Why is the weather getting warmer?
In addition to carbon dioxide, methane, ozone, chlorofluorocarbons, water vapor and other gases that play an important role in the greenhouse effect. With the rapid increase of population and the rapid development of industry, the carbon dioxide discharged into the atmosphere has also increased accordingly; Because of a large number of deforestation, the carbon dioxide that forests should absorb in the atmosphere has not been absorbed, and the greenhouse effect has been continuously enhanced because of the gradual increase of carbon dioxide. According to analysis, in the past two hundred years, the concentration of carbon dioxide has increased by 25%, and the average temperature of the earth has increased by 0.5℃. It is predicted that by the middle of the next century, the average temperature on the earth's surface will rise by 1.5-4.5℃, especially in the middle and high latitudes.
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.
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 hurricane intensity and frequency, 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.
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.
Scientists predict that if I start cutting trees moderately now, global warming will be reduced by 5% by 2050.
affect
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".
trait
Greenhouse has two characteristics: the temperature is higher than that outside, and it does not dissipate heat. Glass greenhouses and vegetable greenhouses that can be seen in life are typical greenhouses. Glass or transparent plastic film is used as a greenhouse, so that sunlight can directly shine into the greenhouse and heat the indoor air, and the glass or transparent plastic film can prevent the indoor hot air from emitting outward, thus keeping the indoor temperature higher than the outside and providing conditions conducive to the rapid growth of plants.
result
1) the increase of pests and diseases on the earth;
2) sea level rise;
3) Abnormal climate, increasing ocean storms;
4) The land is dry and the desertification area increases.
Scientists predict that if the earth's surface temperature continues to rise at the current rate, by 2050, the global temperature will rise by 2-4 degrees Celsius, polar icebergs will melt greatly, resulting in a sharp rise in sea level, and some island countries and coastal cities will be submerged, including several famous international cities: new york, Shanghai, Tokyo and Sydney.