Effects
Health
Extreme event— hurricanes, extreme heat and floods are easily contributed by higher temperature. An increase in the frequency of extreme events may result in more event-related deaths, injuries, infectious diseases, and stress-related disorders. Heart problems, asthma, the elderly, the very young and the homeless can be especially vulnerable to extreme heat.
Sensitive Diseases—Climate change may increase the risk of some infectious diseases, particularly those diseases that appear in warm areas and are spread by mosquitoes and other insects. These "vector-borne" diseases include malaria, dengue fever, yellow fever, and encephalitis. Warm temperatures can increase air and water pollution. With that, the global population at risk from vector-borne malaria will increase by between 220 million and 400 million in the next century.
Air Quality—Respiratory disorders may be exacerbated by warming-induced increases in the frequency of smog (ground-level ozone) events and particulate air pollution.
*climate change is expected to bring a few benefits to health, including fewer deaths due to exposure to cold. Nonetheless, the IPCC (Intergovernmental Panel on Climate Change) has concluded that, overall (globally), negative climate-related health impacts are expected to outweigh positive health impacts during this century.
Agriculture and Food Supply
While food production may benefit from a warmer climate, the increased potential for droughts, floods and heat waves will cause farmers a lot of problems. Additionally, the enduring changes in climate, water supply and soil moisture could make it less feasible to continue crop production in certain regions.
Climate Factors
- Average temperature increase
- Change in rainfall amount and patterns
- Rising atmospheric concentrations of CO2
- Pollution levels such as tropospheric ozone
Average temperature increase: An increase in average temperature can
1) lengthen the growing season in regions with a relatively cool spring and fall;
2) adversely affect crops in regions where summer heat already limits production; 3) increase soil evaporation rates, and
4) increase the chances of severe droughts.
Change in rainfall amount and patterns: Changes in rainfall can affect soil erosion rates and soil moisture, both of which are important for crop yields.
Increasing atmospheric CO2 levels: can act as a fertilizer and enhance the growth of some crops such as wheat, rice and soybeans. However, other aspects of climate change (e.g., temperature and precipitation changes) may temper any beneficial CO2 fertilization effect.
Higher levels of ground level ozone: limit the growth of crops.
Forests
Climate change effects on forests are likely to include changes in forest health and productivity and changes in the geographic range of certain tree species. These effects can in turn alter timber production, outdoor recreational activities, water quality, wildlife and rates of carbon storage.
- Air temperature
- Atmospheric CO2 concentrations
- Fire and Disease
Air temperature: Changes in temperature and precipitation are expected to change forest location, composition, and productivity.
CO2 level: growth rates may increase with increasing levels of atmospheric CO2, but these effects are expected to saturate over time as tree communities adjust to increased CO2 levels. Increased carbon sequestration would remove more CO2 from the atmosphere, whereas carbon losses through forest disturbances would result in more CO2 entering the atmosphere. Net carbon uptake by terrestrial ecosystems is likely to peak before mid-century and then weaken or even reverse, thus making climate change more severe.
Fire and Disease: Increased temperatures could increase fire risk in areas that become drier due to climate change. Climate change could also promote the rapid increase of diseases and pests that attack tree species.
Ecosystems and Biodiversity
During the course of this century the resilience of many ecosystems (their ability to adapt naturally) is likely to be exceeded by an unprecedented combination of change in climate and in other global change drivers (especially land use change and overexploitation).
Coastal Zones and Sea Level Rises
In the last century, sea level rose 5 to 6 inches. Higher temperatures are expected to further raise sea level by expanding ocean water, melting mountain glaciers and small ice caps, and causing portions of Greenland and the Antarctic ice sheets to melt. IPCC estimates that the global average sea level will rise between 0.18 to 0.59 meters (0.6 and 2 feet) in the next century.
Rising sea levels flood wetlands and other low-lying lands, erode beaches, intensify flooding, and increase the salinity of rivers, bays, and groundwater tables.
Storms and Flooding: Shore erosion also increases vulnerability to storms, by removing the beaches and dunes that would otherwise protect coastal property from storm waves. Sea level rise also increases coastal flooding from rainstorms, because low areas drain more slowly as sea level rises. Higher temperatures lead to increasing rainfall intensity during severe storms. An increase in the intensity of tropical storms would increase flood and wind damages.
Coastal Water Supply: Rising sea level increases the salinity of both surface water and ground water through salt water intrusion. Salinity increases in estuaries also can harm aquatic plants and animals that do not tolerate high salinity. When the water is saline, people won’t be able to use the water.
Water Resources
Temperature is predicted to rise in most areas, but is generally expected to increase more in inland areas and at higher latitudes. Higher temperatures will increase loss of water through evaporation. In areas where precipitation increases sufficiently, net water supplies may not be affected or they may even increase. In other areas where precipitation remains the same or decreases, net water supplies would decrease.
Water Quality: Higher temperatures reduce dissolved oxygen levels, which can have an effect on aquatic life. Where streamflow and lake levels fall, there will be less dilution of pollutants; however, increased frequency and intensity of rainfall will produce more pollution and sedimentation. Flooding can affect water quality, as large volumes of water can transport contaminants into water bodies and also overload storm and wastewater systems.
Heavier precipitation will very likely increase waterborne diseases and affect water quality, and higher variability of precipitation will make water management more difficult.
Energy Production and Use
Energy use: Changes in temperature due to climate change could affect our demand for energy. There may also be changes in energy consumed for other climate-sensitive processes, such as pumping water for irrigation in agriculture. Rising temperatures and associated increases in evaporation may increase energy needs for irrigation.
Public Lands, Recreational Opportunities, and Natural Resources
National Parks and other Protected Areas: National parks and other protected areas are currently susceptible to events influenced by climatic variability, such as drought, wild fires, impaired air quality, and severe storms. These beautiful places are continually being ruined.
Outdoor recreation and tourism: Shifts in temperature and precipitation patterns could lead to shifts in a variety of outdoor tourism and recreation opportunities, such as skiing, fishing and hunting. Ex winter recreation, such as skiing, snowmobiling, and ice fishing, are likely to be affected by climate change, as might the businesses associated with them. As permafrost in far northern locations like Alaska begins melting, it may no longer support roads, buildings and other structures that had been built on it, affecting everyday lives of residents, as well as travel and commerce.
Polar Regions
Arctic Climate system:
- Average temperatures in the Arctic have risen at almost twice the rate as temperatures in the rest of the world over the past few decades.
- Widespread melting of glaciers and sea ice.
- Melting of Arctic glaciers is a contributing factor to sea-level rise around the world.
- Warming is very likely to alter the release and uptake of greenhouse gases from soils, vegetation, and coastal oceans.
- Reduction in sea ice is very likely to have devastating consequences for polar bears, ice-dependent seals, and local people for whom these animals are a primary food source.
- It is very likely that average ice thickness in the Arctic has decreased by up to 1 meter.
- Arctic impacts will have implications for biodiversity around the world because migratory species depend on breeding and feeding grounds in the Arctic.
- As frozen ground thaws, many existing buildings, roads, pipelines, airports, and industrial facilities are likely to be destabilized.
- Agricultural production, including access to food, in many African countries and regions is projected to be severely affected by climate variability and change causing starvation.
- Toward the end of the 21st century, projected sea-level rise will affect low-lying coastal areas with large populations.
- Glacier melt in the Himalayas is projected to increase flooding, increase rock avalanches from destabilized slopes, and affect water resources within the next two to three decades.
- 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 from higher standards of living, could adversely affect more than a billion people by the 2050s.
- Coastal areas, especially heavily populated megadelta regions in South, East and Southeast Asia, will be at greatest risk due to increased flooding from the sea and, in some megadeltas, flooding from rivers.
- Crop yields could increase up to 20 percent in East and Southeast Asia, while they could decrease up to 30 percent in Central and South Asia by the mid-21st century.
- Sickness and death due to diarrheal disease, primarily associated with floods and droughts, are expected to rise in East, South and Southeast Asia due to projected changes in the hydrological cycle associated with global warming.
- Significant loss of biodiversity is projected to occur by 2020 in some ecologically rich sites, including the Great Barrier Reef and Queensland Wet Tropics.
- 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 are projected in western and southern areas and close to major rivers due to a longer growing season, less frost and increased rainfall.
- 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.
- 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.
- In Central and Eastern Europe, summer precipitation is projected to decrease, causing higher water stress. Health risks due to heatwaves 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.
- 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.
- In drier areas, climate change is expected to lead to salinization and desertification of agricultural land. Productivity of some important crops is 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.
- Changes in precipitation patterns and the disappearance of glaciers are projected to significantly affect water availability for human consumption, agriculture, and energy generation.
- Warming in western mountains is projected to cause decreased snowpack, more winter flooding, and reduced summer flows, exacerbating competition for over-allocated water resources.
- Moderate climate change in the early decades of the century is projected to increase aggregate yields of rain-fed agriculture by 5- 20 percent, but with important variability among regions. Major challenges are projected for crops that are near the warm end of their suitable range or which depend on highly utilized water resources.
- Cities that currently experience heatwaves are expected to be further challenged by an increased number, intensity and duration of heatwaves during the course of the century, with potential for adverse health impacts. Elderly populations are most at risk.
- Pasterze, Austria's longest glacier, was about 2 kilometers longer in the 19th C. but is now completely out of sight from this overlook on the Grossglockner High Road.
- Coastal communities and habitats will be increasingly stressed by climate change impacts interacting with development and pollution.
- Hurricanes are likely to be stronger on a warmer earth. A recent study showed how an increase in the power of Atlantic hurricanes over the past 20 years is correlated with warmer ocean water in the Atlantic.
- 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 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 mid- and high-latitude islands.
Biological and human system:
Antarctica: Satellite observations show no significant change in Antarctic sea-ice extent over the 1973-2005 period.
Summary
Averaged surface air temperature is projected by models to warm 1.1-6.4°C (2 to 11.5°F) by 2100 relative to 1990, and globally averaged sea level is projected by models to rise 18-59 cm (7.2 to 23.6 inches or 0.18- 0.59m) by 2100.
The warming would vary by region, and would be accompanied by changes in precipitation, changes in the variability of climate, and changes in the frequency and intensity of some extreme climate phenomena.
International Impacts
Africa:
Asia:
Australia and New Zealand:
Europe:
Latin America:
North America:
Grinnell glacier, Glacier National Park, USA, which has receded almost out of sight
Small Islands:
Effects: Information from U.S. Environmental Protection Agency
(http://www.epa.gov/climatechange/index.html)
