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The answer to Question 5 is taken from:
IPCC  TAR
SPM of WG II
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5.1.1. What will be the effects on and vulnerability of hydrology
and water resources?
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"The effect of climate
change on streamflow and groundwater recharge varies regionally
and between climate scenarios, largely following projected changes
in precipitation. A consistent projection across most climate change
scenarios is for increases in annual mean streamflow in high latitudes
and southeast Asia, and decreases in central Asia, the area around
the Mediterranean, southern Africa, and Australia (medium confidence6)
(see Figure
SPM-3); the amount of change, however, varies between scenarios.
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Changes
in Water Runoff
Figure SPM-3
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For other areas, including mid-latitudes, there
is no strong consistency in projections of streamflow, partly because
of differences in projected rainfall and partly because of differences
in projected evaporation, which can offset rainfall increases. The
retreat of most glaciers is projected to accelerate, and many small
glaciers may disappear (high confidence6).
In general, the projected changes in average annual runoff are less
robust than impacts based solely on temperature change because precipitation
changes vary more between scenarios. At the catchment scale, the
effect of a given change in climate varies with physical properties
and vegetation of catchments, and may be in addition to land-cover
changes. [4.1]
Links...
Approximately 1.7 billion people, one-third of the
world's population, presently live in countries that are water-stressed
(defined as using more than 20% of their renewable water supply,
a commonly used indicator of water stress). This number is projected
to increase to around 5 billion by 2025, depending on the rate of
population growth. The projected climate
change could further decrease the streamflow and groundwater
recharge in many of these water-stressed countries—for example
in central Asia, southern Africa, and countries around the Mediterranean
Sea—but may increase it in some others. [4.1;
see also 5.1.1,
5.2.3,
5.3.1,
5.4.1,
5.5.1,
5.6.2,
and 5.8.4
for regional-scale information] Links...
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Demand for water is generally increasing due to
population growth and economic development, but is falling in some
countries because of increased efficiency of use. Climate
change is unlikely to have a big effect on municipal and industrial
water demands in general, but may substantially affect irrigation
withdrawals, which depend on how increases in evaporation are offset
or exaggerated by changes in precipitation. Higher temperatures,
hence higher crop evaporative demand, mean that the general tendency
would be towards an increase in irrigation demands. [4.1]
Links...
Flood magnitude and frequency could increase in
many regions as a consequence of increased frequency of heavy precipitation
events, which can increase runoff in most areas as well as groundwater
recharge in some floodplains. Land-use change could exacerbate such
events. Streamflow during seasonal low flow periods would decrease
in many areas due to greater evaporation; changes in precipitation
may exacerbate or offset the effects of increased evaporation. The
projected climate
change would degrade water quality through higher water temperatures
and increased pollutant load from runoff and overflows of waste
facilities. Quality would be degraded further where flows decrease,
but increases in flows may mitigate to a certain extent some degradations
in water quality by increasing dilution. Where snowfall is currently
an important component of the water balance, a greater proportion
of winter precipitation may fall as rain, and this can result in
a more intense peak streamflow which in addition would move from
spring to winter. [4.1]
Links...
The greatest vulnerabilities are likely to be in
unmanaged water systems and systems that are currently stressed
or poorly and unsustainably managed due to policies that discourage
efficient water use and protection of water quality, inadequate
watershed management, failure to manage variable water supply and
demand, or lack of sound professional guidance. In unmanaged systems
there are few or no structures in place to buffer the effects of
hydrologic variability on water quality and supply. In unsustainably
managed systems, water and land uses can add stresses that heighten
vulnerability to climate
change. [4.1]
Links...
Water resource management techniques, particularly
those of integrated water resource management, can be applied to
adapt to hydrologic effects of climate
change, and to additional uncertainty, so as to lessen vulnerabilities.
Currently, supply-side approaches (e.g., increasing flood defenses,
building weirs, utilizing water storage areas, including natural
systems, improving infrastructure for water collection and distribution)
are more widely used than demand-side approaches (which alter the
exposure
to stress); the latter is the focus of increasing attention. However,
the capacity to implement effective management responses is unevenly
distributed around the world and is low in many transition and developing
countries" [4.1]
Links...
Source
& © :
IPCC
TAR SPM of WG II page 9 & 10
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5.1.2. What will be the effects on and vulnerability of agriculture
and food security?
"Based on experimental research, crop yield
responses to climate
change vary widely, depending upon species and cultivar; soil
properties; pests, and pathogens; the direct effects of carbon dioxide
(CO2) on plants; and interactions
between CO2, air temperature, water
stress, mineral nutrition, air quality, and adaptive responses.
Even though increased CO2 concentration
can stimulate crop growth and yield, that benefit may not always
overcome the adverse effects of excessive heat and drought (medium
confidence6).
These advances, along with advances in research on agricultural
adaptation, have been incorporated since the Second Assessment Report
(SAR) into models used to assess the effects of climate change on
crop yields, food supply, farm incomes, and prices. [4.2]
Links...
Costs will be involved in coping with climate-induced
yield losses and adaptation of livestock production systems. These
agronomic and husbandry adaptation options could include, for example,
adjustments to planting dates, fertilization rates, irrigation applications,
cultivar traits, and selection of animal species. [4.2]
Links...
When autonomous agronomic adaptation is included,
crop modeling assessments indicate, with medium to low confidence6,
that climate
change will lead to generally positive responses at less than
a few °C warming and generally negative responses for more than
a few °C in mid-latitude crop yields. Similar assessments indicate
that yields of some crops in tropical locations would decrease generally
with even minimal increases in temperature, because such crops are
near their maximum temperature tolerance and dryland/rainfed agriculture
predominates. Where there is also a large decrease in rainfall,
tropical crop yields would be even more adversely affected. With
autonomous agronomic adaptation, crop yields in the tropics tend
to be less adversely affected by climate change than without adaptation,
but they still tend to remain below levels estimated with current
climate. [4.2]
Links...
Most global and regional economic studies not incorporating
climate
change indicate that the downward trend in global real commodity
prices in the 20th century is likely to continue into the 21st,
although confidence in these predictions decreases farther into
the future. Economic modeling assessments indicate that impacts
of climate change on agricultural production and prices are estimated
to result in small percentage changes in global income (low confidence6),
with larger increases in more developed regions and smaller increases
or declines in developing regions. Improved confidence in this finding
depends on further research into the sensitivity of economic modeling
assessments to their base assumptions. [4.2
and Box
5-5] Links...
Most studies indicate that global mean annual temperature
increases of a few °C or greater would prompt food prices to
increase due to a slowing in the expansion of global food supply
relative to growth in global food demand (established, but incomplete
6).
At lesser amounts of warming than a few °C, economic models
do not clearly distinguish the climate
change signal from other sources of change based on those studies
included in this assessment. Some recent aggregated studies have
estimated economic impacts on vulnerable populations such as smallholder
producers and poor urban consumers. These studies find that climate
change would lower incomes of the vulnerable populations and increase
the absolute number of people at risk of hunger, though this is
uncertain and requires further research. It is established, though
incompletely, that climate change, mainly through increased extremes
and temporal/ spatial shifts, will worsen food security in Africa."
[4.2]
Links...
Source
& © :
IPCC
TAR SPM of WG II pages 9-11
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5.1.3. What will be the effects on and vulnerability of terrestrial
and freshwater ecosystems?
"Vegetation modeling studies continue to show
the potential for significant disruption of ecosystems
under climate
change (high confidence6).
Migration of ecosystems or biomes as discrete units is unlikely
to occur; instead at a given site, species composition and dominance
will change. The results of these changes will lag behind the changes
in climate by years to decades to centuries (high confidence6).
[4.3]
Links...
Distributions, population sizes, population density,
and behavior of wildlife have been, and will continue to be, affected
directly by changes in global or regional climate and indirectly
through changes in vegetation. Climate
change will lead to poleward movement of the boundaries of freshwater
fish distributions along with loss of habitat for cold- and cool-water
fishes and gain in habitat for warm-water fishes (high confidence6).
Many species and populations are already at high risk, and are expected
to be placed at greater risk by the synergy between climate change
rendering portions of current habitat unsuitable for many species,
and land-use change fragmenting habitats and raising obstacles to
species migration. Without appropriate management, these pressures
will cause some species currently classified as "critically endangered"
to become extinct and the majority of those labeled "endangered
or vulnerable" to become rarer, and thereby closer to extinction,
in the 21st century (high confidence6).
[4.3]
Links...
Possible adaptation methods to reduce risks to species
could include: 1) establishment of refuges, parks, and reserves
with corridors to allow migration of species, and 2) use of captive
breeding and translocation. However, these options may have limitations
due to costs. [4.3]
Links...
Terrestrial ecosystems
appear to be storing increasing amounts of carbon. At the time of
the SAR, this was largely attributed to increasing plant productivity
because of the interaction between elevated CO2
concentration, increasing temperatures, and soil moisture changes.
Recent results confirm that productivity gains are occurring but
suggest that they are smaller under field conditions than indicated
by plant-pot experiments (medium confidence6).
Hence, the terrestrial uptake
may be due more to change in uses and management of land than to
the direct effects of elevated CO2
and climate. The degree to which terrestrial ecosystems continue
to be net
sinks for carbon is uncertain due to the complex interactions
between the factors mentioned above (e.g., arctic terrestrial ecosystems
and wetlands may act as both sources and sinks) (medium confidence6).
[4.3]
Links...
Contrary to the SAR, global timber market studies
that include adaptations through land and product management, even
without forestry projects that increase the capture and storage
of carbon, suggest that a small amount of climate
change would increase global timber supply and enhance existing
market trends towards rising market share in developing countries
(medium confidence6).
Consumers may benefit from lower timber prices while producers may
gain or lose depending on regional changes in timber productivity
and potential dieback effects." [4.3]
Links...
Source
& © :
IPCC
TAR SPM of WG II page 11
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5.1.4. What will be the effects on and vulnerability of coastal
zones and marine ecosystems?
"Large-scale impacts of climate
change on oceans are expected to include increases in sea surface
temperature and mean global sea level, decreases in sea-ice cover,
and changes in salinity, wave conditions, and ocean circulation.
The oceans are an integral and responsive component of the climate
system with important physical and biogeochemical feedbacks
to climate. Many marine ecosystems
are sensitive to climate change. Climate trends and variability
as reflected in multiyear climate-ocean regimes (e.g., Pacific Decadal
Oscillation) and switches from one regime to another are now recognized
to strongly affect fish abundance and population dynamics, with
significant impacts on fish-dependent human societies. [4.4]
Links...
Many coastal areas will experience increased levels
of flooding, accelerated erosion, loss of wetlands and mangroves,
and seawater intrusion into freshwater sources as a result of climate
change. The extent and severity of storm impacts, including
storm-surge floods and shore erosion, will increase as a result
of climate change including sea-level rise. High-latitude coasts
will experience added impacts related to higher wave energy and
permafrost degradation. Changes in relative sea level will vary
locally due to uplift and subsidence caused by other factors. [4.4]
Links...
Impacts on highly diverse and productive coastal
ecosystems such as coral reefs, atolls and reef islands, salt marshes
and mangrove forests will depend upon the rate of sea-level rise
relative to growth rates and sediment supply, space for and obstacles
to horizontal migration, changes in the climate-ocean environment
such as sea surface temperatures and storminess, and pressures from
human activities in coastal zones. Episodes of coral bleaching over
the past 20 years have been associated with several causes, including
increased ocean temperatures. Future sea surface warming would increase
stress on coral reefs and result in increased frequency of marine
diseases (high confidence6).
[4.4]
Links...
Assessments of adaptation strategies for coastal
zones have shifted emphasis away from hard protection structures
of shorelines (e.g., seawalls, groins) toward soft protection measures
(e.g., beach nourishment), managed retreat, and enhanced resilience
of biophysical and socioeconomic systems in coastal regions. Adaptation
options for coastal and marine management are most effective when
incorporated with policies in other areas, such as disaster mitigation
plans and land-use plans." [4.4]
Links...
Source
& © :
IPCC
TAR SPM of WG II pages 11-12
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5.2.1. What will be the effects on and vulnerability of human
health?
"The impacts of short-term weather events on
human health have been further elucidated since the SAR, particularly
in relation to periods of thermal stress, the modulation of air
pollution impacts, the impacts of storms and floods, and the influences
of seasonal and interannual climatic variability on infectious diseases.
There has been increased understanding of the determinants of population
vulnerability to adverse health impacts and the possibilities for
adaptive responses. [4.7]
Links...
Many vector-, food-, and water-borne infectious
diseases are known to be sensitive to changes in climatic conditions.
From results of most predictive model studies, there is medium to
high confidence6
that, under climate
change scenarios, there would be a net increase in the geographic
range of potential transmission of malaria and dengue-two vector-borne
infections each of which currently impinge on 40-50% of the world
population10.Within
their present ranges, these and many other infectious diseases would
tend to increase in incidence and seasonality-although regional
decreases would occur in some infectious diseases. In all cases,
however, actual disease occurrence is strongly influenced by local
environmental conditions, socioeconomic circumstances, and public
health infrastructure. [4.7]
Links...
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Projected climate
change will be accompanied by an increase in heat waves, often
exacerbated by increased humidity and urban air pollution, which
would cause an increase in heat-related deaths and illness episodes.
The evidence indicates that the impact would be greatest in urban
populations, affecting particularly the elderly, sick, and those
without access to air-conditioning (high confidence6).
Limited evidence indicates that in some temperate countries reduced
winter deaths would outnumber increased summer deaths (medium confidence6);
yet, published research has been largely confined to populations
in developed countries, thus precluding a generalized comparison
of changes in summer and winter mortality. [3.5
and 4.7]
Links...
Extensive experience makes clear that any increase
in flooding will increase the risk of drowning, diarrhoeal and respiratory
diseases, and, in developing countries, hunger and malnutrition
(high confidence6).
If cyclones were to increase regionally, devastating impacts would
often occur, particularly in densely settled populations with inadequate
resources. A reduction in crop yields and food production because
of climate
change in some regions, particularly in the tropics, will predispose
food-insecure populations to malnutrition, leading to impaired child
development and decreased adult activity. Socioeconomic disruptions
could occur in some regions, impairing both livelihoods and health.
[3.5,
4.1,
4.2,
4.5,
and 4.7]
Links...
For each anticipated adverse health impact there
is a range of social, institutional, technological, and behavioral
adaptation options to lessen that impact. Adaptations could, for
example, encompass strengthening of the public health infrastructure,
health-oriented management of the environment (including air and
water quality, food safety, urban and housing design, and surface
water management), and the provision of appropriate medical care
facilities. Overall, the adverse health impacts of climate
change will be greatest in vulnerable lower income populations,
predominantly within tropical/subtropical countries. Adaptive policies
would, in general, reduce these impacts." [4.7]
Links...
Source
& © :
IPCC
TAR SPM of WG II page 12
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5.2.2. What will be the effects on and vulnerability of human
settlements, energy, and industry?
"A growing and increasingly quantitative literature
shows that human settlements are affected by climate
change in one of three major ways:
- The economic sectors that support the settlement
are affected because of changes in resource productivity or changes
in market demand for the goods and services produced there. [4.5]
Links...
- Some aspects of physical infrastructure (including
energy transmission and distribution systems), buildings, urban
services (including transportation systems), and specific industries
(such as agroindustry, tourism, and construction) may be directly
affected. [4.5]
Links...
- Populations may be directly affected through
extreme weather, changes in health status, or migration. The problems
are somewhat different in the largest (<1 million) and mid-
to small-sized population centers. [4.5]
Links...
The most widespread direct risk to human settlements
from climate
change is flooding and landslides, driven by projected increases
in rainfall intensity and, in coastal areas, sea-level rise. Riverine
and coastal settlements are particularly at risk (high confidence6),
but urban flooding could be a problem anywhere that storm drains,
water supply, and waste management systems have inadequate capacity.
In such areas, squatter and other informal urban settlements with
high population density, poor shelter, little or no access to resources
such as safe water and public health services, and low adaptive
capacity are highly vulnerable. Human settlements currently
experience other significant environmental problems which could
be exacerbated under higher temperature/increased precipitation
regimes, including water and energy resources and infrastructure,
waste treatment, and transportation. [4.5]
Links...
Rapid urbanization in low-lying coastal areas of
both the developing and developed world is greatly increasing population
densities and the value of human-made assets exposed to coastal
climatic extremes such as tropical cyclones. Model-based projections
of the mean annual number of people who would be flooded by coastal
storm surges increase several fold (by 75 to 200 million people
depending on adaptive responses) for mid-range scenarios of a 40-cm
sea-level rise by the 2080s relative to scenarios with no sea-level
rise. Potential damages to infrastructure in coastal areas from
sea-level rise have been projected to be tens of billions US$ for
individual countries—for example, Egypt, Poland, and Vietnam.
[4.5]
Links...
Settlements with little economic diversification
and where a high percentage of incomes derive from climate-sensitive
primary resource industries (agriculture, forestry, and fisheries)
are more vulnerable than more diversified settlements (high confidence6).
In developed areas of the Arctic, and where the permafrost is ice-rich,
special attention will be required to mitigate the detrimental impacts
of thawing, such as severe damage to buildings and transport infrastructure
(very high confidence6).
Industrial, transportation, and commercial infrastructure is generally
vulnerable to the same hazards as settlement infrastructure. Energy
demand is expected to increase for space cooling and decrease for
space heating, but the net effect is scenario- and location-dependent.
Some energy production and distribution systems may experience adverse
impacts that would reduce supplies or system reliability while other
energy systems may benefit.
[4.5
and 5.7]
Links...
Possible adaptation options involve the planning
of settlements and their infrastructure, placement of industrial
facilities, and making similar long-lived decisions in a manner
to reduce the adverse effects of events that are of low (but increasing)
probability and high (and perhaps rising) consequences." [4.5]
Links...
Source
& © :
IPCC
TAR SPM of WG II pages 12-13
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5.2.3. What will be the effects on and vulnerability of insurance
and other financial services?
"The costs of ordinary and extreme weather
events have increased rapidly in recent decades. Global economic
losses from catastrophic events increased 10.3-fold from 3.9 billion
US$ yr-1 in the 1950s to
40 billion US$ yr-1 in
the 1990s (all in 1999US$, unadjusted for purchasing power parity),
with approximately one-quarter of the losses occurring in developing
countries. The insured portion of these losses rose from a negligible
level to 9.2 billion US$ yr-1
during the same period. Total costs are a factor of two larger when
losses from smaller, non-catastrophic weather-related events are
included. As a measure of increasing insurance industry vulnerability,
the ratio of global property/casual insurance premiums to weather
related losses fell by a factor of three between 1985 and 1999.
[4.6]
Links...
The costs of weather events have risen rapidly despite
significant and increasing efforts at fortifying infrastructure
and enhancing disaster preparedness. Part of the observed upward
trend in disaster losses over the past 50 years is linked to socioeconomic
factors, such as population growth, increased wealth, and urbanization
in vulnerable areas, and part is linked to climatic factors such
as the observed changes in precipitation and flooding events. Precise
attribution is complex and there are differences in the balance
of these two causes by region and type of event. [4.6]
Links...
Climate
change and anticipated changes in weather-related events perceived
to be linked to climate change would increase actuarial uncertainty
in risk assessment (high confidence6).
Such developments would place upward pressure on insurance premiums
and/or could lead to certain risks being reclassified as uninsurable
with subsequent withdrawal of coverage. Such changes would trigger
increased insurance costs, slow the expansion of financial services
into developing countries, reduce the availability of insurance
for spreading risk, and increase the demand for government-funded
compensation following natural disasters. In the event of such changes,
the relative roles of public and private entities in providing insurance
and risk management resources can be expected to change. [4.6]
Links...
The financial services sector as a whole is expected
to be able to cope with the impacts of climate
change, although the historic record demonstrates that low-probability
high-impact events or multiple closely spaced events severely affect
parts of the sector, especially if adaptive capacity happens to
be simultaneously depleted by non-climate factors (e.g., adverse
financial market conditions). The property/casualty insurance and
reinsurance segments and small specialized or undiversified companies
have exhibited greater sensitivity, including reduced profitability
and bankruptcy triggered by weather-related events. [4.6]
Links...
Adaptation to climate
change presents complex challenges, but also opportunities,
to the sector. Regulatory involvement in pricing, tax treatment
of reserves, and the (in)ability of firms to withdraw from at-risk
markets are examples of factors that influence the resilience of
the sector. Public- and private-sector actors also support adaptation
by promoting disaster preparedness, loss-prevention programs, building
codes, and improved land-use planning. However, in some cases, public
insurance and relief programs have inadvertently fostered complacency
and maladaptation by inducing development in at-risk areas such
as U.S. flood plains and coastal zones. [4.6]
Links...
The effects of climate
change are expected to be greatest in the developing world,
especially in countries reliant on primary production as a major
source of income. Some countries experience impacts on their GDP
as a consequence of natural disasters, with damages as high as half
of GDP in one case. Equity issues and development constraints would
arise if weather-related risks become uninsurable, prices increase,
or availability becomes limited. Conversely, more extensive access
to insurance and more widespread introduction of micro-financing
schemes and development banking would increase the ability of developing
countries to adapt to climate change." [4.6]
Links...
Source
& © :
IPCC
TAR SPM of WG II pages 13-14
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5.3. How does climate change vulnerability vary across regions?
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"The vulnerability of human populations and
natural systems to climate
change differs substantially across regions and across populations
within regions. Regional differences in baseline climate and expected
climate change give rise to different exposures to climate stimuli
across regions. The natural and social systems of different regions
have varied characteristics, resources, and institutions, and are
subject to varied pressures that give rise to differences in sensitivity
and adaptive
capacity. From these differences emerge different key concerns
for each of the major regions of the world. Even within regions
however, impacts, adaptive capacity, and vulnerability will vary.
[5]
Links...
In light of the above, all regions are likely to
experience some adverse effects of climate
change. Table
SPM-2 presents in a highly summarized fashion some of the key
concerns for the different regions. Some regions are particularly
vulnerable because of their physical exposure to climate change
hazards and/or their limited adaptive capacity. Most less-developed
regions are especially vulnerable because a larger share of their
economies are in climate-sensitive sectors and their adaptive capacity
is low due to low levels of human, financial, and natural resources,
as well as limited institutional and technological capability. For
example, small island states and low-lying coastal areas are particularly
vulnerable to increases in sea level and storms, and most of them
have limited capabilities for adaptation. Climate change impacts
in polar regions are expected to be large and rapid, including reduction
in sea-ice extent and thickness and degradation of permafrost. Adverse
changes in seasonal river flows, floods and droughts, food security,
fisheries, health effects, and loss of biodiversity are among the
major regional vulnerabilities and concerns of Africa, Latin America,
and Asia where adaptation opportunities are generally low. Even
in regions with higher adaptive capacity, such as North America
and Australia and New Zealand, there are vulnerable communities,
such as indigenous peoples, and the possibility of adaptation of
ecosystems
is very limited. In Europe, vulnerability is significantly greater
in the south and in the Arctic than elsewhere in the region."
[5]
Links...
Source
& © :
IPCC
TAR SPM of WG II pages 14-16
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