The Regional Impacts of Climate Change

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10.2.6.3. Pollution Hazards

Experiments by Hatakeyama et al. (1991) showed that the higher temperatures are, the faster ground-level ozone forms and the longer high concentrations of ozone last. Therefore, global warming would accelerate the photochemical reaction rates among chemical pollutants in the atmosphere, increasing oxidants in many urban areas. High levels of photochemical oxidants are associated with eye irritation, severe respiratory irritation, increased frequency of asthmatic attacks of susceptible persons, and decreased pulmonary functions (Ando, 1993).

10.3. Integrated Analysis of Potential Vulnerabilities and Impacts

10.3.1. North China

North China-including Beijing, Tianjin, the four provinces (Hebei, Henan, Shandong, Shanxi), parts of Anhui province, and parts of inner Mongolia-is an economic center of China. It also is a topographical and climatological entity. Its population is 371 million, and its area is 76.5 million ha, including 28.9 million ha of cultivated land. Because this region already is at risk from normal climate variability, it also is likely to be quite vulnerable to long-term secular shifts. The concept of regions at risk is used here to focus on four different managed ecosystems: water resources, agriculture, forests, and coastal zones.

10.3.1.1. Water Resources

Water resources in north China are sensitive and vulnerable to climate change because:

• Water resource availability in this area amounts to merely 500 m³ per capita-half the critical value of the United Nations (UN) standard (1,000 m³ per capita) for maintaining socioeconomic and environmental development.
• There already is a high level of water project development in this region. For example, in the Haihe basin, the ratio of water supply to total runoff has reached 0.87, but the ratio of water demand to total runoff already is 1.32. Because of the shortage of surface runoff for meeting water demand, depletion of groundwater resources is very serious.
• Depending on the different scenarios used for GCMs, changes in runoff could range between -16% and +7%; these shifts would occur mainly during the flood season. Such changes could unfavorably affect reservoir capability for storage and flood control. Although water shortages resulting from climate change are likely to be less important than those caused by population growth, economic development, and urbanization (for example, in the Hailuang River basin, water shortages resulting from climate change are projected to be about 6.9-9.5 billion m³, whereas shortages from other factors are projected to be 25.2-47.8 billion m³), the potential water deficiency due to climate change in moderately and extremely dry years may seriously exacerbate the current water shortage-and thus badly affect socioeconomic development in this region.

Trends of runoff for north China under four GCM scenarios are shown in Table 10-9. (At its lower reach, the Huanghe is elevated above its neighboring lands.) Both surface water and groundwater in north China seem to be quite sensitive to climatic variability, especially on the Huang-Hai plain, according to the model results. Under these scenarios, climate change will result in an additional shortfall of 0.15-1.4 billion m³ of water in the Jing-Jin-Tang subregion, which would cause economic losses of US$50-800 million (constant 1990 values) in a normal year and US$230-2,270 million in a very dry year.