Background of global warming

198 1~ 1990, the global average temperature increased by 0.48℃ compared with 100 years ago. The main reason for global warming is that humans have used a lot of fossil fuels (such as coal and oil) and released a lot of greenhouse gases, such as carbon dioxide, in the past century. These greenhouse gases cause global warming. In the 20th century, the world average temperature rose by about 0.6 degrees Celsius. In the northern hemisphere, the thawing period of ice and snow in spring is 9 days earlier than that before 150, but the start time of autumn frost is about 10 days. The 1990s was the warmest decade since the mid-Kloc-0/9th century when temperature records began. The hottest years recorded are: 1998, 2002, 2003, 200 1, 1997.

United nations measures after global warming.

In order to stop the global warming trend, the United Nations specially formulated 1992 "United Nations Framework Convention on Climate Change", which was signed into effect in the Brazilian city of Rio de Janeiro in the same year. According to this convention, developed countries agreed to reduce their carbon dioxide and other "greenhouse gases" into the atmosphere to the level of 1990 by the year 2000. In addition, countries with total carbon dioxide emissions accounting for 60% of the global total carbon dioxide emissions in these years have also agreed to transfer relevant technologies and information to developing countries. These technologies and information transferred from developed countries to developing countries will help developing countries actively respond to the challenges brought by climate change. As of May 2004, 189 countries have formally ratified the above convention.

Harm after heating up

The harm of global warming involves all aspects of human existence, from natural disasters to biological chain breakage.

Historical temperature

There are only some temperature records in modern human history. The sources of these records are different, and the accuracy and reliability are also uneven. During 1000-2000 before 1850, although there were warm periods and little ice ages in the middle ages, people always thought that the global temperature was relatively stable. Only in 1860 did the instrument record a situation similar to global temperature, and the influence of urban heat island effect was rarely considered in the records of that year. However, according to the instrument records, during the period from 1860 to 1900, the global average land and ocean temperature increased by 0.75℃; Since 1979, the land temperature has increased by about twice as much as the ocean temperature (the land temperature has increased by 0.25℃, while the ocean temperature has increased by 0. 13℃). In the same year, humans began to use satellite temperature measurement to measure the troposphere temperature, and found that the troposphere temperature rose by 0. 12℃ to 0.22℃ every decade. After 2000, many organizations studied the global temperature in the past 1000 years. Through the comparison and discussion of these research results, it is found that the climate change process since 1979 is very clear. In addition, other research reports show that the average temperature of the earth's surface has increased by about 1. 1F (0.6℃) since the beginning of the 20th century. In the past 40 years, the average temperature has increased by about 0.5f (0.2-0.3℃). In the 20th century, the degree of global warming exceeded any time in the past 400-600 years.

According to the research report of Goddard Space Research Institute of NASA, 2005 was the warmest year since19th century, which was higher than the temperature record of 1998. The World Meteorological Organization and the British Climate Research Institute have similar estimates. On the contrary, their measurement shows that 2005 is the second hottest year after 1998.

After 2000, high temperature records in various places were often broken. For example, on August 1 1 day, 2003, the temperature recorded in Gronau was 4 1.5℃, breaking the record of 139. In August of the same year 10, the temperature in London, England reached 38. 1℃, breaking the record of 1990. In the same period, the lowest night temperature in southern Paris was 25.5℃, breaking the record since 1873. On the night of August 7, Germany also broke the record of the highest temperature in a hundred years. In the summer of 2003, Taipei, Shanghai, Hangzhou, Wuhan and Fuzhou all broke the local high temperature records, while China and Zhejiang broke the high temperature records even faster, and 40 of the 67 weather stations set new records. In July 2004, the rare high temperature in Guangzhou broke the 53-year record. In July, 2005, 200 cities in the United States set a record high temperature. On August 16, 2006, the highest temperature in Chongqing reached 43℃. On July 8, 2006, the temperature in Yilan, Taiwan Province Province reached 38.8℃, breaking the record of 1997. 2006 1 65438+1October1was the hottest day in Hong Kong, with a maximum temperature of 29.2℃, which was 20% higher than the average maximum temperature of 196 1 to 1990.

Research and forecast

According to an article published by the Russian Independent on July 3rd, 2065438, PNAS said that with the sea level rising, about 1400 cities in the United States will be flooded by 2 100. It is reported that this conclusion was made by Benjamin Strauss of the Central Independent Research Center for Climate. According to his research report, by 2 100, global warming will lead to sea level rise 127 cm. By then, about 1400 cities in the United States will face the threat of being flooded.

In this research report, Strauss paid special attention to Florida and Louisiana. He believes that 2.7 million people in Florida 150 cities and Louisiana 1 14 cities will be greatly threatened. In addition, areas threatened by floods include New Jersey, California and North Carolina.

According to the research report of New Scientist magazine, "aerosol method" can reduce the sunlight reaching the ground by one fifth. However, this way will also reduce the blue of the sky, from the familiar blue to white. Ben kravitz of Carnegie Institution of Science in California said that human beings can solve environmental problems by implementing geo-engineering. However, this practice will also have side effects. He pointed out that the diameter of particles ejected into the air is one of 0. 1 to 0.9 micron, which is responsible for reflecting sunlight back into space. However, due to these particles in space, the color of the sky will also change from blue to white.

American scientists found that ancient agricultural activities prevented the world from entering a new ice age. This shows that global warming caused by human activities may have lasted for thousands of years. Researchers said that prehistoric farmers who cut down trees and reclaimed the first field greatly changed the content of greenhouse gases such as methane and carbon dioxide in the atmosphere, and the global temperature gradually rose.

Rudiman, a professor at the University of Virginia in the United States, said: "If it were not for the greenhouse gases brought by early agriculture, the temperature of the earth would probably still be the temperature of the Ice Age." Rudiman admits that the research results are controversial.

The National Center for Atmospheric Research of the United States said on June 5438+07 that scientists predicted through two latest studies that even if the global greenhouse gas emissions were stable at the level of 2000, the trend of global warming and sea level rise in this century would be irreversible.

Scientists from the National Center for Atmospheric Research published two papers in the journal Science on June 5438+08, predicting the trend of global climate change from different angles. Their achievements will be evaluated by the Intergovernmental Panel on Climate Change under the United Nations and included in the next Global Climate Change Report published in 2007.

In the first paper, Wei Gray of the National Center for Atmospheric Research proposed a simple mathematical model to understand global climate change. He believes that due to the "thermal inertia" of the ocean, the response to external influences such as greenhouse gases is lagging behind, and the trend of global warming in this century is only the result of previous greenhouse gas emissions.

It is predicted that by 2400, the greenhouse gas components in the atmosphere will at least increase the global average temperature by 65438 0℃; New greenhouse gas emissions will lead to an additional 2-6℃ increase in the global average temperature. These two factors will also cause the sea level to rise by10cm and 25cm respectively every century. To curb the trend of climate warming, global greenhouse gas emissions must be controlled at a very low level. Even so, the rising trend of sea level is inevitable, and the rising speed of 10 cm per century may be the most optimistic prediction.

The second paper published by Gerald Meyer and others predicted that even if no greenhouse gases were released into the atmosphere in this century, by 2 100, the global average temperature would rise by at least 0.5℃, and the sea level would rise by more than 1 1 cm, in which the speed of sea level rise was more than twice that predicted by scientists earlier. Mel explained that this is because the previous forecast did not take into account the impact of glacier melting.

Mel's research team used two sets of mathematical models and supercomputers to simulate the climate and sea level changes at low, medium and high global greenhouse gas emissions.

The latest research by scientists in China shows that the reduction of vegetation coverage on the earth's surface has an inevitable internal relationship with global warming. Firstly, this more scientific mathematical model is briefly introduced.

First of all, we must introduce some simple physical knowledge:

First of all, mechanics

Joule's law

British physicist Joule did many experiments. In 1840, he first accurately determined that the heat generated by a current passing through a conductor is proportional to the square of the current, to the resistance of the conductor, and to the electrifying time. This law is called Joule's Law. Joule's law can be expressed by the formula Q = I 2RT.

Third, photoelectric effect.

When light shines on some substances, the electrical properties of the substances change, that is, light energy is converted into electrical energy. This photoelectric change phenomenon is collectively called photoelectric effect. The photoelectric effect can be divided into photoelectron emission, photoconductive effect and photovoltaic effect. The former phenomenon occurs on the surface of an object, which is also called external photoelectric effect. The latter two phenomena occur inside the object, which is called internal photoelectric effect. Hertz discovered the photoelectric effect in 1887, and Einstein was the first to explain it successfully.

Fourth, the tip discharge effect

faraday law of electromagnetic induction

The concept of field distribution of intransitive verbs

In a word, it is actually the four mechanics of force, heat, light and electricity, some theories of modern physics, some knowledge of advanced mathematics and plate movement.

With this knowledge, you can understand the following words.

(1) major premise

The earth revolves around the sun and rotates at the same time. Huang Chi Angle is 23 degrees and 26 minutes. Under the irradiation of solar radiation, due to the photoelectric effect, the electrons on the surface objects are constantly ionized, and the negative ions formed rise with the hot air, making the surface positively charged. The charging amount is linearly related to the intensity and time of solar radiation. In other words, the sun is constantly charging the surface with positive charges, while negative charges rise to the sky. The whole surface and atmosphere constitute a super-huge capacitor.

(2) How will the charge be distributed on the surface?

Because seawater is a good conductor, in contrast, the continental plate is a bad conductor, so the charge can flow quickly at sea level, but relatively slowly on the mainland. Due to the tip effect, charges will continue to accumulate in higher altitude areas on the earth's surface. Therefore, the total current effect at sea level is zero, and the current effect will mainly be reflected in the continental plate. In this way, the current and charge model of the earth can be established and the distribution can be calculated according to the basic parameters such as the distribution of the earth's plates, the detailed topography of the surface, the rotation of the earth and the angle of solar radiation. Theoretically, the results are very consistent with the actual situation, which depends on the accuracy of parameter selection and the data processing ability of the computer.

(3) Current field distribution and geomagnetic field mechanism.

When one side of the earth is facing the sun, according to this theoretical model, if the external solar radiation is completely shielded, the charge movement trend on the earth's surface is constantly moving to the tip, resulting in a current field of 1, which is called a magnetic field of 1 (this current field is related to the distribution of the surface and the altitude of the land, and the current is isotropic, so its overall effect is zero, but it can affect the geomagnetic field distribution in local areas); At the same time, the earth's surface is constantly discharging, so in the case of solar radiation, the charge distribution on the side facing the sun (mainly distributed in the mainland) is the most in the east and the least in the west (because the earth rotates from west to east), so the current from east to west is formed on the side facing the sun, which is called current distribution 2, and this current generates a magnetic field, which is called magnetic field 2. It can be seen that the magnetic field on the side facing away from the sun is stronger, and the magnetic field on the side facing away from the sun is opposite. In addition, with the rotation of the earth, the magnitude of the magnetic field generated by the positive charges accumulated at the surface tip can be called magnetic field 3; The negative charge on the earth's surface also produces a current field 4 with the rotation of the earth, which corresponds to a magnetic field, which can be called a magnetic field 4. Because the total amount of positive and negative charges is equal, the total effect of magnetic field 3 and magnetic field 4 is zero. To sum up, magnetic field 2 is the main source of geomagnetic field, and the specific data need to be modeled and calculated according to detailed data such as solar radiation and continental plate distribution.

(4) How does the Earth achieve charge balance?

The earth can be regarded as a super capacitor. When the sun continuously charges the supercapacitor at 65,438+0,800a, it also discharges at 65,438+0,800a (see Feynman Physics Lecture, the average lightning current is 65,438+0,800a, and it can be inferred that the charging current is 65,438+0,800a). This kind of discharge is lightning, so today on earth, lightning needs to break through the air, so it often happens in areas with high air humidity, such as rainy and windy weather and high-altitude crater areas. The electric field intensity on the earth's surface is greater than 100V/m from bottom to top (see Feynman's lectures on physics), and the electric field distribution should be from the surface to the ionosphere. So it can be inferred that the earth's supercapacitor contains a lot of energy. Since there is a lot of charge, why can't we feel it? Because we are at the same potential and dry air is an excellent insulator, we have no feeling.

5] What will happen if the surface vegetation decreases?

As can be seen from the above points, the earth's large capacitance is a balanced system. For a long time, the ecological environment and vegetation coverage on the earth are relatively stable, so the water content of the surface is also relatively stable, so the conductivity of the surface is also relatively stable. According to this theory, when the surface vegetation decreases, the surface conductivity decreases, that is, the resistance increases, that is, the internal resistance of the earth capacitor increases, while the charging power, that is, solar radiation, is relatively stable. According to Joule's law, this increases the heat value of the earth's surface to some extent and promotes global warming to some extent.

[6] What will happen if the surface vegetation disappears in large quantities or there is a large area of drought?

For example, thousands of kilometers of vegetation in Fiona Fang have disappeared or become dry, resulting in a large area of the surface becoming an insulator, unable to flow according to the original current field, and a large amount of charges are accumulated on the surface. Because of the coulomb force between charges, it is intuitively manifested as the formation of cracks on the land surface, macroscopically as the tension of the continental plate where it is located, and the energy form is elastic potential energy. The longer the drought, the greater the energy accumulation. When the humid air moved to this area, the earth became a good conductor again because of the rain, and a large amount of charges accumulated on the surface quickly moved to the tip, so it rained cats and dogs, accompanied by a lot of lightning, and the energy was released quickly, which caused the abnormal movement of the continental plate. This energy release is insignificant to the earth, but extremely destructive to human beings.

From this model, we can know that the decrease of surface vegetation is one of the main driving forces of global climate anomaly. While the surface temperature is rising slowly, various abnormal weather phenomena are becoming more frequent and the interaction is complex, which requires more and more detailed data, such as atmosphere, ocean currents, geology and so on. This model can be used as the basic model of geophysics. The concrete analysis of specific problems can also be extended to other celestial bodies and galaxies.

The extensive use of fossil energy, on the one hand, causes greenhouse gas emissions, on the other hand, a large number of acid rain reduces vegetation and makes the climate abnormal.

Ocean change

Talking about climate change and sea level rise is very compelling news. In fact, the sea is not a plane, and the sea level in different parts of the ocean is different. The sea level varies greatly between different oceans. What human beings care about and observe is actually the sea level along the coast. There are many factors that affect the change of coastal sea level, such as tides, weather, such as climate change, and the rise and fall of land itself. Of course, different factors have different time scales.

Human beings have observed the changes of coastal sea level for a long time, but the representativeness of early data is generally insufficient. The data in the Mediterranean is better. According to observation, the sea level in the Mediterranean Sea did not change more than plus or minus 25 cm during the long period from 1 century to 1900, or it was basically stable. During this period, the change rate of sea level rise and fall in the Mediterranean is basically between 0 and 2 mm per year. After entering modern times, tide gauges were installed on all ocean surfaces in the world in the second half of the19th century, so there were monitoring data of all ocean surface heights. These historical data can find an obvious trend of accelerated sea level rise, but the data is not enough for quantitative analysis. The data recorded by a comprehensive and systematic tide gauge started from 196 1, and it was observed that the average speed of global sea level rise from 196 1 to 2003 was 1.8+-0.5 mm per year, during which the sea level did not simply rise, but some. More comprehensive sea level data began with the satellite survey of 1993. In theory, satellite observation can obtain the most direct sea level observation data. Satellites observed that from 1993 to 2003, the global sea level rose at a rate of 3.1+-0.7mm per year, which was obviously faster than before. But whether this acceleration is a short-term change or a long-term trend is not easy to draw a conclusion. According to the records of tide gauge station, the rising speed of sea level from 1993 to 2003 occurred after 1950, which is not unique.

Like many climate problems, although the global sea level is generally on the rise, the sea level changes in different oceans are different. According to observation, since 1992, the biggest sea level rise has occurred in the western Pacific Ocean and the eastern Indian Ocean. The sea level of the whole Atlantic is basically rising except for parts of the North Atlantic, but actually it is falling in parts of the East Pacific and the West Indian Ocean. Those who are interested can pay attention to the position where several small island countries have made such a terrible noise, and see if the problem really exists and whether it is really urgent for them. Different island countries, the situation is still very different.

cause analysis

human factor

1. Population explosion factor

The rapid growth of population is one of the main factors leading to global warming. At the same time, it also seriously threatens the balance between the natural ecological environment. With such a huge population, the amount of carbon dioxide emitted by itself every year will be an amazing number, and the result will directly lead to the continuous increase of carbon dioxide content in the atmosphere, thus directly affecting the climate change on the earth's surface.

2. Atmospheric environmental pollution factors

The increasingly serious environmental pollution has become a major global problem, and it is also one of the main factors leading to global warming. The research on global climate change in 2 1 century has clearly pointed out that the temperature of the earth's surface has been rising since the end of last century.

3. Deteriorating factors of marine ecological environment

The change of sea level is on the rise. According to the prediction of relevant experts, the sea level may rise by 50 cm by the middle of the next century. If no measures are taken, it will directly lead to the destruction and pollution of fresh water resources and other adverse consequences. In addition, a large number of toxic chemical wastes and solid wastes produced by land activities are continuously discharged into the sea; Major oil spills in seawater and the destruction of coastal ecological environment by human activities are the main factors leading to the destruction of seawater ecological environment.

4. Land destruction factors

The main cause of soil erosion and desertification is improper agricultural production. As we all know, good vegetation can prevent soil erosion. However, by the current year of 20 14, due to excessive deforestation, land reclamation for agricultural production and overgrazing, human activities are still seriously destroying vegetation. Land desertification, soil erosion of 47 thousand tons. Soil erosion reduces soil fertility and water retention, thus reducing soil biological productivity and its ability to maintain productivity; It may also lead to large-scale floods and sandstorms, causing huge economic losses to society and deteriorating the ecological environment.

5. Factors of sharp decline of forest resources

Worldwide, due to natural or man-made factors, the forest area is decreasing sharply.

6. Hazard factors of acid rain

The influence of acid rain on ecological environment has attracted more and more attention all over the world. Acid rain will destroy forests, acidify lakes and endanger living things. In the 20th century, acid rain around the world was mostly concentrated in Europe and North America, and most of them occurred in developed countries. In some developing countries, acid rain also occurred and developed rapidly.

7. Factors accelerating species extinction

Life on the earth is a precious resource for human beings, and the diversity of life is the basis for human survival and development. But the biological species on the earth are disappearing at an unprecedented rate.

8. Water pollution factors

According to the water quality monitoring project of Global Environmental Monitoring System, about 65,438+00% of the monitored rivers in the world are polluted. Since the beginning of this century, the water consumption of human beings is increasing rapidly, and the scale of water pollution is also expanding, forming a contradiction between supply and demand of fresh water. Therefore, the treatment of water pollution will be very urgent and important.

9. Toxic waste pollution factors

More and more toxic chemicals not only pose a serious threat to human survival, but also do harm to the ecological environment on the earth's surface.

natural cause

1. Volcanic activity

2. Periodic orbital changes of the earth.

The earth's periodic orbit changes from ellipse to circle, which is closer to the sun. According to a scientist's research, the temperature of the earth has been alternating between high temperature and low temperature, with certain regularity.