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| Berichte über den Klimawandel - Globale Berichte |
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| Intergovernmental Panel on Climate Change - Fourth Assessment Report |
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| Climate Change 2007 |
| Climate Change Impacts, Adaptation and Vulnerability |
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| Impacts on the Regions in the World |
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More
specific information is now available across the regions of the world concerning
the nature of future impacts, including for some places not covered in
previous assessments.
| Africa |
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By 2020, between 75 and 250 million people are projected to be exposed to an increase of water stress due to climate change. If coupled with increased demand, this will adversely affect livelihoods and exacerbate water-related problems.
Agricultural production, including access to food, in many African countries and regions is projected to be severely compromised by climate variability and change. The area suitable for agriculture, the length of growing seasons and yield potential, particularly along the margins of semi-arid and arid areas, are expected to decrease. This would further adversely affect food security and exacerbate malnutrition in the continent. In some countries, yields from rain-fed agriculture could be reduced by up to 50% by 2020.
Local food supplies are projected to be negatively affected by decreasing fisheries resources in large lakes due to rising water temperatures, which may be exacerbated by continued over-fishing.
Towards the end of the 21st century, projected sea-level rise will affect low-lying coastal areas with large populations. The cost of adaptation could amount to at least 5-10% of GDP. Mangroves and coral reefs are projected to be further degraded, with additional consequences for fisheries and tourism.
New
studies confirm that Africa is one of the most vulnerable continents to
climate variability and change because of multiple stresses and low adaptive
capacity. Some adaptation to current climate variability is taking place,
however, this may be insufficient for future changes in climate.
| Asia |
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Glacier melt in the Himalayas is projected to increase flooding, rock avalanches from destabilised slopes, and affect water resources within the next two to three decades. This will be followed by decreased river flows as the glaciers recede.
Freshwater availability in Central, South, East and Southeast Asia particularly in large river basins is projected to decrease due to climate change which, along with population growth and increasing demand arising from higher standards of living, could adversely affect more than a billion people by the 2050s.
Studies mainly in industrialised countries.
Coastal areas, especially heavily-populated mega-delta regions in South, East and Southeast Asia, will be at greatest risk due to increased flooding from the sea and in some mega-deltas flooding from the rivers.
Climate change is projected to impinge on sustainable development of most developing countries of Asia as it compounds the pressures on natural resources and the environment associated with rapid urbanisation, industrialisation, and economic development.
It is projected that crop yields could increase up to 20% in East and Southeast Asia while it could decrease up to 30% in Central and South Asia by the mid-21st century. Taken together and considering the influence of rapid population growth and urbanization, the risk of hunger is projected to remain very high in several developing countries.
Endemic
morbidity and mortality due to diarrhoeal disease primarily associated
with floods and droughts are expected to rise in East, South and Southeast
Asia due to projected changes in hydrological cycle associated with global
warming. Increases in coastal water temperature would exacerbate the abundance
and/or toxicity of cholera in South Asia.
| Australia and New Zealand |
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As a result of reduced precipitation and increased evaporation, water security problems are projected to intensify by 2030 in southern and eastern Australia and, in New Zealand, in Northland and some eastern regions.
Significant loss of biodiversity is projected to occur by 2020 in some ecologically-rich sites including the Great Barrier Reef and Queensland Wet Tropics. Other sites at risk include Kakadu wetlands, south-west Australia, sub-Antarctic islands and the alpine areas of both countries.
Ongoing coastal development and population growth in areas such as Cairns and Southeast Queensland (Australia) and Northland to Bay of Plenty (New Zealand), are projected to exacerbate risks from sea-level rise and increases in the severity and frequency of storms and coastal flooding by 2050.
Production from agriculture and forestry by 2030 is projected to decline over much of southern and eastern Australia, and over parts of eastern New Zealand, due to increased drought and fire. However, in New Zealand, initial benefits to agriculture and forestry are projected in western and southern areas and close to major rivers due to a longer growing season, less frost and increased rainfall.
The
region has substantial adaptive capacity due to well-developed economies
and scientific and technical capabilities, but there are considerable constraints
to implementation and major challenges from changes in extreme events.
Natural systems have limited adaptive capacity.
| Europe |
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For the first time, wide ranging impacts of changes in current climate have been documented: retreating glaciers, longer growing seasons, shift of species ranges, and health impacts due to a heat wave of unprecedented magnitude. The observed changes described above are consistent with those projected for future climate change.
Nearly all European regions are anticipated to be negatively affected by some future impacts of climate change and these will pose challenges to many economic sectors. Climate change is expected to magnify regional differences in Europe's natural resources and assets. Negative impacts will include increased risk of inland flash floods, and more frequent coastal flooding and increased erosion (due to storminess and sealevel rise). The great majority of organisms and ecosystems will have difficulties adapting to climate change. Mountainous areas will face glacier retreat, reduced snow cover and winter tourism, and extensive species losses (in some areas up to 60% under high emission scenarios by 2080).
In Southern Europe, climate change is projected to worsen conditions (high temperatures and drought) in a region already vulnerable to climate variability, and to reduce water availability, hydropower potential, summer tourism, and in general, crop productivity. It is also projected to increase health risks due to heat waves and the frequency of wildfires.
In Central and Eastern Europe, summer precipitation is projected to decrease, causing higher water stress. Health risks due to heat waves are projected to increase. Forest productivity is expected to decline and the frequency of peatland fires to increase.
In Northern Europe, climate change is initially projected to bring mixed effects, including some benefits such as reduced demand for heating, increased crop yields and increased forest growth. However, as climate change continues, its negative impacts (including more frequent winter floods, endangered ecosystems and increasing ground instability) are likely to outweigh its benefits.
Adaptation
to climate change is likely to benefit from experience gained in reaction
to extreme climate events, by specifically implementing proactive climate
change risk management adaptation plans.
| Latin America |
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By mid-century, increases in temperature and associated decreases in soil water are projected to lead to gradual replacement of tropical forest by savanna in eastern Amazonia. Semi-arid vegetation will tend to be replaced by arid-land vegetation. There is a risk of significant biodiversity loss through species extinction in many areas of tropical Latin America.
In drier areas, climate change is expected to lead to salinisation and desertification of agricultural land. Productivity of some important crops are projected to decrease and livestock productivity to decline, with adverse consequences for food security. In temperate zones soybean yields are projected to increase.
Sea-level rise is projected to cause increased risk of flooding in low-lying areas.
Increases in sea surface temperature due to climate change are projected to have adverse effects on Mesoamerican coral reefs, and cause shifts in the location of south-east Pacific fish stocks.
Changes in precipitation patterns and the disappearance of glaciers are projected to significantly affect water availability for human consumption, agriculture and energy generation.
Some
countries have made efforts to adapt, particularly through conservation
of key ecosystems, early warning systems, risk management in agriculture,
strategies for flood drought and coastal management, and disease surveillance
systems. However, the effectiveness of these efforts is outweighed by:
lack of basic information, observation and monitoring systems; lack of
capacity building and appropriate political, institutional and technological
frameworks; low income; and settlements in vulnerable areas, among others.
| North America |
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Moderate climate change in the early decades of the century is projected to increase aggregate yields of rainfed agriculture by 5-20%, but with important variability among regions. Major challenges are projected for crops that are near the warm end of their suitable range or depend on highly utilised water resources.
Warming in western mountains is projected to cause decreased snowpack, more winter flooding, and reduced summer flows, exacerbating competition for over-allocated water resources.
Disturbances from pests, diseases, and fire are projected to have increasing impacts on forests, with an extended period of high fire risk and large increases in area burned.
Cities that currently experience heat waves are expected to be further challenged by an increased number, intensity and duration of heat waves during the course of the century, with potential for adverse health impacts. The growing number of the elderly population is most at risk.
Coastal
communities and habitats will be increasingly stressed by climate change
impacts interacting with development and pollution. Population growth and
the rising value of infrastructure in coastal areas increase vulnerability
to climate variability and future climate change, with losses projected
to increase if the intensity of tropical storms increases. Current adaptation
is uneven and readiness for increased exposure is low.
| Polar Regions |
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In the Polar Regions, the main projected biophysical effects are reductions in thickness and extent of glaciers and ice sheets, and changes in natural ecosystems with detrimental effects on many organisms including migratory birds, mammals and higher predators. In the Arctic, additional impacts include reductions in the extent of sea ice and permafrost, increased coastal erosion, and an increase in the depth of permafrost seasonal thawing.
For Arctic human communities, impacts, particularly resulting from changing snow and ice conditions, are projected to be mixed. Detrimental impacts would include those on infrastructure and traditional indigenous ways of life.
Beneficial impacts would include reduced heating costs and more navigable northern sea routes.
In both polar regions, specific ecosystems and habitats are projected to be vulnerable, as climatic barriers to species' invasions are lowered.
Already
Arctic human communities are adapting to climate change, but both external
and internal stressors challenge their adaptive capacities. Despite the
resilience shown historically by Arctic indigenous communities, some traditional
ways of life are being threatened and substantial investments are needed
to adapt or re-locate physical structures and communities.
| Small Islands |
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Small islands, whether located in the Tropics or higher latitudes, have characteristics which make them especially vulnerable to the effects of climate change, sea level rise and extreme events.
Deterioration in coastal conditions, for example through erosion of beaches and coral bleaching, is expected to affect local resources, e.g., fisheries, and reduce the value of these destinations for tourism.
Sea-level rise is expected to exacerbate inundation, storm surge, erosion and other coastal hazards, thus threatening vital infrastructure, settlements and facilities that support the livelihood of island communities.
Climate change is projected by the mid-century to reduce water resources in many small islands, e.g., in the Caribbean and Pacific, to the point where they become insufficient to meet demand during low rainfall periods.
With higher temperatures, increased invasion by non-native species is expected to occur, particularly on middle and high-latitude islands.
Magnitudes of impact can now be estimated more systematically for a range of possible increases in global average temperature.Since the IPCC Third Assessment, many additional studies, particularly in regions that previously had been little researched, have enabled a more systematic understanding of how the timing and magnitude of impacts may be affected by changes in climate and sea level associated with differing amounts and rates of change in global average temperature.
Entries have been selected which are judged to be relevant for people and the environment and for which there is high confidence in the assessment. All entries of impact are drawn from chapters of the Assessment, where more detailed information is available.
Depending on circumstances, some of these impacts could be associated with "key vulnerabilities", based on a number of criteria in the literature (magnitude, timing, persistence/reversibility, the potential for adaptation, distributional aspects, likelihood and "importance" of the impacts). Assessment of potential key vulnerabilities is intended to provide information on rates and levels of climate change to help decisionmakers make appropriate responses to the risks of climate change.
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| Source: IPCC; UNEP and WMO, 6 April 2007 |
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