[1. global warming]

In the last hundred years, the climate of the whole world and China is experiencing remarkable changes characterized by global warming, which has had and will continue to have a great impact on the ecosystem and social economy of the whole world and China. At present, global warming has become a major concern of governments and scientific circles all over the world, and it is also a major concern of our government and scientific circles.

Due to the existence of greenhouse gases such as carbon dioxide in the atmosphere, the average temperature of the earth is maintained at about 65438 05℃. However, with the advancement of global industrialization, the concentration of greenhouse gases has been increasing. For example, the concentration of carbon dioxide has now reached 368ppmv, the highest value since 420,000 years. The direct consequence of the increase of greenhouse gas concentration is that the global temperature continues to rise. The 20th century was the warmest 100 in the past 100. In the past 140 years, the global temperature rose by 0.4-0.8℃ (average 0.6℃), and all the warmest years of 13 occurred after 1983. In the past 50 years, the temperature in the urban areas of the Yangtze River Delta has also increased, especially since the mid-1980s. In the 1990s, the annual average temperature was 0.9℃ higher than that in the 1950s, especially in winter. In the 1990s, it was 1. 1℃.

Scientists use 365,438+0 global climate models to predict the global climate change in the next 65,438+000 years under six representative greenhouse gas emission scenarios. It is predicted that the global average surface temperature will rise by 100 in the future, which may be the fastest increase in the past 10,000 years. Considering the interaction between carbon dioxide (CO2) and aerosol, the climate change in China in the future 100 is predicted. The results show that the temperature will continue to rise, and the scope and intensity of future warming will increase.

Observations and studies have proved that the concentration of major atmospheric greenhouse gases has indeed changed on a global scale and continues to increase. Observation and theoretical research also prove that the main reason for the change of greenhouse gas concentration is human activities, and the influence of human activities on atmospheric greenhouse gas concentration is mainly manifested in two aspects; First, greenhouse gases are directly discharged into the atmosphere, such as carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) directly discharged into the atmosphere by burning fossil fuels and biomass, and carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and chlorofluorocarbons (CFCs) discharged into the atmosphere through industrial production processes. Second, human activities have changed the sources and sinks of greenhouse gases in the atmosphere. For example, deforestation directly reduces carbon dioxide sinks, agricultural activities change land use and increase the sources of atmospheric methane and nitrous oxide, and air pollution emissions reduce methane sinks.

Classical physics and radiation physics can accurately prove that if there is no greenhouse gas on the earth's surface, the global average surface temperature will be 33 degrees Celsius lower than the actually measured global average surface temperature. A correct and direct inference is that the increase of atmospheric greenhouse gas concentration will increase the global surface temperature, which is commonly called global warming. In order to accurately calculate the surface temperature rise caused by the increase of atmospheric greenhouse gas concentration, people have done a lot of research in the past 30 years, and the tool used is numerical simulation. Based on the results of the main models today, we can draw the following conclusions:

With the doubling of atmospheric carbon dioxide, the global average surface temperature will increase by 1.5-3.5 degrees in the balanced climate change. Considering the great role of the ocean, if human beings do not take any control measures, the global surface temperature change rate will be 0. 1-0.3 degrees/10 year in the next century. The experimental results of air-sea coupling model on greenhouse gas concentration gradient are consistent.

In recent years, people have begun to notice that the increase of atmospheric aerosols (mainly sulfuric acid aerosols) caused by human activities will reduce the surface temperature and partially offset the temperature effect caused by the increase of greenhouse gases. Considering the cooling effect of aerosol, the climate rate caused by human activities in the next century may only be 0.05-0.2 degrees/10 year.

As mentioned above, human activities have indeed caused an increase in the concentration of greenhouse gases on a global scale, and the increase in the concentration of greenhouse gases will indeed cause global warming. The question is how quickly the concentration of greenhouse gases will increase in the next few decades to 100, and the climate change caused by it. In other words, by the end of the next century, how much will the global average surface temperature rise? How do other climate variables (especially precipitation) change? Will the climate variability change significantly? Will extreme weather events increase? What is the regional distribution of climate change? To what extent does the increase of aerosol concentration offset the increase of greenhouse effect? Unfortunately, modern science cannot give exact answers to all the above questions. Even for the climate observed in the past 100 years, we are not sure whether it is the influence of the increase of carbon dioxide, let alone how much this influence accounts for. The scientific uncertainty about "global warming" is indeed huge and multifaceted.