Global climate change has experienced Medieval Warm Period, Little Ice Age and Modern Warm Period for last thousand years. In current hundred years, climate change in China has obvious regional features in contrast with global background. The highest temperature appeared in 1940s instead of 1980s. The warming trend is notable in northern parts of China and 13 warming winters have successively happened in those areas. Southern and southwestern parts of China are likely becoming colder. Climate disasters have been tending to aggravate in the whole country since 1990s and become an obstacle to sustainable development. As to climate change in future, although there would be some regional difference, the warming tendency seems clear, which has comprehensive and significant impacts on socioeconomic development. It is particularly urged to enhance environment protection, improve climate monitoring and predicting, and work out adapting and mitigating strategies to deal with climate change.

Global climate fluctuated in last thousand years. Chinese scientists divide it into three phases, i.e., Medieval Warm Period, Little Ice Age and Modern Warm Period^[1]. During 900-1300 AD, global climate was in Medieval Warm Period. Temperature anomaly during 1000-1200 AD was positive, while during 1200-1300 AD negative, the lowest temperature appeared around 1350 AD. It is accepted that Medieval Warm Period finished at the end of 14^th century. After that, temperature fluctuated for two centuries, and then Little Ice Age began^[2]. It lasted for three centuries and ended around 1850 AD. Modern Warm Period started at the beginning of this century, lasted for the whole century, and will most likely sustain for next century. Similar to temperature fluctuation in that period, precipitation distribution changed remarkably. In last 2000 years, precipitation in China was tending to decrease and climate became dry especially during 280-490 AD^[3].

In recent hundred years, due to natural variability and anthropogenic activities which caused more emission of green house gases, global warming was distinct. According to the second assessment report of the Intergovernmental Panel on Climate Change (IPCC) ^[4], global mean surface air temperature has increased by between about 0.3-0.6º since the late 19^th century. Recent years have been among the warmest since 1860s, i.e., in the period of instrumental record. By using coupled atmosphere and ocean dynamic models, IPCC predicts that global mean surface air temperature will increase by between about 1.0-3.5º in next century, which in turn will increase global water cycle rate, change precipitation distribution and cause more droughts and floods.

Although the trend of temperature change in China was similar to the one in the world, the warmest decade in China appeared to be in 1940s instead of 1980s. Temperature in northern parts of China has rapidly increased since 1950s. Among the area, temperature in northeast China, Inner Mongolia and Xinjiang autonomous regions rose as high as 1.0-2.5º. Temperature elevated more rapidly in winter than in summer. It is recorded that there are 13 successive warm winter in northern area. In contrast with the situation in northern area, a cooling trend has been observed in South China and Southwest China since 1950s, which is also different with global warming^[5]. It is further found that temperature changed with seasonal difference. The first maximum value of temperature increase in winter appeared in 1940s, while the one in summer appeared in 1930s. Furthermore, of the two the former is higher than the latter. In recent 40-50 years, temperature rose with a rate of 0.30º/10 years in winter while 0.23º/10 years in summer^[6]. Precipitation also changed strikingly in recent 40 years. Precipitation was relatively abundant in most part of the country during 1950s, while decreased obviously after 1960s. Besides slight increase in northern part of Northeastern China and part area of Xinjiang Uigur Autonomous Regions and Tibetan Plateau, precipitation has decreased in most part of China, especially in North China, since then.

Based on the background of climate change and variability, meteorological disaster seemed to become more severe after 1990s. Extreme weather events such as drought, flood, typhoon, high temperature, cool injury, early frost and blizzard happened frequently and intensely. The heavy deluges happened in recent years especially in 1991 and 1998 in the Yangtze River are the typical examples. All the facts show that the atmospheric environment on which human being rely for existence and development has significantly changed. We should attach great importance to climate change when implementing sustainable development policy.

Global climate change has decisive influence over socioeconomic development and ecotope protection. Furthermore, in step with rapid economic development, the intensity of influence is getting higher and higher. With broad territory, complicated topography, wide scale of longitudes, variable monsoon system, different climate type in different regions and heavy meteorological disasters, China is in one of the global climate’s vulnerable regions. In the long history, climate change and meteorological disasters frequently caused calamity to Chinese people and impeded the advance of society. In recent years, on one hand, with the enhancement of disaster preparation, the damage degree was declining. On the other hand, with the rapid economic development, the amount of economic damage was rising. According to statistics, mean annual direct economic damage is close to 200 billion Yuan. In 1996, 1997 and 1998, the values are as high as 288.2, 197.5 and 300.7 billion Yuan, respectively.

According to climate predictions provided by Chinese scientists, global warming will continue in next century, but the warming scope in China will be greater than global mean value^[8] and the uncertainty of precipitation will increase. The significant impacts of climate change on Chinese sustainable development are as follows:

1. Impacts on agriculture There will be different influences on different crops in different regions. As to the whole country, the yield of 7 main crops will decrease about 4.4 percent in 2030, if other crops are included, the yield will decline more than 5 percent. According to the prediction outputs of several models, the amount of stockbreeding will reduce about 6 percent.

2. Impacts on fishery The fishing yield will increase 28 percent because the increase of CO₂ concentration will result in greater biomass in the water. On the contrary, the yield will reduce 4 percent due to the warming temperature and the changing precipitation. Moreover, the yield will reduce 28 percent as a result of the more frequent climate disasters such as typhoon and flood. Totally, the yield will decrease over 5 percent in virtue of climate change.

3. Impacts on forest Forests are highly sensitive to climate change. The productivity will increase 1-2 percent in tropical and subtropical forests, 2 percent in warm temperate forests, 5-6 percent in temperate forests and 10 percent in boreal forests. But the plant area of main species will become smaller.

4. Impacts on hydrology and water resources The outputs of 4 GCM indicate that climate change will cause either the runoff in all main rivers in the whole country declined or the runoff to the south of Huai River increased and to the north of Huai River decreased. Water shortage in Yellow River, Huai River ane Hai River will appear in spring, fall and especially in summer. It is estimated that water shortage for Beijing, Tianjin and Tangshan will reach 0.15-1.4 billion m, for Yellow River basin 2.1-13 billion m in 2030.

5. Impacts on sea level The available estimates of sea level under a changing climate will possibly rise 10-12 cm in Bohai Sea and 13-14 cm in Yellow Sea and East China Sea, which will potentially impact on the delta areas in the Yangtze and Pearl Rivers.

6. Impacts on energy demand Forced by a doubled CO₂ climate, global electricity demand will increase 353.9´ 10TWH under a possible 2ºC increase of temperature. China will increase 17.1´ 10TWH, as 48 percent of the total global increase.

7. Impacts on ecological environment The warming climate will result in temperature zones moving northward, which will in turn cause species and distribution of vegetation and soil changes. The frozen soil frontier in Northeast China will retreat to 52N, while most part of plateau soil in West China will melt. Because of increasing evaportranspiration, soil humidity will decrease 2.4 to 2.9 percent in 50 years. The droughts in northern arid and semi-arid regions will develop in certain degree, and desertification will be more severe.

8. Impacts on disastrous weather Climate warming will result in more disastrous weather events. Tropical cyclone and typhoon will frequently and intensely happen. Floods will increase 40-50 percent.

Although there are many uncertainties about climate change and its impacts, and what mentioned above are merely tentative analysis from scientists, it is no denying that climate change in future do have significant influence on sustainable development in China. All of us must heighten our vigilance to the situation.

Since climate change has discernible impacts on sustainable development in China, it is urgent to take active and effective measures to adapt and mitigate climate change. Some policy and strategy suggestions are put out as follows:

1. To improve energy structure, raise energy efficiency and reduce green house gases (GHGs) emission. The concentration of GHGs, such as CO₂ and so on, is main cause for global warming. Therefore, in order to mitigate climate change, GHG emission must be reduced. In terms of the UN Framework Convention on Climate Change, the developing countries, including China, do not assume the responsibility for reducing GHG emission. In spite of that, we should still give our contribution to global environmental protection. We should adjust energy structure and distribution, taking coal as basis, electric power as center, developing hydroelectric power, oil and natural gas, exploiting renewable energy, and appropriately gnowing nuclear energy. We ought to raise energy effluence, put energy resources to rational use, reduce GHG emission and control environmental pollution based on scientific and technologic progress.

2. To expand and protect forest, and enhance the CO₂ Sink. Forest is main part of terrestrial ecological system and has critical function to ecologic and environmental protection. It is the most effective way of absorbing and solidifying CO₂ to plant more trees everywhere, control excessive lumbering, increase biomass. We should take more measures to protect forest and diminish lumber consumption.

3. To continuously carry out family control policy, and mitigate population growth. Chinese population now has exceeded 1.2 billion and is still growing with a rate of 15 million per year. The stress on resources and environment exerted by population expansion, has become first urgent issuer to Chinese socioeconomic development in coordination will environmental protection. It is crucial to control population and develop sustainable consuming pattern for climate mitigation.

4. To formulate compensation regulations for using natural resources. In China, fresh water, arable land, forest and grass land are not rich, per capita amount only takes 28.1, 32.3, 14.3 and 32.3 percent of global mean level, respectively. Mineral resources is also inadequate, per capita amount is less than half-global mean value. Furthermore, unreasonable use and waste of resources aggravates insufficiency of resources. When we develop socialist marketing system, we must formulate economic regulations, reform unreasonable price system to use resources in a sustainable way and mitigate climate changes from its source.

5. To enhance climate monitoring and predicting in order to diminish its impacts. To monitor climate is a good way to understand its changing law, while to predict its changing trend is a useful way to prepare, adapt and mitigate its impacts and diminish economic loss caused by meteorological disasters. We should now construct our atmospheric monitoring system; develop regional dynamic climate models and integrated climate assessment modes to improve climate monitoring, predicting and assessing ability.

6. To improve environmental law and regulation system and enhance public education on sustainable development. Though environmental protecting system has been initially developed in recent years, it should still be improved to ensure implementation of the principle that economic development must be coordinated with environmental protection. We ought to develop the public education to further wake social consciousness on environment and climate protection, and finally reduce GHG emission and keep ecological system in a reasonable cycle.

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