Global climate change problem

Annual increase of concentration in gas atmosphere (ppm(%) Life span (year) Greenhouse effect (CO2 = 1) Main source of existing contribution rate (%)

Coal, oil, natural gas and deforestation

CFC 0.00085 2.250-1023400-1500024 Foaming agent, aerosol, refrigerant and cleaning agent.

Methane1.7140.812-17115 wetlands, paddy fields, fossils, fuels and livestock.

Fossil fuels, fertilizers and deforestation

Quoted from Global Environment Facility: Attaching Importance to Global Environment, 1998.

Some scientific observations since this century show that the concentration of various greenhouse gases in the atmosphere is increasing. Before 1750, the carbon dioxide content in the atmosphere was basically maintained at 280ppm. After the industrial revolution, with the continuous growth of human activities, especially the consumption of fossil fuels (coal, oil, etc.). ) and the massive destruction of forest vegetation, greenhouse gases such as carbon dioxide emitted by human beings are increasing, and the content of carbon dioxide in the atmosphere is gradually increasing, rising by about 1.8 ppm (about 0.4%) every year, and has risen to nearly 360ppm so far. According to the measurement results, the increase of carbon dioxide in the atmosphere is about half of the man-made emission. According to the assessment of the Intergovernmental Panel on Climate Change (IPCC), in the past century, the global average surface temperature rose by 0.3℃ to 0.6℃, and the global sea level rose by 10 to 25 cm. Many scholars predict that by the middle of the next century, if the world energy consumption pattern does not change fundamentally, the concentration of carbon dioxide in the atmosphere will reach 560ppm, and the average temperature of the earth will rise sharply. The Intergovernmental Panel on Climate Change issued a new assessment report in 1996, which once again affirmed that the increase of greenhouse gases will lead to global climate change. According to various computer models, if the concentration of carbon dioxide rises from 280ppm before the industrial revolution to 560ppm, the global average temperature may rise by 1.5℃ to 4℃.

Figure 1 Changes of atmospheric carbon dioxide concentration and temperature

Second, the factors affecting climate change.

Nature itself emits all kinds of greenhouse gases, but it also absorbs or decomposes them. In the long-term evolution of the earth, the changes of greenhouse gases in the atmosphere are very slow and circular. Carbon cycle is a very important natural cycle process of chemical elements. Atmospheric and terrestrial vegetation, atmospheric and marine surface plants and plankton exchange a large amount of carbon every year. From the perspective of natural forests, the absorption and emission of carbon dioxide are basically balanced. Human activities have greatly changed the land use pattern, especially after the industrial revolution, a large number of forest vegetation has been cut down rapidly, the use of fossil fuels has also increased at an alarming rate, and man-made greenhouse gas emissions have also increased accordingly. Globally, from 1975 to 1995, the energy output increased by 50%, and the carbon dioxide emissions increased significantly accordingly (see Figure 2-2). So far, developed countries have consumed most of the fossil fuels produced in the world, and their cumulative carbon dioxide emissions have reached an alarming level. For example, by the early 1990s, the cumulative emissions of the United States reached nearly 654.38+07 billion tons, the European Union reached nearly 654.38+02 billion tons, and the former Soviet Union reached nearly 654.38+065.38+00 billion tons. At present, developed countries are still the main emitters of greenhouse gases such as carbon dioxide, and the United States is the largest emitter in the world. The total emissions of some developing countries, including China, are also growing rapidly. After the disintegration of the former Soviet Union, China's emissions ranked second in the world, which became a concern of developed countries. However, in terms of per capita emissions and cumulative emissions, developing countries are still far below developed countries (see table 3).

Figure 2 1950- 1995 Global Carbon Emissions from Fossil Fuel Combustion.

Table 3 Carbon dioxide emissions (million tons) Per capita emissions (tons) of 15 countries with the largest carbon dioxide emissions

Usa 488 1 19.4438+03

2 China 2668 2.27

3 Russia 210314.11

4 Japan 1093 8.79

Germany 878 10.96

6 India

Ukraine 61111.72

8 UK 566 9.78

Canada 4 10 14.99

10 Italy

France 362 6.34

Poland 3428+0

Mexico 333.77

Kazakhstan 298 17.48

South Africa 290 7.29

All world resources: world resources) 1996-97-97.

The future trend of man-made greenhouse gas emissions mainly depends on the changing trend of population growth, economic growth, technological progress, energy efficiency improvement, energy conservation, relative prices of various energy sources and many other factors. Several internationally renowned energy agencies-International Energy Agency, US Department of Energy and World Energy Council-put forward various possible trends of man-made carbon dioxide emissions according to different scenarios of economic growth and energy demand. Judging from these scenarios and trends, in the case of moderate economic growth and no strong restrictions on the use of fossil fuels, fossil fuels will still account for about 3/4 of global commercial energy by 20 10, and their consumption may exceed 35% of the current level, and the carbon dioxide emissions related to energy use may increase by 30-40%. Energy consumption and carbon dioxide emissions in developing countries are growing relatively fast. By 20 10, it may increase from less than 1/3 of global carbon dioxide emissions in the early 1990s to nearly 1/2, in which China and India will account for about half of the emissions of developing countries. Even so, the per capita and cumulative emissions of developing countries are still lower than those of developed countries. By the middle of the next century, developed countries will still be the main responsible persons for the cumulative emission of carbon dioxide in the atmosphere. Of course, if countries around the world adopt economic and energy development strategies that are more suitable for environmental requirements, carbon dioxide emissions may have different prospects (see Table 2-4).

Table 4 Energy consumption and carbon dioxide emissions estimated by World Energy Council (1990-2020)

High-growth (1990-2020) Revised Reference Scheme (1990-2020) Reference Scheme (1990-2020) Strengthening Ecological Protection (1990-2020)

Annual economic growth rate (%)

OECD countries/former Soviet Union and Central European countries

developing country

Proportion of world energy demand growth (%)98-84 54 30

Ratio of annual carbon dioxide emission exceeding 1990 (%) 93 73 42 5

World resources institute, etc. : world resources) 1996-97-97.

Three. Impact and harm of climate change

In recent years, the hottest weather once in a hundred years has appeared in countries all over the world, and El Ni? o phenomenon has also occurred frequently, causing huge economic losses to all countries. Developing countries are weak in disaster resistance, and developed countries are not immune. 195 Chicago heat wave killed more than 500 people,193 a hurricane in the United States caused a loss of 40 billion dollars. In the 1980s, the insurance industry's climate-related claims amounted to $654.38+0.4 billion, almost reaching $50 billion between 654.38+0.990 and 654.38+0.995. These conditions show that the adaptability of human beings to meteorological disasters caused by climate change, especially climate warming, is quite weak, and actions need to be taken to prevent it. According to some current development trends, scientists predict the possible impacts and hazards as follows:

1. Sea level rise

About13 of the world's population lives within 60 kilometers of the coastline, with developed economy and dense cities. The expansion of marine water bodies and the melting of polar ice and snow caused by global warming may raise the sea level by 50 cm in 2 100, endangering the global coastal areas, especially the densely populated and economically developed areas. These areas may be submerged or invaded by seawater, beaches and coasts will be eroded, land will be degraded, seawater intrusion and floods will be intensified, ports will be damaged, coastal aquaculture will be affected, and water supply and drainage systems will be destroyed.

2. Affect agriculture and natural ecosystems

With the increase of carbon dioxide concentration and climate warming, it may increase the photosynthesis of plants, prolong the growing season, and make some areas in the world more suitable for agricultural planting. However, the rapid changes in global temperature and rainfall patterns may also make agriculture and natural ecosystems in many parts of the world unable to adapt to this change or quickly adapt to it, which will have a huge destructive impact and cause extensive forest vegetation destruction and agricultural disasters.

3. Intensify meteorological disasters such as floods and droughts.

The increase of climate disasters caused by climate warming may be a more prominent problem. A slight increase in the global average temperature may bring frequent climate disasters-excessive rainfall, widespread drought and persistent high temperature, resulting in large-scale disaster losses. According to the historical data of climate change, some scientists speculate that climate warming may destroy the ocean circulation, trigger a new ice age, and cause terrible climate disasters in high latitudes.

4. Affect human health

Climate warming may increase the risk of disease and mortality, and increase infectious diseases. High temperature will increase the burden of human circulatory system, and heat wave will lead to an increase in mortality. Malaria and other infectious diseases spread by insects are closely related to temperature. With the increase of temperature, malaria, lymphatic filariasis, schistosomiasis, leishmaniasis, dengue fever and encephalitis may increase or recur in many countries. At high latitudes, the risk of the spread of these diseases may be greater.

5. Climate change and its impact on China.

According to some research results of Chinese and foreign experts, the warming trend in China will be stronger in winter than in summer. Rainfall will increase in warm areas and coastal areas in the north and west, and the frequency of floods in the Yangtze River and Yellow River basins will be higher. Typhoons and rainstorms in the southeast coastal areas will also be more frequent; In spring and early summer, drought in many areas is aggravated, dry and hot winds are frequent, and soil evaporation is increased. Agriculture is the most affected sector. Rising temperature will prolong the growth period and reduce frost, and the "fertilizer effect" of carbon dioxide will enhance photosynthesis and have a favorable impact on agriculture; However, the increase of soil evaporation, flood disaster and seawater erosion will also reduce agricultural production. The impact on grassland animal husbandry and fishery is generally unfavorable. The most serious impact of sea level rise is to increase the frequency and intensity of storm surges and typhoons, and seawater intrusion and coastal erosion will also cause huge economic and social losses.

The global climate system is very complex, and there are many factors affecting climate change, including solar radiation, atmospheric composition, ocean, land and human activities. There are still uncertainties in the scientific understanding of climate change trends, especially the climate change trends in different regions and their specific impacts and hazards, and it is still impossible to make a more accurate judgment. But from the perspective of risk assessment, most scientists assert that climate change is a huge environmental risk facing mankind.

Four. International actions and countermeasures to control climate change

In order to control greenhouse gas emissions and the harm of climate change, the United Nations Conference on Environment and Development adopted the Framework Convention on Climate Change in 1992, proposing that the annual greenhouse gas emissions of developed countries should not be controlled at the level of 1990 by the 1990s. From 65438 to 0997, the second Conference of the Parties was held in Kyoto, Japan, and the Kyoto Protocol was adopted, which stipulated six kinds of controlled greenhouse gases, clarified the greenhouse gas emission reduction ratio of developed countries, and allowed developed countries to take joint implementation actions. The greenhouse gas emissions of developing countries are not limited.

Judging from the current causes of greenhouse gases and the scientific and technological means mastered by human beings, the main way to control climate change and its impact is to formulate appropriate energy development strategies, gradually stabilize and reduce emissions, increase absorption, and take necessary measures to adapt to climate change.

The main ways to control greenhouse gas emissions are to change the energy structure, control the use of fossil fuels, and increase the proportion of nuclear energy and renewable energy; Improve the efficiency of power generation and other energy conversion sectors; Improve the energy efficiency of industrial production departments and reduce the energy consumption of unit products; Improve the efficiency of civil energy such as building heating; Improving energy efficiency in the transport sector; Reduce the damage to forest vegetation, control the methane emission from rice fields and landfills, and thus control and reduce the emission of greenhouse gases such as carbon dioxide.

The main ways to increase the absorption of greenhouse gases are afforestation and carbon fixation technology, in which carbon fixation technology refers to the separation and recovery of carbon dioxide from combustion gases, and then deep-sea and underground disposal, or fixation by chemical, physical and biological methods. The technical principle of carbon sequestration technology is clear, but whether it can become a practical technology is still unknown.

The measures to adapt to climate change are mainly to cultivate new crop varieties, adjust agricultural production structure, and plan and build projects to prevent coastal erosion.

Judging from the possible policy measures taken by governments, one is to implement direct control, including limiting the use of fossil fuels and greenhouse gas emissions, and limiting deforestation; Second, the application of economic means, including collecting pollution taxes and fees, implementing emission trading (including joint implementation between countries), providing subsidy funds and development assistance; The third is to encourage public participation, including providing information, education and training to the public.

From the perspective of available technologies in the future, there are mainly energy-saving technologies, bioenergy technologies and carbon dioxide fixation technologies. In the face of global climate change, developed countries regard the development of energy-saving and new energy technologies as the focus of energy strategy. By the 1990s, the U.S. Department of Energy took the development of high-efficiency energy technologies and the reduction of greenhouse gases as its central task, and devoted itself to the development of various advanced power generation technologies and other forward-looking energy technologies facing 2 1 century.