earth's temperature to rise are called "greenhouse gases". Carbon dioxide is the most abundant greenhouse gas, accounting for approximately 0.03% of the total volume of the atmosphere. Many other trace gases also produce greenhouse effects, some of which have stronger greenhouse effects than carbon dioxide.
The atmosphere can make the short-wave radiation of the sun reach the ground, but the long-wave thermal radiation emitted by the surface is absorbed by the atmosphere, which increases the temperature of the surface and lower atmosphere, because it functions like a greenhouse for cultivating crops. , hence the name greenhouse effect. If this effect did not exist in the atmosphere, surface temperatures would drop by about 330C or more. On the contrary, if the greenhouse effect continues to strengthen, global temperatures will continue to rise year by year. Since the Industrial Revolution, the amount of heat-trapping greenhouse gases such as carbon dioxide emitted by humans into the atmosphere has increased year by year, and the greenhouse effect of the atmosphere has also increased. This has caused a series of serious problems such as global warming, which has caused concern in countries around the world. of attention.
In addition to carbon dioxide, gases that play an important role in producing the greenhouse effect include methane, ozone, chlorofluorocarbons, and water vapor. With the rapid increase in population and the rapid development of industry, the amount of carbon dioxide emitted into the atmosphere has increased accordingly; and because forests have been cut down in large numbers, the carbon dioxide in the atmosphere that should be absorbed by the forests has not been absorbed. As carbon dioxide gradually increases, the greenhouse effect continues to increase. . According to analysis, over the past two hundred years, carbon dioxide concentration has increased by 25%, and the earth's average temperature has increased by 0.5°C. It is estimated that by the middle of the next century, the average temperature of the earth's surface will rise by 1.5-4.5℃, with the temperature rising even more in mid- and high-latitude regions.
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.
Greenhouse Effect
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 burning 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. However, some optimistic scientists claim that the carbon dioxide emitted by human activities is far less than that released by geological activities such as volcanoes. They believe that the earth has been active recently, as evidenced by the successive eruptions of Krakatoa and Mount St. Helens. The Earth is releasing carbon dioxide from its belly. So the greenhouse effect is not entirely human’s fault. This view makes some sense, but it cannot explain the sharp rise in carbon dioxide levels after the industrial revolution. Is it all caused by volcanic eruptions?
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.
If the 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.
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.