Altered frequencies and intensities of extreme weather, together with sea level rise, are expected to have mostly adverse effects on natural and human systems.
Table SPM.3. Examples of possible impacts of climate change due to changes in extreme weather and climate events, based on projections to the mid-to late 21st century. These do not take into account any changes or developments in adaptive capacity.
Phenomenon and direction of trend | Agriculture, forestry and ecosystems | Examples of major projected impacts by sector | |||
| Agriculture, forestryand ecosystems | Water resources | Human health | Industry, settlement and society | ||
| Over most land areas, warmer and fewer cold days and nights, warmer and more frequent hot days and nights | Virtually certain | Increased yields in colder environments; decreased yields in warmer environments; increased insect outbreaks | Effects on water resources relying on snowmelt; effects on some water supplies | Reduced human mortality from decreased cold exposure | Reduced energy demand for heating; increased demand for cooling; declining air quality in cities; reduced disruption to transport due to snow, ice; effects on winter tourism |
| Warmspells/heat waves.requency increasedovermost land areas | Very likely | Reduced yields in warmer regions due to heat stress; increased danger of wildfire | Increased water demand; water quality problems, e.g. algal blooms | Increased risk of heat-related mortality, especially for the elderly, chronically sick,very young and socially isolated | Reduction in quality of life for people in warm areas without appropriate housing; impacts on the elderly, very young and poor |
| Heavy precipitationevents. Frequency increases overmost areas | Very likely | Damage to crops; soil erosion, inability to cultivate land due to waterlogging of soils | Adverse effects on quality of surface and groundwater; contamination of water supply; water scarcity may be relieved | Increased risk of deaths, injuries and infectious, respiratory and skin diseases | Disruption of settlements, commerce, transport and societies due to flooding: pressures on urban and rural infrastructures; loss of property |
| Area affected by drought increases | likely | Land degradation; lower yields/crop damage and failure; increased livestock deaths;increased risk of wildfire | More widespread water stress | Increased risk of food and water shortage; increased risk of malnutrition; increased risk of water -and food- borne diseases | Water shortage for settlements, industry and societies; reduced hydropower generation potentials; potential for population migration |
| Intense tropical cyclone activity increases | likely | Damage to crops; windthrow (uprooting) of trees; damage to coral reefs | Power outages causing disruption of public water supply | Increased risk of deaths, injuries, water- and food-borne diseases; post- traumatic stress disorders | Disruption by flood and high winds; withdrawal of risk coverage in vulnerable areas by private insurers, potential for population migrations, loss of property |
| Increasedincidence of extreme high sea level (excludes tsunamis) | likely | Salinisation of irrigation water, estuaries and freshwater systems | Decreased freshwater availability due to saltwater intrusion | Increased risk of deaths and injuriesby drowning in floods; migration-related health effects | Costs of coastal protection versus costs of land-use relocation; potential for movement of populations and infrastructure; also see tropical cyclones above ; |
* SRES - Special Report on Emissions Scenarios
IPCC's technical paper on climate change and water cites the main water-related projected impacts for Asia as follows:
The per capita availability of freshwater in India is expected to drop from around 1,820 m3 currently to below 1,000 m3 by 2025 in response to the combined effects of population growth and climate change. [WGII 10.4.2.3]
More intense rain and more frequent flash floods during the monsoon would result in a higher proportion of runoff and a reduction in the proportion reaching the groundwater. [WGII 10.4.2]
Agricultural irrigation demand in arid and semi-arid regions of east Asia is expected to increase by 10% for an increase in temperature of 1oC. [WGII 10.4.1]
Coastal areas, especially heavily populated Asian megadelta regions, will be at greatest risk due to increased flooding from the sea and, in some megadeltas, flooding from rivers. [WGII 6.4, 10.4.3]
Changes in snow and glacier melt, as well as rising snowlines in the Himalayas, will affect seasonal variation in runoff, causing water shortages during dry summer months. One-quarter of China's population and hundreds of millions in India will be affected (Stern, 2007). [WGII 3.4.1,
(taken from Bates, B.C., Z.W. Kundzewicz, S. Wu and J.P. Palutikof, Eds., 2008: Climate Change and Water. Technical Paper of the Intergovernmental Panel on Climate Change, IPCC Secretariat, Geneva, 210 pp. Click here)