The Regional Impacts of Climate Change

Other reports in this collection Agriculture

Three subregions in north China appear to be especially sensitive to climate change because of potential increases in the soil moisture deficit:

  • Areas along the Great Wall-This area lies southeast of the transition belt between agriculture and animal husbandry. Warming and increased evapotranspiration, along with possible declines in precipitation, would make it difficult to maintain current crop patterns. The northern rangeland would gradually intrude into this area, creating a transition zone dominated by livestock. The northWestern part of this area would become an arid grassland.
  • The Huang-Hai plains-Climatic warming may increase the moisture deficit (i.e., the difference between precipitation and evapotranspiration) by more than 70 mm and result in more frequent and severe spring droughts with hot, dry winds, damaging wheat production and limiting the present practice of double-cropping in succession. Dryland crops will suffer from drought.
  • The area north of the Huaihe River, including eastern Shandong-This area lies along the southern edge of the temperate crop zone. Climate warming may cause the northward shift of subtropical crop areas. However, projected frequent waterlogging in the south and spring droughts in the north would inhibit the growth of subtropical crops.

The state and farmers can take steps to adapt agricultural production to the unfavorable impacts of possible climate change. Such strategies include allowing the sown acreage of grain to stabilize at a level of 0.8-0.9 ha per capita to attain the production target; strengthening irrigation capacity as one of the most beneficial means of maintaining agricultural production in the face of unfavorable climate change; and transforming medium- or low-yield farmland into high-yield farmland. To maintain the productivity of cultivated land, it is necessary to popularize a more optimal fertilizer mix and adopt the technique of subsoil application according to actual changes in soil conditions. It also is necessary to use and extend technology for agricultural adaptability-such as using superior species of crops, improving standardized cultural techniques under climatic variation, using dryland farming techniques, and developing feed crops instead of grain crops. Forests

Forests in northern China have been seriously depleted over the past few centuries. Despite recent reforestation efforts, the forested area in the region is only 11.8% of the total land cover, which is lower than the mean value for China. Under the influence of projected climate change, the distribution pattern of many important tree species would be affected. For example, the present forests of Pinus tabulaeformis, a key temperate species widely distributed in northern China, will be reduced an additional 9.4% under a 2xCO2 equilibrium climate (Guo, 1995). Coastal Zones

For the southern coast of Shangdong, estimated sea-level rise by the years 2030, 2050, and 2100 would be 1.1, 5.7, and 40.2 cm, respectively and, for the coast of Liaoning-Tianjin, 13.1, 22.5, and 69.0 cm, respectively (Du et al., 1996). Construction of dikes and seawalls is likely to be the most common adaptation strategy in these areas; this practice has been used there throughout history to combat sea encroachment (ESD-CAS, 1994).

Box 10-2. Sea-Level Rise at Major Deltas of China (ESD-CAS, 1994)
The Old Huanghe (Yellow River) delta, the Changjiang (Yangtze River) delta, and the Zhujiang (Pearl River) delta are major areas of economic activity in China. The metropolises of Tianjin, Shanghai, and Guangzhou (Canton) are located within these three deltas, respectively. The three deltas are located in regions with tectonic subsidence rates of about 2-3 mm/yr, 1-2 mm/yr, and 1-2 mm/yr, respectively (although hilly lands in the Zhujiang delta have a tectonic uplifting rate of 1 mm/yr). The Old Huanghe delta and the Changjiang delta have experienced severe land subsidence problems in the past as a result of groundwater extraction. Recent efforts to mitigate this problem have been successful in reducing the subsidence rate. It is estimated that these rates can be controlled within the range of 6-10 mm/yr for the Old Huanghe delta and 3-5 mm/yr for the Changjiang delta. In the Zhujiang delta, natural progradation of the coast and active land reclamation activities have resulted in a 0.5-1 mm/yr sea-level rise in the distributaries in the estuarine area-the same order of magnitude as the projected value due to climate change. This rate is expected to continue for some time. In the next 50 years, therefore, the expected eustatic sea-level rise due to climate change will not be a major factor in relative sea-level rise for the Old Huanghe and Changjiang deltas, although it may be for the Zhujiang delta.


Integrated vulnerability to climate change for northern China, including the vulnerability of forests, is summarized in Table 10-10.

Table 10-10: Integrated vulnerability to climate change in northern China.

Sector Scenarios Method Most Vulnerable Region Summary of Results Cross-Sector Impact

Water Resources (W) LLNL (1)
Climatic, hydrological, and socioeconomic indices Hai-Luan River Basin, followed by the Huaihe River Basin Runoff change of -16 to +17% Decreased supply to (A) and reduction with (F)
Agriculture (A) GFDL-A3
CERES and other crop models; moisture deficit and socioeconomic indices Hebei, Shanxi, inner Mongolia, and along the Great Wall Yield change of wheat (-6 to +42%), maize (-9 to +5%), rice (-21 to -7%), cotton (+21 to +53%) Increased risk for (F) and increased demand for (W)
Forests (F) LLNL (1)
Aridity and fuelwood supply indices All areas Productivity increase of +1 to 10%; area change of -57 to +12% (varying with species) Increased risk from (A) and effect on (W)
Coast Zone (CZ) Sea-level rise of 30-65 cm IPCC 7-step method Jing-Jin-Tang and Yellow River Delta Likely and viable strategy of dike sand seawalls Increased risk to (A) and (W)

(1)L. Gates, pers. comm.

Source: Lin et al., 1994.


Other reports in this collection

IPCC Homepage