1327
24
Asia
Coordinating Lead Authors:
Yasuaki Hijioka (Japan), Erda Lin (China), Joy Jacqueline Pereira (Malaysia)
Lead Authors:
Richard T. Corlett (China), Xuefeng Cui (China), Gregory Insarov (Russian Federation),
Rodel Lasco (Philippines), Elisabet Lindgren (Sweden), Akhilesh Surjan (India)
Contributing Authors:
Elena M. Aizen (USA), Vladimir B. Aizen (USA), Rawshan Ara Begum (Bangladesh),
Kenshi Baba (Japan), Monalisa Chatterjee (USA/India), J. Graham Cogley (Canada),
Noah Diffenbaugh (USA), Li Ding (Singapore), Qingxian Gao (China), Matthias Garschagen
(Germany), Masahiro Hashizume (Japan), Manmohan Kapshe (India), Andrey G. Kostianoy
(Russia), Kathleen McInnes (Australia), Sreeja Nair (India), S.V.R.K. Prabhakar (India),
Yoshiki Saito (Japan), Andreas Schaffer (Singapore), Rajib Shaw (Japan), Dáithí Stone
(Canada/South Africa /USA), Reiner Wassman (Philippines), Thomas J. Wilbanks (USA),
Shaohong Wu (China)
Review Editors:
Rosa Perez (Philippines), Kazuhiko Takeuchi (Japan)
Volunteer Chapter Scientists:
Yuko Onishi (Japan), Wen Wang (China)
This chapter should be cited as:
Hijioka
, Y., E. Lin, J.J. Pereira, R.T. Corlett, X. Cui, G.E. Insarov, R.D. Lasco, E. Lindgren, and A. Surjan, 2014: Asia.
In: Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part B: Regional Aspects. Contribution of
Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change
[Barros, V.R., C.B. Field, D.J. Dokken, M.D. Mastrandrea, K.J. Mach, T.E. Bilir, M. Chatterjee, K.L. Ebi,
Y.O. Estrada, R.C. Genova, B. Girma, E.S. Kissel, A.N. Levy, S. MacCracken, P.R. Mastrandrea, and L.L. White
(eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 1327-1370.
24
1328
Executive Summary.......................................................................................................................................................... 1330
24.1. Introduction .......................................................................................................................................................... 1332
24.2. Major Conclusions from Previous Assessments .................................................................................................... 1332
Box 24-1. What’s New on Asia in AR5? ...................................................................................................................................... 1333
24.3. Observed and Projected Climate Change ............................................................................................................. 1333
24.3.1. Observed Climate Change .............................................................................................................................................................. 1333
24.3.1.1. Temperature .................................................................................................................................................................... 1333
24.3.1.2. Precipitation and Monsoons ............................................................................................................................................ 1333
24.3.1.3. Tropical and Extratropical Cyclones ................................................................................................................................. 1333
24.3.1.4. Surface Wind Speeds ....................................................................................................................................................... 1334
24.3.1.5. Oceans ............................................................................................................................................................................ 1334
24.3.2. Projected Climate Change .............................................................................................................................................................. 1334
24.3.2.1. Tropical and Extratropical Cyclones ................................................................................................................................. 1334
24.3.2.2. Monsoons ........................................................................................................................................................................ 1334
24.3.2.3. Oceans ............................................................................................................................................................................ 1334
24.4. Observed and Projected Impacts, Vulnerabilities, and Adaptation ....................................................................... 1334
24.4.1. Freshwater Resources ..................................................................................................................................................................... 1334
24.4.1.1. Sub-regional Diversity ..................................................................................................................................................... 1334
24.4.1.2. Observed Impacts ............................................................................................................................................................ 1337
24.4.1.3. Projected Impacts ............................................................................................................................................................ 1337
24.4.1.4. Vulnerabilities to Key Drivers ........................................................................................................................................... 1338
24.4.1.5. Adaptation Options ......................................................................................................................................................... 1338
24.4.2. Terrestrial and Inland Water Systems .............................................................................................................................................. 1339
24.4.2.1. Sub-regional Diversity ..................................................................................................................................................... 1339
24.4.2.2. Observed Impacts ............................................................................................................................................................ 1339
24.4.2.3. Projected Impacts ............................................................................................................................................................ 1340
24.4.2.4. Vulnerabilities to Key Drivers ........................................................................................................................................... 1341
24.4.2.5. Adaptation Options ......................................................................................................................................................... 1341
24.4.3. Coastal Systems and Low-Lying Areas ............................................................................................................................................ 1341
24.4.3.1. Sub-regional Diversity ..................................................................................................................................................... 1341
24.4.3.2. Observed Impacts ............................................................................................................................................................ 1342
24.4.3.3. Projected Impacts ............................................................................................................................................................ 1342
24.4.3.4. Vulnerabilities to Key Drivers ........................................................................................................................................... 1342
24.4.3.5. Adaptation Options ......................................................................................................................................................... 1343
24.4.4. Food Production Systems and Food Security ................................................................................................................................... 1343
24.4.4.1. Sub-regional Diversity ..................................................................................................................................................... 1343
24.4.4.2. Observed Impacts ............................................................................................................................................................ 1343
Table of Contents
1329
Asia Chapter 24
24
24.4.4.3. Projected Impacts ............................................................................................................................................................ 1343
24.4.4.4. Vulnerabilities to Key Drivers ........................................................................................................................................... 1345
24.4.4.5. Adaptation Options ......................................................................................................................................................... 1345
24.4.5. Human Settlements, Industry, and Infrastructure ............................................................................................................................ 1346
24.4.5.1. Sub-regional Diversity ..................................................................................................................................................... 1346
24.4.5.2. Observed Impacts ............................................................................................................................................................ 1346
24.4.5.3. Projected Impacts ............................................................................................................................................................ 1346
24.4.5.4. Vulnerabilities to Key Drivers ........................................................................................................................................... 1347
24.4.5.5. Adaptation Options ......................................................................................................................................................... 1347
24.4.6. Human Health, Security, Livelihoods, and Poverty .......................................................................................................................... 1348
24.4.6.1. Sub-regional Diversity ..................................................................................................................................................... 1348
24.4.6.2. Observed Impacts ............................................................................................................................................................ 1348
24.4.6.3. Projected Impacts ............................................................................................................................................................ 1349
24.4.6.4. Vulnerabilities to Key Drivers ........................................................................................................................................... 1350
24.4.6.5. Adaptation Options ......................................................................................................................................................... 1350
24.4.7. Valuation of Impacts and Adaptation ............................................................................................................................................. 1350
24.5. Adaptation and Managing Risks ........................................................................................................................... 1351
24.5.1. Conservation of Natural Resources ................................................................................................................................................. 1351
24.5.2. Flood Risks and Coastal Inundation ................................................................................................................................................ 1351
24.5.3. Economic Growth and Equitable Development .............................................................................................................................. 1351
24.5.4. Mainstreaming and Institutional Barriers ....................................................................................................................................... 1351
24.5.5. Role of Higher Education in Adaptation and Risk Management ..................................................................................................... 1352
24.6. Adaptation and Mitigation Interactions ............................................................................................................... 1352
24.7. Intra-regional and Inter-regional Issues ............................................................................................................... 1353
24.7.1. Transboundary Pollution ................................................................................................................................................................. 1353
24.7.2. Trade and Economy ........................................................................................................................................................................ 1353
24.7.3. Migration and Population Displacement ......................................................................................................................................... 1353
24.8. Research and Data Gaps ....................................................................................................................................... 1353
24.9. Case Studies .......................................................................................................................................................... 1355
24.9.1. Transboundary Adaptation Planning and Management —Lower Mekong River Basin ................................................................... 1355
24.9.2. Glaciers of Central Asia .................................................................................................................................................................. 1355
References ....................................................................................................................................................................... 1356
Frequently Asked Questions
24.1: What will the projected impact of future climate change be on freshwater resources in Asia? ...................................................... 1338
24.2: How will climate change affect food production and food security in Asia? ................................................................................... 1344
24.3: Who is most at risk from climate change in Asia? .......................................................................................................................... 1347
1330
Chapter 24 Asia
24
Executive Summary
Warming trends and increasing temperature extremes have been observed across most of the Asian region over the past century
(high confidence). {24.3} Increasing numbers of warm days and decreasing numbers of cold days have been observed, with the warming
trend continuing into the new millennium. Precipitation trends including extremes are characterized by strong variability, with both increasing
and decreasing trends observed in different parts and seasons of Asia.
Water scarcity is expected to be a major challenge for most of the region as a result of increased water demand and lack of good
management (medium confidence). {24.4.3} Water resources are important in Asia because of the massive population and vary among
regions and seasons. However, there is low confidence in future precipitation projections at a sub-regional scale and thus in future freshwater
availability in most parts of Asia. Population growth and increasing demand arising from higher standards of living could worsen water security
in many parts in Asia and affect many people in the future. Integrated water management strategies could help adapt to climate change,
including developing water-saving technologies, increasing water productivity, and water reuse.
The impacts of climate change on food production and food security in Asia will vary by region, with many regions to experience
a decline in productivity (medium confidence). {24.4.4}
This is evident in the case of rice production. Most models, using a range of
General Circulation Models (GCMs) and Special Report on Emission Scenarios (SRES) scenarios, show that higher temperatures will lead to
lower rice yields as a result of shorter growing periods. There are a number of regions that are already near the heat stress limits for rice.
However, carbon dioxide (CO
2
) fertilization may at least in part offset yield losses in rice and other crops. In Central Asia, some areas could be
winners (cereal production in northern and eastern Kazakhstan could benefit from the longer growing season, warmer winters, and slight
increase in winter precipitation), while others could be losers (western Turkmenistan and Uzbekistan, where frequent droughts could negatively
affect cotton production, increase water demand for irrigation, and exacerbate desertification). In the Indo-Gangetic Plains of South Asia there
could be a decrease of about 50% in the most favorable and high-yielding wheat area as a result of heat stress at 2 times CO
2
. Sea level rise
will inundate low-lying areas and will especially affect rice growing regions. Many potential adaptation strategies are being practiced and
proposed but research studies on their effectiveness are still few.
Terrestrial systems in many parts of Asia have responded to recent climate change with shifts in the phenologies, growth rates,
and the distributions of plant species, and with permafrost degradation, and the projected changes in climate during the 21st
century will increase these impacts (high confidence). {24.4.2}
Boreal trees will likely invade treeless arctic vegetation, while evergreen
conifers will likely invade deciduous larch forest. Large changes may also occur in arid and semiarid areas, but uncertainties in precipitation
projections make these more difficult to predict. The rates of vegetation change in the more densely populated parts of Asia may be reduced by
the impact of habitat fragmentation on seed dispersal, while the impacts of projected climate changes on the vegetation of the lowland tropics
are currently poorly understood. Changes in animal distributions have also been projected, in response to both direct impacts of climate
change and indirect impacts through changes in the availability of suitable habitats.
Coastal and marine systems in Asia are under increasing stress from both climatic and non-climatic drivers (high confidence).
{24.4.3}
It is likely that mean sea level rise will contribute to upward trends in extreme coastal high water levels. {WGI AR5 3.7.6} In the Asian
Arctic, rising sea levels are expected to interact with projected changes in permafrost and the length of the ice-free season to cause increased
rates of coastal erosion (medium evidence, high agreement). Mangroves, salt marshes, and seagrass beds may decline unless they can move
inland, while coastal freshwater swamps and marshes will be vulnerable to saltwater intrusion with rising sea levels. Widespread damage to
coral reefs correlated with episodes of high sea surface temperature has been reported in recent decades and there is high confidence that
damage to reefs will increase during the 21st century as a result of both warming and ocean acidification. Marine biodiversity is expected to
increase at temperate latitudes as warmwater species expand their ranges northward (high confidence), but may decrease in the tropics if
thermal tolerance limits are exceeded (medium confidence).
Multiple stresses caused by rapid urbanization, industrialization, and economic development will be compounded by climate
change (high confidence). {24.4-7}
Climate change is expected to adversely affect the sustainable development capabilities of most Asian
developing countries by aggravating pressures on natural resources and the environment. Development of sustainable cities in Asia with fewer
fossil fuel-driven vehicles and with more trees and greenery would have a number of co-benefits, including improved public health.
1331
24
Asia Chapter 24
Extreme climate events will have an increasing impact on human health, security, livelihoods, and poverty, with the type and
magnitude of impact varying across Asia (high confidence). {24.4.6}
More frequent and intense heat waves in Asia will increase mortality
and morbidity in vulnerable groups. Increases in heavy rain and temperature will increase the risk of diarrheal diseases, dengue fever, and
malaria. Increases in floods and droughts will exacerbate rural poverty in parts of Asia as a result of negative impacts on the rice crop and
resulting increases in food prices and the cost of living.
Studies of observed climate changes and their impacts are still inadequate for many areas, particularly in North, Central, and
West Asia (high confidence). {24.8} Improved projections for precipitation, and thus water supply, are most urgently needed. Understanding
of climate change impacts on ecosystems in Asia is currently limited by the incompleteness and inaccessibility of biodiversity information.
Major research gaps in the tropics include the temperature dependence of carbon fixation by tropical trees and the thermal tolerances and
acclimation capacities of both plants and animals. Interactions between climate change and the direct impacts of rising CO
2
on crops and natural
ecosystems are also currently poorly understood. More research is needed on impacts, vulnerability, and adaptation in urban settlements,
especially cities with populations of less than 500,000. More generally, there is a need to develop low-cost adaptation measures appropriate to
the least developed parts of the region.
1332
Chapter 24 Asia
24
24.1. Introduction
Asia is defined here as the land and territories of 51 countries/regions
(see Figure 24-1). It can be broadly divided into six subregions based on
geographical position and coastal peripheries. These are, in alphabetical
order, Central Asia (5 countries), East Asia (7 countries/regions), North
Asia (2 countries), South Asia (8 countries), Southeast Asia (12 countries),
and West Asia (17 countries). The population of Asia was reported to be
about 4299 million in 2013, which is about 60% of the world population
(UN DESA Population Division, 2013). Population density was reportedly
about 134 per square kilometer in 2012 (PRB, 2012). The highest life
expectancy at birth is 84 (Japan) and the lowest is 50 (Afghanistan)
(CIA, 2013). The gross domestic product (GDP) per capita ranged from
US$620 (Afghanistan for 2011) to US$51,709 (Singapore for 2012)
(World Bank, 2013).
24.2. Major Conclusions
from Previous Assessments
Major highlights from previous assessments for Asia include:
Warming trends, including higher extremes, are strongest over the
continental interiors of Asia, and warming in the period 1979 onward
was strongest over China in winter, and northern and eastern Asia
in spring and autumn (WGI AR4 Section 3.2.2.7; SREX Section 3.3.1).
From 1900 to 2005, precipitation increased significantly in northern
and central Asia but declined in parts of southern Asia (WGI AR4
SPM).
Future climate change is likely to affect water resource scarcity with
enhanced climate variability and more rapid melting of glaciers
(WGII AR4 Section 10.4.2).
Increased risk of extinction for many plant and animal species in
Asia is likely as a result of the synergistic effects of climate change
and habitat fragmentation (WGII AR4 Section 10.4.4).
Projected sea level rise is very likely to result in significant losses
of coastal ecosystems (WGII AR4 Sections 10.4.3.2, 10.6.1).
There will be regional differences within Asia in the impacts of climate
change on food production (WGII AR4 Section 10.4.1.1).
Due to projected sea level rise, a million or so people along the
coasts of South and Southeast Asia will likely be at risk from flooding
(high confidence; WGII AR4 Section 10.4.3.1).
It is likely that climate change will impinge on sustainable development
of most developing countries of Asia as it compounds the pressures
on natural resources and the environment associated with rapid
urbanization, industrialization, and economic development (WGII
AR4 Section 10.7).
Vulnerabilities of industry, infrastructure, settlements, and society
to climate change are generally greater in certain high-risk
locations, particularly coastal and riverine areas (WGII AR4 Sections
7.3-5).
East Asia (7)
China, Hong Kong Special
Administrative Region
(Hong Kong SAR)
China, Macao Special
Administrative Region
Japan
North Korea
People’s Republic of China
(China)
South Korea
Taiwan Province of China
(Taiwan POC)
Kazakhstan
Kyrgyzstan
Tajikistan
Turkmenistan
Uzbekistan
Central Asia (5)
North Asia (2)
South Asia (8)
Southeast Asia (12)
West Asia (17)
Mongolia
Russia (East of Urals)
Afghanistan
Bangladesh
Bhutan
India
Maldives
Nepal
Pakistan
Sri Lanka
Brunei
Indonesia
Lao People's
Democratic Republic
Malaysia
Myanmar
Papua New Guinea
The Philippines
People’s Republic of
Cambodia
Singapore
Thailand
Timor-Leste
Vietnam
Armenia
Azerbaijan
Bahrain
Georgia
Iran
Iraq
Israel
Jordan
Kuwait
Lebanon
Palestine
Oman
Qatar
Saudi Arabia
Syria
United Arab Emirates
Yemen
Figure 24-1 | The land and territories of 51 countries/regions in Asia. Maps contained in this report are only for the purpose of geographic information reference.
1333
24
Asia Chapter 24
24.3. Observed and Projected Climate Change
24.3.1. Observed Climate Change
24.3.1.1. Temperature
It is very likely that mean annual temperature has increased over the
past century over most of the Asia region, but there are areas of the
interior and at high latitudes where the monitoring coverage is insufficient
for the assessment of trends (see WGI AR5 Chapter 2; Figure 24-2). New
analyses continue to support the Fourth Assessment Report (AR4) and
IPCC Special Report on Managing the Risks of Extreme Events and
Disasters to Advance Climate Change Adaptation (SREX) conclusions
that it is likely that the numbers of cold days and nights have decreased
and the numbers of warm days and nights have increased across most
of Asia since about 1950, and heat wave frequency has increased since
the middle of the 20th century in large parts of Asia (see WGI AR5 Section
2.6.1).
As a part of the polar amplification, large warming trends (>2°C per
50 years) in the second half of the 20th century were observed in the
northern Asian sector (see WGI AR5 Section 14.8.8). Over the period
1901–2009, the warming trend was particularly strong in the cold season
between November and March, with an increase of 2.4°C in the mid-
latitude semiarid area of Asia (see WGI AR5 Section 14.8.8). Increasing
annual mean temperature trends at the country scale in East and South
Asia have been observed during the 20th century (Table SM24-1). In
West Asia, upward temperature trends are notable and robust in recent
d
ecades (WGI AR5 Section 14.8.10). Across Southeast Asia, temperature
has been increasing at a rate of 0.14°C to 0.20°C per decade since the
1960s, coupled with a rising number of hot days and warm nights, and
a decline in cooler weather (see WGI AR5 Section 14.8.12).
24.3.1.2. Precipitation and Monsoons
Most areas of the Asian region lack sufficient observational records to
draw conclusions about trends in annual precipitation over the past
century (see WGI AR5 Chapter 2; Figure 24-2; Table SM24-2). Precipitation
trends, including extremes, are characterized by strong variability, with
both increasing and decreasing trends observed in different parts and
seasons of Asia (see WGI AR5 Chapter 14; Table SM24-2). In northern Asia,
the observations indicate some increasing trends of heavy precipitation
events, but in central Asia, no spatially coherent trends were found (see
WGI AR5 Section 14.8.8). Both the East Asian summer and winter monsoon
circulations have experienced an inter-decadal scale weakening after the
1970s, due to natural variability of the coupled climate system, leading
to enhanced mean and extreme precipitation along the Yangtze River
valley (30°N), but deficient mean precipitation in North China in summer
(see WGI AR5 Section 14.8.9). A weakening of the East Asian summer
monsoon since the 1920s was also found in sea level pressure gradients
(low confidence; see WGI AR5 Section 2.7.4). In West Asia, a weak but
non-significant downward trend in mean precipitation was observed in
recent decades, although with an increase in intense weather events
(see WGI AR5 Section 14.8.10). In South Asia, seasonal mean rainfall
shows inter-decadal variability, noticeably a declining trend with more
frequent deficit monsoons under regional inhomogeneities (see WGI AR5
Section 14.8.11). Over India, the increase in the number of monsoon
break days and the decline in the number of monsoon depressions are
consistent with the overall decrease in seasonal mean rainfall (see
WGI AR5 Section 14.8.11). But an increase in extreme rainfall events
occurred at the expense of weaker rainfall events over the central Indian
region and in many other areas (see WGI AR5 Section 14.2.2.1). In South
Asia, the frequency of heavy precipitation events is increasing, while
light rain events are decreasing (see WGI AR5 Section 14.8.11). In
Southeast Asia, annual total wet-day rainfall has increased by 22 mm
per decade, while rainfall from extreme rain days has increased by 10
mm per decade, but climate variability and trends differ vastly across the
region and between seasons (see WGI AR5 Sections 14.4.12, 14.8.12).
In Southeast Asia, between 1955 and 2005 the ratio of rainfall in the
wet to the dry seasons increased. While an increasing frequency of
extreme events has been reported in the northern parts of Southeast
Asia, decreasing trends in such events are reported in Myanmar (see
WGI AR5 Section 14.4.12). In Peninsular Malaya during the southwest
monsoon season, total rainfall and the frequency of wet days decreased,
but rainfall intensity increased in much of the region. On the other hand,
during the northeast monsoon, total rainfall, the frequency of extreme
rainfall events, and rainfall intensity all increased over the peninsula
(see WGI AR5 Section 14.4.12).
24.3.1.3. Tropical and Extratropical Cyclones
Significant trends in tropical cyclones making landfall are not found on
shorter timescales. Time series of cyclone indices show weak upward
Box 24-1 | What’s New on Asia in AR5?
There is improved country coverage on observed and
future impacts of climate change.
There is an increase in the number of studies reflecting
advances in research tools (e.g., more use of remote
sensing and modeling of impacts), with an evaluation
of detection and attribution where feasible.
More conclusions have confidence statements, while
confidence levels have changed in both directions
since AR4.
Expanded coverage of issues—for example, discussion
of the Himalayas has been expanded to cover observed
and projected impacts (Box 3-2), including those on
tourism (see Section 10.6.2); livelihood assets such as
water and food (Sections 9.3.3.1, 13.3.1.1, 18.5.3,
19.6.3); poverty (Section 13.3.2.3); culture (Section
12.3.2); flood risks (Sections 18.3.1.1, 24.2.1); health
risks (Section 24.4.6.2); and ecosystems (Section
24.4.2.2).
1334
Chapter 24 Asia
24
t
rends in the western North Pacific since the late 1970s, but interpretation
of longer term trends is constrained by data quality concerns (see WGI
AR5 Section 2.6.3). A decrease in extratropical cyclone activity and
intensity over the last 50 years has been reported for northern Eurasia
(60°N to 40°N), including lower latitudes in East Asia (see WGI AR5
Section 2.6.4).
24.3.1.4. Surface Wind Speeds
Over land in China, including the Tibetan region, a weakening of the
seasonal and annual mean winds, as well as the maximums, is reported
from around the 1960s or 1970s to the early 2000s (low confidence;
see WGI AR5 Section 2.7.2).
24.3.1.5. Oceans
A warming maximum is observed at 25°N to 65°N with signals extending
to 700 m depth and is consistent with poleward displacement of the
mean temperature field (WGI AR5 Section 3.2.2). The pH measurements
between 1983 and 2008 in the western North Pacific showed a –0.0018
± 0.0002 yr
1
decline in winter and –0.0013 ± 0.0005 yr
1
decline in
summer (see WGI AR5 Section 3.8.2). Over the period 1993–2010, large
rates of sea level rise in the western tropical Pacific were reported,
corresponding to an increase in the strength of the trade winds in the
central and eastern tropical Pacific (see WGI AR5 Section 13.6.1). Spatial
variation in trends in Asian regional sea level may also be specific to a
particular sea or ocean basin. For example, a rise of 5.4 ± 0.3 mm yr
–1
in the Sea of Japan from 1993 to 2001 is nearly two times the global
mean sea level (GMSL) trend, with more than 80% of this rise being
thermosteric, and regional changes of sea level in the Indian Ocean that
have emerged since the 1960s are driven by changing surface winds
associated with a combined enhancement of Hadley and Walker cells
(see WGI AR5 Section 13.6.1).
24.3.2. Projected Climate Change
The AR4 assessed that warming is very likely in the 21st century
(Christensen et al., 2007), and that assessment still holds for all land
areas of Asia in the mid- and late-21st century, based on the Coupled
Model Intercomparison Project Phase 5 (CMIP5) simulations under all
four Representative Concentration Pathway (RCP) scenarios (Figures
24-2, SM24-1; Table SM24-3). Ensemble-mean changes in mean annual
temperature exceed 2°C above the late-20th-century baseline over most
land areas in the mid-21st century under RCP8.5, and range from
greater than 3°C over South and Southeast Asia to greater than 6°C
over high latitudes in the late-21st century. The ensemble-mean changes
are less than 2°C above the late-20th-century baseline in both the mid-
and late-21st century under RCP2.6, with the exception of changes
between 2°C and 3°C over the highest latitudes.
Projections of future annual precipitation change are qualitatively similar
to those assessed in the AR4 (Christensen et al., 2007; see Figure 24-2).
Precipitation increases are very likely at higher latitudes by the mid-
21st century under the RCP8.5 scenario, and over eastern and southern
a
reas by the late-21st century. Under the RCP2.6 scenario, increases are
likely at high latitudes by the mid-21st century, while it is likely that
changes at low latitudes will not substantially exceed natural variability.
24.3.2.1. Tropical and Extratropical Cyclones
The future influence of climate change on tropical cyclones is likely to
vary by region, but there is low confidence in region-specific projections
of frequency and intensity. However, better process understanding and
model agreement in specific regions indicate that precipitation will likely
be more extreme near the centers of tropical cyclones making landfall
in West, East, South, and Southeast Asia (see WGI AR5 Sections 14.6,
14.8.9-12). There is medium confidence that a projected poleward shift
in the North Pacific storm track of extratropical cyclones is more likely
than not. There is low confidence in the magnitude of regional storm track
changes and the impact of such changes on regional surface climate (see
WGI AR5 Section 14.6).
24.3.2.2. Monsoons
Future increases in precipitation extremes related to the monsoon are
very likely in East, South, and Southeast Asia (see WGI AR5 Sections
14.2.1, 14.8.9, 14.8.11-12). More than 85% of CMIP5 models show an
increase in mean precipitation in the East Asian summer monsoons, while
more than 95% of models project an increase in heavy precipitation
events (see WGI AR5 Section 14.2.2, Figure 14.4). All models and all
scenarios project an increase in both the mean and extreme precipitation
in the Indian summer monsoon (see WGI AR5 Section 14.2.2 and Southern
Asia (SAS) in Figure 14.4). In these two regions, the interannual standard
deviation of seasonal mean precipitation also increases (see WGI AR5
Section 14.2.2).
24.3.2.3. Oceans
The ocean in subtropical and tropical regions will warm in all RCP
scenarios and will show the strongest warming signal at the surface
(WGI AR5 Section 12.4.7, Figure 12.12). Negligible change or a decrease
in mean significant wave heights are projected for the trade and monsoon
wind regions of the Indian Ocean (see WGI AR5 Section 13.7.3).
24.4. Observed and Projected Impacts,
Vulnerabilities, and Adaptation
Key observed and projected climate change impacts are summarized in
Tables 24-1, SM24-4, and SM24-5 (based on Sections 24.4.1-6).
24.4.1. Freshwater Resources
24.4.1.1. Sub-regional Diversity
Freshwater resources are very important in Asia because of the massive
population and heavy economic dependence on agriculture, but water
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24
Asia Chapter 24
Diagonal Lines
Trend not
statistically
significant
White
Insufficient
data
Solid Color
Strong
agreement
Very strong
agreement
Little or
no change
Gray
Divergent
changes
Solid Color
Significant
trend
Diagonal Lines
White Dots
late 21st century
mid 21st century
RCP8.5RCP2.6
Figure 24-2 | Observed and projected changes in annual average temperature and precipitation in Asia. (Top panel, left) Map of observed annual average temperature change
from 1901–2012, derived from a linear trend. [WGI AR5 Figures SPM.1 and 2.21] (Bottom panel, left) Map of observed annual precipitation change from 1951–2010, derived
from a linear trend. [WGI AR5 Figures SPM.2 and 2.29] For observed temperature and precipitation, trends have been calculated where sufficient data permit a robust estimate
(i.e., only for grid boxes with greater than 70% complete records and more than 20% data availability in the first and last 10% of the time period). Other areas are white. Solid
colors indicate areas where trends are significant at the 10% level. Diagonal lines indicate areas where trends are not significant. (Top and bottom panel, right) CMIP5
multi-model mean projections of annual average temperature changes and average percent changes in annual mean precipitation for 2046–2065 and 2081–2100 under RCP2.6
and 8.5, relative to 1986–2005. Solid colors indicate areas with very strong agreement, where the multi-model mean change is greater than twice the baseline variability (natural
internal variability in 20-yr means) and ≥90% of models agree on sign of change. Colors with white dots indicate areas with strong agreement, where ≥66% of models show
change greater than the baseline variability and ≥66% of models agree on sign of change. Gray indicates areas with divergent changes, where ≥66% of models show change
greater than the baseline variability, but <66% agree on sign of change. Colors with diagonal lines indicate areas with little or no change, where <66% of models show change
greater than the baseline variability, although there may be significant change at shorter timescales such as seasons, months, or days. Analysis uses model data and methods
building from WGI AR5 Figure SPM.8. See also Annex I of WGI AR5. [Boxes 21-2 and CC-RC]
late 21st century
mid 21st century
RCP8.5RCP2.6
Annual Precipitation
Change
Annual Temperature Change
Difference from 19862005 mean (%)
Difference from 19862005 mean
(˚C)
Trend over 19012012
(˚C over period)
02 46
20 0 20 40
(mm/year per decade)
Trend in annual precipitation over 1951–2010
5 0525102.52.5 501050 25100
1336
Chapter 24 Asia
24
K
ey risk
Adaptation issues & prospects
Climatic
drivers
Risk & potential for
adaptation
T
imeframe
D
amaging
c
yclone
O
cean
a
cidification
D
rying
t
rend
C
OO
Climate-related drivers of impacts
W
arming
t
rend
E
xtreme
p
recipitation
E
xtreme
t
emperature
S
ea
l
evel
Level of risk & potential for adaptation
P
otential for additional adaptation
to reduce risk
Risk level with
current adaptation
Risk level with
high adaptation
Table 24-1 | Key risks from climate change and the potential for risk reduction through mitigation and adaptation in Asia. Key risks are identified based on assessment of the
l
iterature and expert judgments, with supporting evaluation of evidence and agreement in the referenced chapter sections. Each key risk is characterized as very low, low,
medium, high, or very high. Risk levels are presented for the near-term era of committed climate change (here, for 2030–2040), in which projected levels of global mean
temperature increase do not diverge substantially across emissions scenarios. Risk levels are also presented for the longer term era of climate options (here, for 2080–2100), for
global mean temperature increase of 2°C and 4°C above pre-industrial levels. For each time frame, risk levels are estimated for the current state of adaptation and for a
hypothetical highly adapted state. As the assessment considers potential impacts on different physical, biological, and human systems, risk levels should not necessarily be used
to evaluate relative risk across key risks. Relevant climate variables are indicated by symbols.
Near term
(2030-2040)
Present
Long term
(2080–2100)
2°C
4°C
V
ery
low
V
ery
high
M
edium
Near term
(
2030–2040)
Present
Long term
(2080–2100)
2°C
4°C
Very
l
ow
Very
h
igh
Medium
Near term
(2030–2040)
Present
Long-term
(2080–2100)
2°C
4°C
V
ery
l
ow
V
ery
h
igh
Medium
Near term
(2030–2040)
Present
Long term
(2080–2100)
2°C
4°C
Very
low
Very
high
Medium
Near term
(2030–2040)
Present
Long term
(2080–2100)
2°C
4°C
Very
low
Very
high
Medium
I
ncreased risk of crop failure and lower
crop production could lead to food
insecurity in Asia (medium confidence)
[24.4.4]
A
utonomous adaptation of farmers on-going in many parts of Asia.
Water shortage in arid areas of Asia
(
medium confidence)
[24.4.1.3, 24.4.1.4]
Limited capacity for water resource adaptation; options include
d
eveloping water saving technology, changing drought-resilient crops,
b
uilding more water reservoirs.
Increased riverine, coastal, and urban
flooding leading to widespread
damage to infrastructure, livelihoods,
and settlements in Asia
(medium confidence)
[24.4]
Exposure reduction via structural and non-structural measures, effective
land-use planning, and selective relocation
Reduction in the vulnerability of lifeline infrastructure and services (e.g., water,
energy, waste management, food, biomass, mobility, local ecosystems,
telecommunications)
Construction of monitoring and early warning systems; Measures to identify
exposed areas, assist vulnerable areas and households, and diversify livelihoods
Economic diversication
Increased risk of flood-related deaths,
injuries, infectious diseases and mental
disorders (medium confidence)
[24.4.6.2, 24.4.6.3, 24.4.6.5]
Disaster preparedness including early-warning systems and local coping
strategies.
Increased risk of heat-related mortality
(high confidence)
[24.4]
• Heat health warning systems
• Urban planning to reduce heat islands; Improvement of the built
environment; Development of sustainable cities
• New work practices to avoid heat stress among outdoor workers
Near term
(2030–2040)
Present
Long term
(2080–2100)
2°C
4°C
Very
low
Very
high
Medium
Near term
(2030–2040)
Present
Long term
(2080–2100)
2°C
4°C
Very
low
Very
high
Medium
Increased risk of drought-related water
and food shortage causing malnutrition
(high confidence)
[24.4]
• Disaster preparedness including early-warning systems and local coping
strategies
Adaptive/integrated water resource management
Water infrastructure and reservoir development
• Diversification of water sources including water re-use
• More efficient use of water (e.g., improved agricultural practices,
irrigation management, and resilient agriculture)
Increased risk of water and vector-borne
diseases (medium confidence)
[24.4.6.2, 24.4.6.3, 24.4.6.5]
Early-warning systems, vector control programs, water management and
sanitation programs.
1337
24
Asia Chapter 24
availability is highly uneven and requires assessment on the sub-
regional scale because of Asia’s huge range of climates (Pfister et al.,
2009).
Adequate water supply is one of the major challenges in many regions
(Vörösmarty et al., 2010), particularly Central Asia. Growing demand
for water is driven by soaring populations, increasing per capita domestic
use due to urbanization and thriving economic growth, and increasing
use of irrigation.
24.4.1.2. Observed Impacts
The impact of changes in climate, particularly precipitation, on water
resources varies cross Asia (Table SM24-4). There is medium confidence
that water scarcity in northern China has been exacerbated by decreasing
precipitation, doubling population, and expanding water withdrawal
(Xu et al., 2010). There is no evidence that suggests significant changes
of groundwater in the Kherlen River Basin in Mongolia over the past
half century (Brutsaert and Sugita, 2008). Apart from water availability,
there is medium confidence that climate change also leads to degradation
of water quality in most regions of Asia (Delpla et al., 2009; Park et al.,
2010), although this is also heavily influenced by human activities
(Winkel et al., 2011).
Glaciers are important stores of water and any changes have the
potential to influence downstream water supply in the long term (see
Section 24.9.2). Glacier mass loss shows a heterogeneous pattern across
Asia (Gardner et al., 2013).
Glaciers in the polar section of the Ural Mountains; in the Kodar
Mountains of Southeast Siberia; in the Suntar Khayata and Chersky
Ranges of Northeast Siberia; in Georgia and Azerbaijan on the southern
flank of the Greater Caucasus Range; on the Tibetan Plateau (see Box
3-1) and the surrounding areas; and on Puncak Jaya, Papua, Indonesia
lost 9 to 80% of their total area in different periods within the 1895–
2010 time interval (Ananicheva et al., 2005, 2006; Anisimov et al., 2008;
Prentice and Glidden, 2010; Allison, 2011; Shahgedanova et al., 2012;
Yao, T. et al., 2012; Stokes et al., 2013) due to increased temperature
(Casassa et al., 2009; Shrestha and Aryal, 2011). Changes in the Kamchatka
glaciers are driven by both warming and volcanic activity, with the area
of some glaciers decreasing, while others increased because they are
covered by ash and clinker (Anisimov et al., 2008).
24.4.1.3. Projected Impacts
Projected impacts of climate change on future water availability in Asia
differ substantially among river basins and seasons (A1B scenario with
five General Circulation Models (GCMs): Immerzeel et al., 2010; A1B
with Meteorological Research Institute of Japan Meteorological Agency
(MRI)-Atmospheric General Circulation Models (AGCMs): Nakaegawa
et al., 2013). There is high confidence that water demand in most
Asian countries is increasing because of increases in population, irrigated
agriculture (Lal, 2011), and industry.
24.4.1.3.1. Tropical Asia
Future projections (A1B with MRI-AGCMs) suggest a decrease in
river runoff in January in the Chao Phraya River basin in Thailand
(Champathong et al., 2013). In a study of the Mahanadi River Basin in
India, a water availability projection (A2, Coupled General Circulation
Model 2 (CGCM2)) indicated increasing possibility of floods in September
but increasing water scarcity in April (Asokan and Dutta, 2008).
In the Ganges, an increase in river runoff could offset the large increases
in water demand due to population growth in a +4ºC world (ensemble
Table 24-1 (continued)
Key risk
Adaptation issues & prospects
Climatic
drivers
Risk & potential for
adaptation
Timeframe
N
ear term
(2030–2040)
Present
Long term
(2080–2100)
2°C
4°C
Very
l
ow
Very
h
igh
Medium
N
ear term
(2030–2040)
Present
Long term
(2080–2100)
2°C
4°C
Very
l
ow
Very
h
igh
M
edium
Near term
(
2030–2040)
Present
Long term
(2080–2100)
2°C
4°C
V
ery
low
V
ery
high
Medium
Exacerbated poverty, inequalities and new
v
ulnerabilities (high confidence)
[
24.4.5, 24.4.6]
Insufficient emphasis and limited understanding on urban poverty,
i
nteraction between livelihoods, poverty and climate change.
Coral reef decline in Asia (high confidence)
[
24.4.3.3, 24.4.3.5, CC-CR, CC-OA]
The limited adaptation options include minimizing additional stresses in
marine protected areas sited where sea surface temperatures are expected
t
o change least and reef resilience is expected to be highest.
Mountain-top extinctions in Asia
(high confidence)
[
24.4.2.4, 24.4.2.5]
Adaptation options are limited. Reducing non-climate impacts and
maximizing habitat connectivity will reduce risks to some extent, while
a
ssisted migration may be practical for some species.
C
O
O
1338
Chapter 24 Asia
24
GCMs), due to a projected large increase in average rainfall, although
high uncertainties remain at the seasonal scale (Fung et al., 2011).
24.4.1.3.2. Northern and temperate Asia
Projections (A2 and B2 with the Global Assessment of Security (GLASS)
model) suggest an increase in average water availability in Russia in
the 2070s (Alcamo et al., 2007). In China, a projection (downscaling
Hadley Centre Atmospheric Model version 3H (HadAM3H) A2 and B2
scenarios with the Providing Regional Climates for Impacts Studies
(PRECIS) regional model) suggests that there will be insufficient water
for agriculture in the 2020s and 2040s due to the increases in water
demand for non-agricultural uses, although precipitation may increase
in some areas (Xiong et al., 2010). In the late-21st century (MRI-AGCMs,
A1B), river discharge in northern Japan is projected to increase in
February but decrease in May, due to increased winter precipitation and
decreased spring snowmelt (Sato et al., 2013).
24.4.1.3.3. Central and West Asia
Given the already very high level of water stress in many parts of Central
Asia, projected temperature increases and precipitation decreases (SRES
scenarios from IPCC AR4, 23 models) in the western part of Kazakhstan,
Uzbekistan, and Turkmenistan could exacerbate the problems of water
shortage and distribution (Lioubimtseva and Henebry, 2009). Considering
the dependence of Uzbekistan’s economy on its irrigated agriculture,
which consumes more than 90% of the available water resources of
the Amu Darya basin, climate change impacts on river flows would also
strongly affect the economy (Schlüter et al., 2010).
24.4.1.4. Vulnerabilities to Key Drivers
It is suggested that freshwater resources will be influenced by changes
in rainfall variability, snowmelt, glacier retreat (Im et al., 2010; Li, Z. et
al., 2010; Sato et al., 2012; Yamanaka et al., 2012; Nakaegawa et al.,
2013), or evapotranspiration in the river catchment, which are associated
with climate change (Jian et al., 2009). Mismanagement of water resources
has increased tension because of water scarcity in arid areas (Biswas and
Seetharam, 2008; Lioubimtseva and Henebry, 2009; Siegfried et al., 2010;
Aarnoudse et al., 2012). Unsustainable consumption of groundwater
for irrigation and other uses is considered to be the main cause of
groundwater depletion in the Indian states of Rajasthan, Punjab, and
Haryana (Rodell et al., 2009).
24.4.1.5. Adaptation Options
Adaptation of freshwater resources to climate change can be identified
as developing adaptive/integrated water resource management (Sadoff
and Muller, 2009; Schlüter et al., 2010) of the trade-offs balancing water
availability against increasing demand, in order to cope with uncertainty
and change (Molle and Hoanh, 2009).
Examples of the options include: developing water saving technologies
in irrigation (Ngoundo et al., 2007); water infrastructure development
in the Ganges river basin (Bharati et al., 2011); increasing water
productivity in the Indus and Ganges river basins (Cai et al., 2010),
Taiwan, China, and the Philippines (Barker and Levine, 2012), and
Uzbekistan (Tischbein et al., 2011); changing cropping systems and
patterns in West Asia (Thomas, 2008); and water reuse in China (Yi et
al., 2011). During the second half of the 20th century, Asia built many
reservoirs and almost tripled its surface water withdrawals for irrigation
(Biemans et al., 2011). Reservoirs partly mitigate seasonal differences
and increase water availability for irrigation (Biemans et al., 2011).
Water management in river basins would benefit from integrated
coordination among countries (Kranz et al., 2010). For example, water
management in the Syr Darya river basin relates to Kyrgyzstan,
Tajikistan, Uzbekistan, Turkmenistan, and Kazakhstan (Siegfried et al.,
2010), while the Indus and Ganges-Brahmaputra-Meghna river basins
concern Bangladesh, India, Nepal, and Pakistan (Uprety and Salman,
2011).
Frequently Asked Questions
FAQ 24.1 | What will the projected impact of future climate change
be on freshwater resources in Asia?
Asia is a huge and diverse region, so both climate change and the impact on freshwater resources will vary greatly
d
epending on location. But throughout the region, adequate water resources are particularly important because
of the massive population and heavy dependence of the agricultural sector on precipitation, river runoff, and
groundwater. Overall, there is low confidence in the projections of specifically how climate change will impact future
p
recipitation on a sub-regional scale, and thus in projections of how climate change might impact the availability
of water resources. However, water scarcity is expected to be a big challenge in many Asian regions because of
increasing water demand from population growth and consumption per capita with higher standards of living.
S
hrinkage of glaciers in central Asia is expected to increase as a result of climate warming, which will influence
downstream river runoff in these regions. Better water management strategies could help ease water scarcity.
Examples include developing water saving technologies in irrigation, building reservoirs, increasing water productivity,
changing cropping systems, and water reuse.
1339
24
Asia Chapter 24
24.4.2. Terrestrial and Inland Water Systems
24.4.2.1. Sub-regional Diversity
Boreal forests and grasslands dominate in North Asia, deserts and semi-
deserts in Central and West Asia, and alpine ecosystems on the Tibetan
Plateau. Human-dominated landscapes predominate in the other sub-
regions, but the major natural ecosystems are temperate deciduous and
subtropical evergreen forests in East Asia, with boreal forest in the
northeast and grasslands and deserts in the west, while Southeast Asia
was largely covered in tropical forests. South Asia also has tropical
forests, with semi-desert in the northwest and alpine ecosystems in the
north. Asia includes several of the world’s largest river systems, as well
as the worlds deepest freshwater lake, Lake Baikal, the semi-saline
Caspian Sea, and the saline Aral Sea.
24.4.2.2. Observed Impacts
Biological changes consistent with climate trends have been reported in
the north and at high altitudes, where rising temperatures have relaxed
constraints on plant growth and the distributions of organisms. Few
changes have been reported from tropical lowlands and none linked to
climate change with high confidence, although data are insufficient to
distinguish lack of observations from lack of impacts. Impacts on inland
water systems have been difficult to disentangle from natural variability
and other human impacts (Bates et al., 2008; Vörösmarty et al., 2010;
Zheng, 2011; see Section 4.3.3.3). For example, the shrinking of the Aral
Sea over the last 50 years has resulted largely from excessive water
extraction from rivers, but was probably exacerbated by decreasing
precipitation and increasing temperature (Lioubimtseva and Henebry,
2009; Kostianoy and Kosarev, 2010).
24.4.2.2.1. Phenology and growth rates
In humid temperate East Asia, plant observations and satellite
measurements of “greenness” (Normalized Difference Vegetation Index
(NDVI); see Section 4.3.2.2) show a trend to earlier leafing in spring
since the 1980s, averaging 2 days per decade, although details vary
between sites, species, and periods (Table SM24-6; detected with high
confidence and attributed to warming with medium confidence). Earlier
spring flowering and delayed autumn senescence have also been
recorded (Table SM24-6). Trends in semiarid temperate regions were
heterogeneous in space and time (Liu et al., 2013a; Yu, Z. et al., 2013a,b).
Earlier greening has been reported from boreal forests (Delbart et al.,
2008) and from the Hindu-Kush-Himalayan region (Panday and Ghimire,
2012; Shrestha et al., 2012), but with spatial and temporal heterogeneity.
Patterns were also heterogeneous in Central Asia (Kariyeva et al., 2012).
On the Tibetan Plateau, spring growth advanced until the mid-1990s,
but the trend subsequently differs between areas and NDVI data sets
(Yu et al., 2010, 2012; Dong et al., 2013; Jin et al., 2013; Shen et al.,
2013; Yu, Z. et al., 2013a; Zhang, G. et al., 2013; Zhang, L. et al., 2013).
Satellite NDVI for Asia for 1988–2010 shows a general greening trend
(i.e., increasing NDVI, a rough proxy for increasing plant growth), except
where water is limiting (Dorigo et al., 2012). Changes at high latitudes
(
>60°N) show considerable spatial and temporal variability, despite a
consistent warming trend, reflecting water availability and non-climatic
factors (Bi et al., 2013; Jeong et al., 2013). Arctic tundra generally showed
increased greening since 1982, while boreal forests were variable (Goetz
et al., 2011; de Jong et al., 2012; Epstein et al., 2012; Xu et al., 2013).
An overall greening trend for 2000–2011 north of the boreal forest
correlated with increasing summer warmth and ice retreat (Dutrieux et
al., 2012). In China, trends have varied in space and time, reflecting
positive impacts of warming and negative impacts of increasing drought
stress (Peng et al., 2011; Sun et al., 2012; Xu et al., 2012). The steppe
region of northern Kazakhstan showed an overall browning (decreasing
NDVI) trend for 1982–2008, linked to declining precipitation (de Jong et
al., 2012). In Central Asia, where NDVI is most sensitive to precipitation
(Gessner et al., 2013), there was a heterogeneous pattern for 1982–
2009, with an initial greening trend stalled or reversed in some areas
(Mohammat et al., 2013).
Tree-ring data for 800–1989 for temperate East Asia suggests recent
summer temperatures have exceeded those during past warm periods
of similar length, although this difference was not statistically significant
(Cook et al., 2012). Where temperature limits tree growth, growth rates
have increased with warming in recent decades (Duan et al., 2010; Sano
et al., 2010; Shishov and Vaganov, 2010; Borgaonkar et al., 2011; Xu et
al., 2011; Chen et al., 2012a,b,c,d, 2013; Li et al., 2012), while where
drought limits growth, there have been increases (Li et al., 2006; Davi
et al., 2009; Shao et al., 2010; Yang et al., 2010) or decreases (Li et al.,
2007; Dulamsuren et al., 2010a, 2011; Kang et al., 2012; Wu et al., 2012;
Kharuk et al., 2013; Liu et al., 2013b), reflecting decreasing or increasing
water stress (high confidence in detection, medium confidence in
attribution to climate change). In boreal forest, trends varied between
species and locations, despite consistent warming (Lloyd and Bunn,
2007; Goetz et al., 2011).
24.4.2.2.2. Distributions of species and biomes
Changes in species distributions consistent with a response to warming
have been widely reported: upwards in elevation (Soja et al., 2007;
Bickford et al., 2010; Kharuk et al., 2010a,b,e; Moiseev et al., 2010; Chen
et al., 2011; Jump et al., 2012; Grigor’ev et al., 2013; Telwala et al., 2013)
or polewards (Tougou et al., 2009; Ogawa-Onishi and Berry, 2013) (high
confidence in detection, medium confidence in attribution to climate
change). Changes in the distributions of major vegetation types (biomes)
have been reported from the north and high altitudes, where trees are
invading treeless vegetation, and forest understories are being invaded
from adjacent biomes (Kharuk et al., 2006; Soja et al., 2007; Bai et al.,
2011; Singh et al., 2012; Wang and Liu, 2012). In central Siberia, dark
needle conifers (DNCs) and birch have invaded larch-dominated forest
over the last 3 decades (Kharuk et al., 2010c,d; Osawa et al., 2010; Lloyd
et al., 2011). Meanwhile, warming has driven larch stand crown closure
and larch invasion into tundra at a rate of 3 to 10 m yr
–1
in the northern
forest-tundra ecotone (Kharuk et al., 2006). Shrub expansion in arctic
tundra has also been observed (Blok et al., 2011; Myers-Smith et al.,
2011; see Section 28.2.3.1). Soil moisture and light are the main factors
governing the forest-steppe ecotone (Soja et al., 2007; Zeng et al., 2008;
Eichler et al., 2011; Kukavskaya et al., 2013), and Mongolian taiga
forests have responded heterogeneously to recent climate changes, but
1340
Chapter 24 Asia
24
d
eclines in larch growth and regeneration are more widespread than
increases (Dulamsuren et al., 2010a,b).
24.4.2.2.3. Permafrost
Permafrost degradation, including reduced area and increased active
layer thickness, has been reported from parts of Siberia, Central Asia,
and the Tibetan Plateau (high confidence; Romanovsky et al., 2010; Wu
and Zhang, 2010; Zhao et al., 2010; Yang et al., 2013). Most permafrost
observatories in Asian Russia show substantial warming of permafrost
during the last 20 to 30 years (Romanovsky et al., 2008, 2010). Permafrost
formed during the Little Ice Age is thawing at many locations and Late
Holocene permafrost has begun to thaw at some undisturbed locations
in northwest Siberia. Permafrost thawing is most noticeable within the
discontinuous permafrost zone, while continuous permafrost is starting
to thaw in a few places, so the boundary between continuous and
discontinuous permafrost is moving northward (Romanovsky et al.,
2008, 2010).
Thawing permafrost may lead to increasing emissions of greenhouse
gases from decomposition of accumulated organic matter (see Sections
4.3.3.4, 19.6.3.5). In Mongolia, mean annual permafrost temperature
at 10 to 15 m depth increased over the past 10 to 40 years in the
Hovsgol, Hangai, and Hentei Mountain regions. Permafrost warming
during the past 15 to 20 years was greater than during the previous 15
to 20 years (Sharkhuu et al., 2008; Zhao et al., 2010). In the Kazakh part
of the Tien Shan Mountains, permafrost temperature and active layer
thickness have increased since the early 1970s. Significant permafrost
warming also occurred in the eastern Tien Shan Mountains, in the
headwaters of the Urumqi River (Marchenko et al., 2007; Zhao et al.,
2010). Monitoring across the Qinghai-Tibet Plateau over recent decades
has also revealed permafrost degradation caused by warming and other
impacts. Areas of permafrost are shrinking, the active layer depth is
increasing, the lower altitudinal limit is rising, and the seasonal frost
depth is thinning (Li et al., 2008; Wu and Zhang, 2010; Zhao et al., 2010).
In the alpine headwater regions of the Yangtze and Yellow Rivers, rising
temperatures and permafrost degradation have resulted in lower lake
levels, drying swamps, and shrinking grasslands (Cheng and Wu, 2007;
Wang et al., 2011).
24.4.2.3. Projected Impacts
24.4.2.3.1. Phenology and growth rates
Trends toward an earlier spring greening and longer growing season
are expected to continue in humid temperate and boreal forest areas,
although photoperiod or chilling requirements may reduce responses
to warming in some species (Ge et al., 2013; Hadano et al., 2013;
Richardson et al., 2013). Changes in precipitation will be important for
semiarid and arid ecosystems, as may the direct impacts of atmospheric
carbon dioxide (CO
2
) concentrations, making responses harder to predict
(Liancourt et al., 2012; Poulter et al., 2013). The “general flowering” at
multi-year intervals in lowland rainforests in Southeast Asia is triggered
by irregular droughts (Sakai et al., 2006), so changes in drought frequency
or intensity could have large impacts.
24.4.2.3.2. Distributions of species and biomes
Climate change is expected to modify the vegetation distribution across
the region (Tao and Zhang, 2010; Wang, 2013), but responses will be
slowed by limitations on seed dispersal, competition from established
plants, rates of soil development, and habitat fragmentation (high
confidence; Corlett and Westcott, 2013). Rising CO
2
concentrations are
expected to favor increased woody vegetation in semiarid areas
(medium confidence; Higgins and Scheiter, 2012; Donohue et al., 2013;
Poulter et al., 2013; Wang, 2013). In North Asia, rising temperatures are
expected to lead to large changes in the distribution of potential natural
ecosystems (high confidence; Ni, 2011; Tchebakova et al., 2011; Insarov
et al., 2012; Pearson et al., 2013). It is likely that the boreal forest will
expand northward and eastward, and that tundra will decrease,
although differences in models, time periods, and other assumptions
have resulted in widely varying projections for the magnitude of this
change (Woodward and Lomas, 2004; Kaplan and New, 2006; Lucht et
al., 2006; Golubyatnikov and Denisenko, 2007; Sitch et al., 2008;
Korzukhin and Tcelniker, 2010; Tchebakova et al., 2010, 2011; Pearson
et al., 2013). Boreal forest expansion and the continued invasion of the
existing larch-dominated forest by DNCs could lead to larch reaching
the Arctic shore, while the traditional area of larch dominance turns into
mixed forest (Kharuk et al., 2006, 2010c). Both the replacement of
summer-green larch with evergreen conifers and expansion of trees and
shrubs into tundra decrease albedo, causing regional warming and
potentially accelerating vegetation change (Kharuk et al., 2006, 2010d;
McGuire et al., 2007; Pearson et al., 2013). The future direction and rate
of change of steppe vegetation are unclear because of uncertain
precipitation trends (Golubyatnikov and Denisenko, 2007; Tchebakova
et al., 2010). The role of CO
2
fertilization is also potentially important
here (Poulter et al., 2013; see WGI AR5 Box 6.3).
In East Asia, subtropical evergreen forests are projected to expand north
into the deciduous forest and tropical forests to expand along China’s
southern coast (Choi et al., 2011; Wang, 2013), but vegetation change
may lag climate change by decades or centuries (Corlett and Westcott,
2013). On the Tibetan Plateau, projections suggest that alpine vegetation
will be largely replaced by forest and shrubland, with tundra and steppe
retreating to the north (Liang et al., 2012; Wang, 2013). Impacts in
Central and West Asia will depend on changes in precipitation. In
India, a dynamic vegetation model (A2 and B2 scenarios) projected
changes in more than a third of the forest area by 2100, mostly from
deciduous to evergreen forest in response to increasing rainfall,
although fragmentation and other human pressures are expected to
slow these changes (Chaturvedi et al., 2011). By 2100, large areas of
tropical and subtropical lowland Asia are projected to experience
combinations of temperature and rainfall outside the current global range,
under a variety of model projections and emission scenarios (Williams
et al., 2007; Beaumont et al., 2010; García-López and Allué, 2013), but
the potential impacts of these novel conditions on biodiversity are
largely unknown (Corlett, 2011).
In Southeast Asia, projected climate (A2 and B1 scenarios) and vegetation
changes are expected to produce widespread declines in bat species
richness, northward range shifts for many species, and large reductions
in the distributions of most species (Hughes et al., 2012). Projections
for various bird species in Asia under a range of scenarios also suggest
1341
24
Asia Chapter 24
m
ajor impacts on distributions (Menon et al., 2009; Li, R. et al., 2010;
Ko et al., 2012). Projections for butterflies in Thailand (A2 and B2
scenarios) suggest that species richness within protected areas will
decline approximately 30% by 2070–2099 (Klorvuttimontara et al.,
2011). Projections for dominant bamboos in the Qinling Mountains (A2
and B2 scenarios) suggest substantial range reductions by 2100, with
potentially adverse consequences for the giant pandas that eat
them (Tuanmu et al., 2012). Projections for snow leopard habitat in the
Himalayas (B1, A1B, and A2 scenarios) suggest contraction by up to
30% as forests replace open habitats (Forrest et al., 2012).
24.4.2.3.3. Permafrost
In the Northern Hemisphere, a 20 to 90% decrease in permafrost area
and a 50 to 300 cm increase in active layer thickness driven by surface
warming is projected for 2100 by different models and scenarios
(Schaefer et al., 2011). It is likely that permafrost degradation in North
Asia will spread from the southern and low-altitude margins, advancing
northward and upward, but rates of change vary greatly between model
projections (Cheng and Wu, 2007; Riseborough et al., 2008; Romanovsky
et al., 2008; Anisimov, 2009; Eliseev et al., 2009; Nadyozhina et al., 2010;
Schaefer et al., 2011; Wei et al., 2011). Substantial retreat is also expected
on the Qinghai-Tibet Plateau (Cheng and Wu, 2007). Near-surface
permafrost is expected to remain only in Central and Eastern Siberia
and parts of the Qinghai-Tibet Plateau in the late-21st century.
24.4.2.3.4. Inland waters
Climate change impacts on inland waters will interact with dam
construction, pollution, and land use changes (Vörösmarty et al., 2010;
see also Sections 3.3.2, 24.9.1). Increases in water temperature will
impact species- and temperature-dependent processes (Hamilton, 2010;
Dudgeon, 2011, 2012). Coldwater fish will be threatened as rising water
temperatures make much of their current habitat unsuitable (Yu, D. et
al., 2013). Climate change is also expected to change flow regimes in
running waters and consequently impact habitats and species that are
sensitive to droughts and floods (see Box CC-RF). Habitats that depend
on seasonal inundation, including floodplain grasslands and freshwater
swamp forests, will be particularly vulnerable (Maxwell, 2009; Bezuijen,
2011; Arias et al., 2012). Reduced dry season flows are expected to
combine with sea level rise to increase saltwater intrusion in deltas
(Hamilton, 2010; Dudgeon, 2012), although non-climatic impacts will
continue to dominate in most estuaries (Syvitski et al., 2009). For most
Asian lakes, it is difficult to disentangle the impacts of water pollution,
hydro-engineering, and climate change (Battarbee et al., 2012).
24.4.2.4. Vulnerabilities to Key Drivers
Permafrost melting in response to warming is expected to impact
ecosystems across large areas (high confidence; Cheng and Wu, 2007;
Tchebakova et al., 2011). The biodiversity of isolated mountains may also
be particularly vulnerable to warming, because many species already
have small geographical ranges that will shrink further (La Sorte and
Jetz, 2010; Liu et al., 2010; Chou et al., 2011; Noroozi et al., 2011; Peh
e
t al., 2011; Jump et al., 2012; Tanaka, N. et al., 2012; Davydov et al.,
2013). Many freshwater habitats are similarly isolated and their
restricted-range species may be equally vulnerable (Dudgeon, 2012). In
flatter topography, higher velocities of climate change (the speeds that
species need to move to maintain constant climate conditions) increase
the vulnerabilities of species that are unable to keep pace, as a result
of limited dispersal ability, habitat fragmentation, or other non-climatic
constraints (Corlett and Westcott, 2013). In the tropics, temperature
extremes above the present range are a potential threat to organisms
and ecosystems (Corlett, 2011; Jevanandam et al., 2013; Mumby et al.,
2013). For much of interior Asia, increases in drought stress, as a result
of declining rainfall and/or rising temperatures, are the key concern.
Because aridity is projected to increase in the northern Mongolian forest
belt during the 21st century (Sato et al., 2007), larch cover will likely be
reduced (Dulamsuren et al., 2010a). In the boreal forest region, a longer,
warmer growing season will increase vulnerability to fires, although
other human influences may overshadow climate impacts in accessible
areas (Flannigan et al., 2009; Liu et al., 2012; Li et al., 2013; see Section
4.3.3.1.1). If droughts intensify in lowland Southeast Asia, the synergies
between warmth, drought, logging, fragmentation, and fire (Daniau et
al., 2012) and tree mortality (Kumagai and Porporato, 2012; Tan et al.,
2013), possibly acerbated by feedbacks between deforestation, smoke
aerosols, and reduced rainfall (Aragão, 2012; Tosca et al., 2012), could
greatly increase the vulnerability of fragmented forest landscapes (high
confidence).
24.4.2.5. Adaptation Options
Suggested strategies for maximizing the adaptive capacity of ecosystems
include reducing non-climate impacts, maximizing landscape connectivity,
and protecting “refugia where climate change is expected to be less than
the regional mean (Hannah, 2010; Game et al., 2011; Klorvuttimontara
et al., 2011; Murthy et al., 2011; Ren et al., 2011; Shoo et al., 2011;
Mandych et al., 2012). Additional options for inland waters include
operating dams to maintain environmental flows for biodiversity,
protecting catchments, and preserving river floodplains (Vörösmarty et
al., 2010). Habitat restoration may facilitate species movements across
climatic gradients (Klorvuttimontara et al., 2011; Hughes et al., 2012) and
long-distance seed dispersal agents may need protection (McConkey et
al., 2012). Assisted migration of genotypes and species is possible where
movements are constrained by poor dispersal, but risks and benefits
need to be considered carefully (Liu et al., 2010; Olden et al., 2010;
Tchebakova et al., 2011; Dudgeon, 2012; Ishizuka and Goto, 2012;
Corlett and Westcott, 2013). Ex situ conservation can provide backup
for populations and species most at risk from climate change (Chen et
al., 2009).
24.4.3. Coastal Systems and Low-Lying Areas
24.4.3.1. Sub-regional Diversity
Asia’s coastline includes the global range of shore types. Tropical and
subtropical coasts support approximately 45% of the world’s mangrove
forest (Giri et al., 2011) and low-lying areas in equatorial Southeast Asia
support most of the world’s peat swamp forests, as well as other
1342
Chapter 24 Asia
24
f
orested swamp types. Intertidal salt marshes are widespread along
temperate and arctic coasts, while a variety of non-forested wetlands
occur inland. Asia supports approximately 40% of the world’s coral reef
area, mostly in Southeast Asia, with the world’s most diverse reef
communities in the “coral triangle” (Spalding et al., 2001; Burke et al.,
2011). Seagrass beds are widespread and support most of the world’s
seagrass species (Green and Short, 2003). Six of the seven species of
sea turtle are found in the region and five nest on Asian beaches
(Spotila, 2004). Kelp forests and other seaweed beds are important on
temperate coasts (Bolton, 2010; Nagai et al., 2011). Arctic sea ice
supports a specialized community of mammals and other organisms
(see Sections 28.2.3.3-4.).
24.4.3.2. Observed Impacts
Most of Asia’s non-Arctic coastal ecosystems are under such severe
pressure from non-climate impacts that climate impacts are hard to
detect (see Section 5.4.2). Most large deltas in Asia are sinking (as a
result of groundwater withdrawal, floodplain engineering, and trapping
of sediments by dams) much faster than global sea level is rising (Syvitski
et al., 2009). Widespread impacts can be attributed to climate change
only for coral reefs, where the temporal and spatial patterns of bleaching
correlate with higher than normal sea surface temperatures (very high
confidence; Section 5.4.2.4; Box CC-CR). Increased water temperatures
may also explain declines in large seaweed beds in temperate Japan
(Nagai et al., 2011; Section 5.4.2.3). Warming coastal waters have also
been implicated in the northward expansion of tropical and subtropical
macroalgae and toxic phytoplankton (Nagai et al., 2011), fish (Tian et
al., 2012), and tropical corals, including key reef-forming species (Yamano
et al., 2011), over recent decades. The decline of large temperate
seaweeds and expansion of tropical species in southwest Japan has
been linked to rising sea surface temperatures (Tanaka, K. et al., 2012),
and these changes have impacted fish communities (Terazono et al.,
2012).
In Arctic Asia, changes in permafrost and the effects of sea level rise
and sea ice retreat on storm-wave energy have increased erosion (Are
et al., 2008; Razumov, 2010; Handmer et al., 2012). Average erosion
rates range from 0.27 m yr
–1
(Chukchi Sea) to 0.87 m yr
–1
(East Siberian
Sea), with a number of segments in the Laptev and East Siberian Sea
experiencing rates greater than 3 m yr
–1
(Lantuit et al., 2012).
24.4.3.3. Projected Impacts
Marine biodiversity at temperate latitudes is expected to increase as
temperature constraints on warmwater taxa are relaxed (high confidence;
see Section 6.4.1.1), but biodiversity in tropical regions may fall if, as
evidence suggests, tropical species are already near their thermal maxima
(medium confidence; Cheung et al., 2009, 2010; Nguyen et al., 2011).
Individual fish species are projected to shift their ranges northward in
response to rising sea surface temperatures (Tseng et al., 2011; Okunishi
et al., 2012; Tian et al., 2012). The combined effects of changes in
distribution, abundance, and physiology may reduce the body size of
marine fishes, particularly in the tropics and intermediate latitudes
(Cheung et al., 2013).
C
ontinuation of current trends in sea surface temperatures and ocean
acidification would result in large declines in coral-dominated reefs by
mid-century (high confidence; Burke et al., 2011; Hoegh-Guldberg, 2011;
see Section 5.4.2.4; Box CC-CR). Warming would permit the expansion
of coral habitats to the north but acidification is expected to limit this
(Yara et al., 2012). Acidification is also expected to have negative
impacts on other calcified marine organisms (algae, molluscs, larval
echinoderms), while impacts on non-calcified species are unclear
(Branch et al., 2013; Kroeker et al., 2013; see Box CC-OA). On rocky
shores, warming and acidification are expected to lead to range shifts
and changes in biodiversity (see Section 5.4.2.2).
Future rates of sea level rise are expected to exceed those of recent
decades (see WGI AR5 Section 13.5.1), increasing coastal flooding,
erosion, and saltwater intrusion into surface and groundwaters. In the
absence of other impacts, coral reefs may grow fast enough to keep up
with rising sea levels (Brown et al., 2011; Villanoy et al., 2012; see
Section 5.4.2.4), but beaches may erode and mangroves, salt marshes,
and seagrass beds will decline, unless they receive sufficient fresh
sediment to keep pace or they can move inland (Gilman et al., 2008;
Bezuijen, 2011; Kintisch, 2013; see Section 5.3.2.3). Loucks et al. (2010)
predict a 96% decline in tiger habitat in Bangladesh’s Sunderbans
mangroves with a 28 cm sea level rise if sedimentation does not increase
surface elevations. Rising winter temperatures are expected to result in
poleward expansion of mangrove ecosystems (see Section 5.4.2.3).
Coastal freshwater wetlands may be vulnerable to saltwater intrusion
with rising sea levels, but in most river deltas local subsidence for non-
climatic reasons will be more important (Syvitski et al., 2009). Current
trends in cyclone frequency and intensity are unclear (Section 24.3.2;
Box CC-TC), but a combination of cyclone intensification and sea level
rise could increase coastal flooding (Knutson et al., 2010) and losses of
coral reefs and mangrove forests would exacerbate wave damage
(Gedan et al., 2011; Villanoy et al., 2012).
In the Asian Arctic, rates of coastal erosion are expected to increase
as a result of interactions between rising sea levels and changes in
permafrost and the length of the ice-free season (medium evidence;
high agreement; Pavlidis et al., 2007; Lantuit et al., 2012). The largest
changes are expected for coasts composed of loose permafrost rocks
and therefore subject to intensive thermal abrasion. If sea level rises
by 0.5 m over this century, modeling studies predict that the rate of
recession will increase 1.5- to 2.6-fold for the coasts of the Laptev Sea,
East Siberian Sea, and West Yamal in the Kara Sea, compared to the
rate observed in the first years of the 21st century.
24.4.3.4. Vulnerabilities to Key Drivers
Offshore marine systems are most vulnerable to rising water temperatures
and ocean acidification, particularly for calcifying organisms such as
corals. Sea level rise will be the key issue for many coastal areas,
particularly if combined with changes in cyclone frequency or intensity,
or, in Arctic Asia, with a lengthening open-water season. The expected
continuing decline in the extent of sea ice in the Arctic may threaten
the survival of some ice-associated organisms (see Section 28.2.2.1),
with expanded human activities in previously inaccessible areas an
additional concern (Post et al., 2013).
1343
24
Asia Chapter 24
24.4.3.5. Adaptation Options
The connectivity of marine habitats and dispersal abilities of marine
organisms increase the capacity for autonomous (spontaneous) adaptation
in coastal systems (Cheung et al., 2009). Creating marine protected
areas where sea surface temperatures are projected to change least
may increase their future resilience (Levy and Ban, 2013). For coral reefs,
potential indicators of future resilience include later projected onset of
annual bleaching conditions (van Hooidonk et al., 2013), past temperature
variability, the abundance of heat-tolerant coral species, coral recruitment
rates, connectivity, and macroalgae abundance (McClanahan et al.,
2012). Similar strategies may help identify reefs that are more resilient
to acidification (McLeod et al., 2013). Hard coastal defenses, such as
sea walls, protect settlements at the cost of preventing adjustments
by mangroves, salt marshes, and seagrass beds to rising sea levels.
Landward buffer zones that provide an opportunity for future inland
migration could mitigate this problem (Tobey et al., 2010). More
generally, maintaining or restoring natural shorelines where possible is
expected to provide coastal protection and other benefits (Tobey et al.,
2010; Crooks et al., 2011). Projected increases in the navigability of the
Arctic Ocean because of declining sea ice suggest the need for a revision
of environmental regulations to minimize the risk of marine pollution
(Smith and Stephenson, 2013).
24.4.4. Food Production Systems and Food Security
It is projected that climate change will affect food security by the middle
of the 21st century, with the largest numbers of food-insecure people
located in South Asia (see Chapter 7).
24.4.4.1. Sub-regional Diversity
WGII AR4 Section 10.4.1.1 pointed out that there will be regional
differences within Asia in the impacts of climate change on food
production. Research since then has validated this divergence and new
data are available especially for West and Central Asia (see Tables
SM24-4, SM24-5). In WGII AR4 Section 10.4.1, climate change was
projected to lead mainly to reductions in crop yield. New research shows
there will also be gains for specific regions and crops in given areas.
Thus, the current assessment encompasses an enormous variability,
depending on the regions and the crops grown.
24.4.4.2. Observed Impacts
There are very limited data globally for observed impacts of climate
change on food production systems (see Chapter 7) and this is true also
for Asia. In Jordan, it was reported that the total production and average
yield for wheat and barley were lowest in 1999 for the period 1996–
2006 (Al-Bakri et al., 2010), which could be explained by the low rainfall
during that year, which was 30% of the average (high confidence in
detection, low confidence in attribution). In China, rice yield responses
to recent climate change at experimental stations were assessed for
the period 1981–2005 (Zhang et al., 2010). In some places, yields were
positively correlated with temperature when they were also positively
r
elated with solar radiation. However, in other places, lower yield with
higher temperature was accompanied by a positive correlation between
yield and rainfall (high confidence in detection, high confidence in
attribution). In Japan, where mean air temperature rose by about 1ºC
over the 20th century, effects of recent warming include phenological
changes in many crops, increases in fruit coloring disorders and incidences
of chalky rice kernels, reductions in yields of wheat, barley, vegetables,
flowers, milk, and eggs, and alterations in the type of disease and pest
(high confidence in detection, high confidence in attribution; Sugiura et
al., 2012).
24.4.4.3. Projected Impacts
24.4.4.3.1. Production
WGII AR4 Section 10.4.1.1 mainly dealt with cereal crops (rice, wheat,
corn). Since then, impacts of climate change have been modeled for
additional cereal crops and sub-regions. It is very likely that climate
change effects on crop production in Asia will be variable, negative for
specific regions and crops in given areas and positive for other regions
and crops (medium evidence, high agreement). It is also likely that an
elevated CO
2
concentration in the atmosphere will be beneficial to most
crops (medium evidence, high agreement).
In semiarid areas, rainfed agriculture is sensitive to climate change both
positively and negatively (Ratnakumar et al., 2011). In the mountainous
Swat and Chitral districts of Pakistan (average altitudes 960 and 1500 m
above sea level, respectively), there were mixed results as well (Hussain
and Mudasser, 2007). Projected temperature increases of 1.5°C and 3°C
would lead to wheat yield declines (by 7% and 24%, respectively) in
Swat district but to increases (by 14% and 23%) in Chitral district. In
India, climate change impacts on sorghum were analyzed using the
InfoCrop-SORGHUM simulation model (Srivastava et al., 2010). A
changing climate was projected to reduce monsoon sorghum grain yield
by 2 to 14% by 2020, with worsening yields by 2050 and 2080. In the
Indo-Gangetic Plains, a large reduction in wheat yields is projected (see
Section 24.4.4.3.2), unless appropriate cultivars and crop management
practices are adopted (Ortiz et al., 2008). A systematic review and meta-
analysis of data in 52 original publications projected mean changes in
yield by the 2050s across South Asia of 16% for maize and 11% for
sorghum (Knox et al., 2012). No mean change in yield was projected
for rice.
In China, modeling studies of the impacts of climate change on crop
productivity have had mixed results. Rice is the most important staple
food in Asia. Studies show that climate change will alter productivity
in China but not always negatively. For example, an ensemble-based
probabilistic projection shows rice yield in eastern China would change
on average by 7.5 to 17.5% (–10.4 to 3.0%), 0.0 to 25.0% (–26.7 to
2.1%), and –10.0 to 25.0% (–39.2 to –6.4%) during the 2020s, 2050s,
and 2080s, respectively, in response to climate change, with (without)
consideration of CO
2
fertilization effects, using all 10 combinations of
two emission scenarios (A1FI and B1) and five GCMs (Hadley Centre
climate prediction model 3 (HadCM3), Parallel Climate Model (PCM),
CGCM2, Commonwealth Scientific and Industrial Research Organisation
2 (CSIRO2), and European Centre for Medium Range Weather Forecasts
1344
Chapter 24 Asia
24
and Hamburg 4 (ECHAM4)) relative to 1961–1990 levels (Tao and Zhang,
2013a). With rising temperatures, the process of rice development
accelerates and reduces the duration for growth. Wassmann et al.
(2009a,b) concluded that, in terms of risks of increasing heat stress,
there are parts of Asia where current temperatures are already
approaching critical levels during the susceptible stages of the rice
plant. These include Pakistan/North India (October), South India (April/
August), East India/Bangladesh (March-June), Myanmar/Thailand/Laos/
Cambodia (March-June), Vietnam (April/August), Philippines (April/June),
Indonesia (August), and China (July/August).
There have also been simulation studies for other crops in China. In
the Huang-Hai Plain, China’s most productive wheat growing region,
modeling indicated that winter wheat yields would increase on average
by 0.2 Mg ha
–1
in 2015–2045 and by 0.8 Mg ha
–1
in 2070–2099, due
to warmer nighttime temperatures and higher precipitation, under A2
and B2 scenarios using the HadCM3 model (Thomson et al., 2006). In
the North China Plain, an ensemble-based probabilistic projection
projected that maize yield will change by –9.7 to –9.1%, 19.0 to
–15.7%, and –25.5 to –24.7%, during 2020s, 2050s, and 2080s as a
percentage of 1961–1990 yields (Tao et al., 2009). In contrast, winter
wheat yields could increase with high probability in future due to
climate change (Tao and Zhang, 2013b).
It should be noted that crop physiology simulation models may
overstate the impact of CO
2
fertilization. Free Atmosphere Carbon
Exchange (FACE) experiments show that measurable CO
2
fertilization
effects are typically less than modeled results (see Section 7.3).
Extreme weather events are also expected to negatively affect agricultural
crop production (IPCC, 2012). For example, extreme temperatures could
lower yields of rice (Mohammed and Tarpley, 2009; Tian et al., 2010).
With higher precipitation, flooding could also lead to lower crop
production (see SREX Chapter 4).
24.4.4.3.2. Farming systems and crop areas
Since the release of the AR4 (see WGII AR4 Section 10.4.1.2), more
information is available on the impacts of climate change on farming
systems and cropping areas in more countries in Asia and especially in
Central Asia. Recent studies validate the likely northward shifts of crop
production with current croplands under threat from the impacts of
climate change (medium evidence, medium agreement). Cooler regions
are likely to benefit as warmer temperatures increase arable areas
(medium evidence, high agreement).
Central Asia is expected to become warmer in the coming decades
and increasingly arid, especially in the western parts of Turkmenistan,
Uzbekistan, and Kazakhstan (Lioubimtseva and Henebry, 2009). Some
parts of the region could be winners (cereal production in northern and
eastern Kazakhstan could benefit from the longer growing <