The fourth assessment report of the Intergovernmental Panel on Climate Change (IPCC) shows that during the period from1906 to 2005, the global average surface temperature increased significantly, with a linear upward trend of 0.74℃. Considering the data error, the increase range is between 0.56℃ and 0.92℃. Among them,10 ~ 40s and 70 ~ 2 1 decade were two obvious warming stages, and the warming trend in recent 30 years was particularly strong.

In the past 100 years, the average temperature in Chinese mainland has also increased significantly, with an annual average temperature increase of about 0.8℃, with the most obvious warming in winter and little change in summer. During the period from 195 1 to 2004 in China, the annual average surface temperature warming range was about 1.3℃, which was much higher than the global average warming range in the same period, and was also far stronger than the average warming trend in recent 100 years, especially in the northeast, north China, northwest China and northern Qinghai-Tibet Plateau. It is worth noting that rapid urbanization and its enhanced urban heat island effect have obvious effects on climate warming recorded by most ground stations in China. In North China, where the warming is obvious, the annual average temperature increase near the national station 196 1 to 2000 caused by urbanization accounts for more than 39% of the total warming. In the trend of warming in other parts of China, the influence of the strengthening factors of urban heat island effect has been more or less retained. Since the early 1960s, the temperature change trend in the middle and lower troposphere in China is not obvious, only 0.05℃ per 10 year, which is one order of magnitude smaller than the temperature change observed by the national ground station. The annual average temperature in the upper troposphere and the lower stratosphere shows a significant downward trend. This also shows from another angle that the warming recorded by ground stations in China reflects the influence of urban development and urban heat island effect to a certain extent.

Of course, even excluding the influence of urbanization, the surface temperature in China has obviously warmed in the last half century, which is consistent with the reported global climate change. However, after considering the influence of urbanization, the average land warming rate in China and the world may be weaker than that reported at present. This judgment is very important for climate change research.

At present, people are concerned about climate change, which is a global warming phenomenon on the scale of decades to centuries. To understand the background and causes of climate change, it is necessary to have a long enough observation data series covering the whole world. However, most of the weather stations on land in the world have records of less than 100 years, which is difficult to meet the needs of scientific research. In this case, climatologists use surrogate data to restore the evolution process of surface climate elements in the past for a longer period of time. Commonly used temperature proxy data include tree ring width and density, historical documents, oxygen isotopes in ice cores, chemical compositions of corals and stalagmites, etc.

Research by scientists in China shows that the warming of the northern part of the Qinghai-Tibet Plateau in the past 65,438+000 years may be unprecedented in the past 65,438+0000 years. However, the reconstruction of the winter average temperature in eastern China and the national annual average temperature shows that the climate warming in China in the 20th century did not significantly exceed the "medieval warm period". During the period from1000 to1310, China showed a warm stage corresponding to the "medieval warm period" in the northern hemisphere, especially in eastern China. The "Little Ice Age" from14th century to19th century is also clearly reflected in the national average temperature series. /kloc-From the middle of the 9th century to the 1980s, the surface temperature in China increased significantly, but the modern temperature increase in the 1980s did not exceed the level of "medieval warm period".

Therefore, the existing long-term paleoclimate sequence does not show that the modern warming of the northern hemisphere land and China is very abnormal. Some scientists believe that in the past 1000 years or longer, solar activity, volcanic activity and low-frequency vibration in the climate system may have an important impact on climate change. Obviously, from the perspective of paleoclimatology, it is not certain that the climate change in the 20th century was mainly caused by human activities.

2. Injuries and consequences

1, climate warming, melting glaciers and rising sea level will cause the loss of coastal beaches, mangroves, coral reefs and other ecological groups, global warming coastal erosion, seawater intrusion into coastal groundwater layers, coastal land salinization and other terrible consequences. , resulting in the imbalance of natural ecological environment in coastal areas, estuaries and bays, and bringing disasters to coastal ecological environment systems. 2. The water area has increased. Water evaporation is also more, the rainy season is prolonged, and floods are more frequent. The chances of being flooded increase, the degree and severity of being affected by heavy rain increase, and the life of reservoir dams is shortened. The rising water temperature may melt the ice and snow in Antarctic Peninsula and Arctic Ocean. Polar bears and walruses will be extinct. 4. Many small islands will disappear without a trace and will be infected with infectious diseases such as malaria ... 5. Due to thermal inertia, the existing greenhouse gases will continue to affect our lives. 6. The increase of temperature will affect people's fertility, and the activity of sperm will decrease with the increase of temperature.

3. the reason

cause

1, population explosion factor The population explosion in recent years is one of the main factors leading to climate warming. At the same time, it also seriously threatens the balance between the natural ecological environment. With such a huge population, the annual carbon dioxide emitted by itself 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 At present, the increasingly serious environmental pollution has constituted a major global problem, and it is also one of the main factors leading to climate warming. Now, the research on climate change has clearly pointed out that the temperature of the earth's surface has started to rise since the end of last century. 3. Deteriorating factors of marine ecological environment At present, sea level changes are 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. Destructive factors such as land erosion and desertification 5. The world's forest resources have been drastically reduced, and the forest area has been greatly reduced due to natural or human factors. 6. The harm of acid rain The impact of acid rain on the ecological environment has attracted more and more attention all over the world. Acid rain will destroy forests, acidify lakes and endanger living things. At present, most of the acid rain in the world is concentrated in Europe and North America, and most of them occur in developed countries and some developing countries. Acid rain is also occurring and developing rapidly. 7. Factors that accelerate the extinction of species 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 at present, the biological species on the earth are disappearing at an unprecedented rate. 8. Water pollution factors According to the water quality monitoring project of the 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 chemicals with increasing toxic waste pollution factors not only pose a serious threat to human survival, but also bring harm to the ecological environment on the earth's surface. 10, the change of the earth's periodic orbit, the earth's periodic orbit changes from oval to round, closer to the sun. According to a scientist's research, the temperature of the earth changes alternately between high temperature and low temperature, which has certain regularity.