Climate change is projected to have favorable impacts on agriculture in
the northern areas of Siberia and to cause a general northward shift of crop
zones. Grain production in southWestern Siberia is projected to fall by about
20% as a result of a more arid climate.
Projections for 2010 indicate that the need for industrial roundwood could
increase by 38% (southern Temperate Asia) to 96% (eastern Temperate Asia).
These requirements may result in serious shortages of boreal industrial roundwood,
placing further stress on boreal forests.
Along most of the continental coast, relative sea level (i.e., sea level
in relation to land) is an important factor for coastal environments. Deltaic
coasts in China face severe problems from relative sea-level rise as a result
of tectonically and anthropogenically induced land subsidence. In the next
50 years, the expected worldwide 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 in China, although it may be for the Zhujiang delta. Sea-level rise
due to global warming will, however, exacerbate problems in all three deltas,
along with saltwater intrusion problems in deltaic regions and coastal plains.
China, however, has a long history in defenses against sea encroachment.
Tokyo, Osaka, and Nagoya are all located in the coastal zone; together,
they account for more than 50% of Japan's industrial production. In these
metropolitan areas, already about 860 km2 of coastal land-an area supporting
2 million people and with physical assets worth $450 billion-are below mean
high-water level. With a 1-m rise in mean sea level, the area below mean high-water
level would expand by a factor of 2.7, embracing 4.1 million people and assets
worth more than $900 billion. The same sea-level rise would expand the flood-prone
area from 6,270 km2 to 8,900 km2. The cost of adjusting existing protection
measures has been estimated at about $80 billion.
One of the potential threats that sea-level rise poses is exacerbated beach
erosion. Sandy beaches occupy 20-25% of the total length of the Japanese coast.
About 120 km2 of these beaches have been eroded over the past 70 years. An
additional 118 km2 of beaches-57% of the remaining sandy beaches in Japan
today-would disappear with a 30-cm sea-level rise. This percentage would increase
to 82% and 90% if the sea level rose by 65 cm or 100 cm, respectively.
An increase in the frequency or severity of heat waves would cause an increase
in (predominantly cardiorespiratory) mortality and illness. Studies of urban
populations in Temperate Asia indicate that the number of heat-related deaths
would increase several-fold in response to modeled climate change scenarios
for 2050.
North China-including Beijing, Tianjin, the four provinces (Hebei, Henan,
Shandong, Shanxi), part of Anhui province, and part of inner Mongolia-is an
economic center of the country. It also is a topographic and climatological
entity. Because this region already is at risk from normal climate variability,
it also is likely to be quite vulnerable to long-term secular shifts.
Water resources: Water resources in north China are vulnerable
to climate change because of already low levels of available per capita
water supplies, water projects that already are highly developed, large
changes in river runoff related mainly to variability in flood season,
and rapid economic development. Water resources also are sensitive to
climate change because of the critical dependence of floods on the Asian
monsoon and the ENSO phenomenon.
Agriculture: This region appears to be especially sensitive to
climate change because of potential increases in the soil moisture deficit.
Warming and increased evapotranspiration, along with possible declines
in precipitation, would make it difficult to maintain the current crop
pattern in areas along the Great Wall and would limit the present practice
of cultivating two crops in succession in the Huang-Hai Plains. Although
climate warming may cause northward shifts of subtropical crop areas,
frequent waterlogging in the south and spring droughts in the north would
inhibit the growth of subtropical crops.
Forests: Demands for agriculture as a result of population increases
and changes in the characteristics of arable lands due to climate change
will likely result in large reductions of forest area.
Coastal zones: Climate change will exacerbate the already serious
problem of relative sea-level rise because of tectonic subsidence and
heavy groundwater withdrawal. Defense against sea encroachment would be
the only viable response because of the high concentration of population
and economic activities. Contamination of groundwater by seawater intrusion
would further worsen the water resource shortage problem.
Research needs: (i) Projection of regional climatic scenarios with
high spatial and temporal resolution; (ii) improved hydrological models with
appropriate land-surface parameters under nonstationary climatic conditions;
(iii) multiple-stress impact studies on water resources in international river
basins; (iv) implementation strategies for integrated coastal zone management,
taking climate change into consideration; (v) studies of the interactive effects
of stresses on human health from hot weather and high levels of air pollution;
and (vi) integrated impact studies that consider different sectors and their
response to adaptation strategies.
Conclusion: The major impacts of global warming on Temperate Asia
will likely take the form of large shifts of the boreal forests, the disappearance
of significant portions of mountain glaciers, and shortages in the water supply.
The most critical uncertainty in these estimates stems from the lack of credible
projections of the hydrological cycle under global warming scenarios. The
effects of climate change on the Asian monsoon and the ENSO phenomenon are
among the major uncertainties in the modeling of the hydrological cycle. Projections
of agricultural crop yields are uncertain not only because of the uncertainty
in the hydrological cycle but also because of the potential positive effects
of CO2 and production practices. In the coastal zones, sea-level rise endangers
sandy beaches but remains an anthropogenically induced problem in deltaic
areas. Integrated impact studies that consider multiple stress factors are
needed.