5.2.2. Ecosystems and Biodiversity
Climate change would exacerbate current threats to biodiversity resulting
from land-use/cover change and population pressure in Asia (medium confidence).
Risks to Asia's rich array of living species are climbing. As many as 1,250
of 15,000 higher plant species are threatened in India. Similar trends are evident
in China, Malaysia, Myanmar, and Thailand. Many species and a large population
of many other species in Asia are likely to be exterminated as a result of the
synergistic effects of climate change and habitat fragmentation. In desert ecosystems,
increased frequency of droughts may result in a decline in local forage around
oases, causing mass mortality among local fauna and threatening their existence.
With a 1-m rise in sea level, the Sundarbans (the largest mangrove ecosystems)
of Bangladesh will completely disappear. [11.2.1,
11.2.1.6]
Permafrost degradation resulting from global warming would increase the
vulnerability of many climate-dependent sectors affecting the economy in boreal
Asia (medium confidence). Pronounced warming in high latitudes of the northern
hemisphere could lead to thinning or disappearance of permafrost in locations
where it now exists. Large-scale shrinkage of the permafrost region in boreal
Asia is likely. Poleward movement of the southern boundary of the sporadic zone
also is likely in Mongolia and northeast China. The boundary between continuous
and discontinuous (intermittent or seasonal) permafrost areas on the Tibetan
Plateau is likely to shift toward the center of the plateau along the eastern
and western margins. [11.2.1.5]
The frequency of forest fires is expected to increase in boreal Asia (medium
confidence). Warmer surface air temperatures, particularly during summer,
may create favorable conditions for thunderstorms and associated lightening,
which could trigger forest fires in boreal forests more often. Forest fire is
expected to occur more frequently in northern parts of boreal Asia as a result
of global warming. [11.2.1.3]
5.2.3. Water Resources
Freshwater availability is expected to be highly vulnerable to anticipated
climate change (high confidence). Surface runoff increases during winter
and summer periods would be pronounced in boreal Asia (medium confidence). Countries
in which water use is more than 20% of total potential water resources available
are expected to experience severe water stress during drought periods. Surface
runoff is expected to decrease drastically in arid and semi-arid Asia under
projected climate change scenarios. Climate change is likely to change streamflow
volume, as well as the temporal distribution of streamflows throughout the year.
With a 2°C increase in air temperature accompanied by a 5-10% decline in
precipitation during summer, surface runoff in Kazakhstan would be substantially
reduced, causing serious implications for agriculture and livestocks. Water
would be a scarce commodity in many south and southeast Asian countries, particularly
where reservoir facilities to store water for irrigation are minimal. Growing
populations and concentration of populations in urban areas will exert increasing
pressures on water availability and water quality. [11.2.3.1]
5.2.4. Extreme Weather Events
Developing countries of temperate and tropical Asia already are quite vulnerable
to extreme climate events such as typhoons/cyclones, droughts, and floods. Climate
change and variability would exacerbate these vulnerabilities (high confidence).
Extreme weather events are known to cause adverse effects in widely separated
areas of Asia. There is some evidence of increases in the intensity or frequency
of some of these extreme events on regional scales throughout the 20th century.
[11.1.2.2, 11.1.2.3,
11.4.1]
Increased precipitation intensity, particularly during the summer monsoon,
could increase flood-prone areas in temperate and tropical Asia. There is potential
for drier conditions in arid and semi-arid Asia during summer, which could lead
to more severe droughts (medium confidence). Many countries in temperate
and tropical Asia have experienced severe droughts and floods frequently in
the 20th century. Flash floods are likely to become more frequent in many regions
of temperate and tropical Asia in the future. A decrease in return period for
extreme precipitation events and the possibility of more frequent floods in
parts of India, Nepal, and Bangladesh is projected. [11.1.3.3,
11.2.2.2, 11.1.2.3,
11.4.1]
Conversion of forestland to cropland and pasture already is a prime force driving
forest loss in tropical and temperate Asian countries. With more frequent floods
and droughts, these actions will have far-reaching implications for the environment
(e.g., soil erosion, loss of soil fertility, loss of genetic variability in
crops, and depletion of water resources). [11.1.4.1]
Tropical cyclones and storm surges continue to take a heavy toll on life and
property in India and Bangladesh. An increase in the intensity of cyclones combined
with sea-level rise would result in more loss of life and property in low-lying
coastal areas in cyclone-prone countries of Asia (medium confidence). The expected
increase in the frequency and intensity of climatic extremes will have significant
potential effects on crop growth and agricultural production, as well as major
economic and environmental implications (e.g., tourism, transportation). [11.2.4.5,
11.2.6.3, 11.3]
A wide range of precautionary measures at regional and national levels, including
awareness and acceptance of risk factors among regional communities, is warranted
to avert or reduce the impacts of disasters associated with more extreme weather
events on economic and social structures of countries in temperate and tropical
Asia. [11.3.2]
5.2.5. Deltas and Coastal Zones
The large deltas and low-lying coastal areas of Asia would be inundated
by sea-level rise (high confidence). Climate-related stresses in coastal
areas include loss and salinization of agricultural land as a result of change
in sea level and changing frequency and intensity of tropical cyclones. Estimates
of potential land loss resulting from sea-level rise and risk to population
displacement provided in Table TS-8 demonstrate
the scale of the issue for major low-lying regions of coastal Asia. Currently,
coastal erosion of muddy coastlines in Asia is not a result of sea-level rise;
it is triggered largely by annual river-borne suspended sediments transported
into the ocean by human activities and delta evolution. These actions could
exacerbate the impacts of climate change in coastal regions of Asia. [11.2.4.2]
| Table TS-8: Potential land loss and population exposed
in Asian countries for selected magnitudes of sea-level rise, assuming no
adaptation. |
 |
| |
Sea-Level Rise
(cm)
|
Potential Land Loss
|
Population Exposed
|
|
Country
|
(km2)
|
(%)
|
(million)
|
(%)
|
|
| Bangladesh |
45 |
15,668 |
10.9 |
5.5 |
5.0 |
| |
100 |
29,846 |
20.7 |
14.8 |
13.5 |
| India |
100 |
5,763 |
0.4 |
7.1 |
0.8 |
| Indonesia |
60 |
34,000 |
1.9 |
2.0 |
1.1 |
| Japan |
50 |
1,412 |
0.4 |
2.9 |
2.3 |
| Malaysia |
100 |
7,000 |
2.1 |
>0.05 |
>0.3 |
| Pakistan |
20 |
1,700 |
0.2 |
n.a. |
n.a. |
| Vietnam |
100 |
40,000 |
12.1 |
17.1 |
23.1 |
|
5.2.6. Human Health
Warmer and wetter conditions would increase the potential for higher incidence
of heat-related and infectious diseases in tropical and temperate Asia (medium
confidence). The rise in surface air temperature and changes in precipitation
in Asia will have adverse effects on human health. Although warming would result
in a reduction in wintertime deaths in temperate countries, there could be greater
frequency and duration of heat stress, especially in megalopolises during summer.
Global warming also will increase the incidence of respiratory and cardiovascular
diseases in parts of arid and semi-arid Asia and temperate and tropical Asia.
Changes in environmental temperature and precipitation could expand vector-borne
diseases into temperate and arid Asia. The spread of vector-borne diseases into
more northern latitudes may pose a serious threat to human health. Warmer SSTs
along Asian coastlines would support higher phytoplankton blooms. These blooms
are habitats for infectious bacterial diseases. Waterborne diseases -- including
cholera and the suite of diarrheal diseases caused by organisms such as giardia,
salmonella, and cryptosporidium -- could become more common in many countries
of south Asia in warmer climate. [11.2.5.1,
11.2.5.2, 11.2.5.4]
5.2.7. Adaptive Capacity
Adaptation to climate change in Asian countries depends on the affordability
of adaptive measures, access to technology, and biophysical constraints such
as land and water resource availability, soil characteristics, genetic diversity
for crop breeding (e.g., crucial development of heat-resistant rice cultivars),
and topography. Most developing countries of Asia are faced with increasing
population, spread of urbanization, lack of adequate water resources, and environmental
pollution, which hinder socioeconomic activities. These countries will have
to individually and collectively evaluate the tradeoffs between climate change
actions and nearer term needs (such as hunger, air and water pollution, energy
demand). Coping strategies would have to be developed for three crucial sectors:
land resources, water resources, and food productivity. Adaptation measures
that are designed to anticipate the potential effects of climate change can
help offset many of the negative effects. [11.3.1]
|