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Human settlements are affected by climate change in one of three major ways:
1. The economic sectors that support the settlement are affected. For example, resource availability could be affected. The demand for the goods and services produced in a particular city could change.
2. Some aspects of physical infrastructure, buildings, urban services, and specific industries may be directly affected. For example, buildings and infrastructure in delta cities may be affected by coastal and river flooding; urban energy demand may increase or decrease because of changed space heating and space cooling needs; and coastal and mountain tourism may be affected by temperature and rainfall changes, and sea-level rise.
3. Populations may be directly affected. For example, extreme weather episodes may lead to changes in deaths, injuries, or illness. People’s health may improve because there is less cold stress or it may deteriorate as a result of increased heat stress and disease. People may be displaced because of sea level rise.
According to the IPCC’s second assessment report (SAR), the most vulnerable communities include:
1. Poor coastal and agrarian communities in arid areas
2. Settlements built on hazardous sites (such as wetlands or steep hillsides) in or around urban areas in developing countries.
Flooding and landslides:
The most widespread direct risk to human settlements from climate change is flooding and landslides. Projected increases in rainfall intensity and, in coastal areas, sea-level rise will be the culprits. Cities on rivers and coasts are particularly at risk. Figure 1 shows the projected impact on low-lying areas. Scientists project a 20.7% loss of land with 14.8 million people affected in Bangladesh.
Figure 1. Projected loss of land in Bangladesh
Source: IPCC 2001. Climate Change 2001: Impacts, Adaptations and Vulnerability. Contribution of Working Group II to the Third Assessment Report of the Intergovernmental Panel on Climate Change [McCarthy, J.J. et al. (eds.)]. Cambridge University Press, Cambridge, UK. p569
Scientists estimate that several times the average annual number of people will be flooded by coastal storm surges. That is an increase of 75 to 200 million people for a 40-cm sea-level rise by the 2080s compared 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.
If the sea level rises by 0.5 m (projected by about the year 2100), 32% of Egypt will be flooded with a loss of $35 billion US dollars (IPCC Climate Change 2001 WG II section 184.108.40.206). Property loss in the US will run between $20 to $150 billion. It will cost countries many billions to protect their coasts from sea level rise. Settlements in water-deficient regions of the world would face even higher demands for water if the climate became warmer.
Tropical cyclones would become more destructive in a warmer climate as a result of warmer oceans. Infrastructure in permafrost regions is vulnerable to warming.
Permafrost melting could lead to increased landslides, loss of foundation stability and increased damage from freeze-thaw cycles.
Heat waves would have a more severe effect on human health and productivity, and would have the greatest influence on the weakest part of the population (including the old, chronically ill and very young).
Rapid urbanization in low-lying coastal areas of both the developing and developed world is greatly increasing population densities. This increases the value of human-made structures exposed to coastal climatic extremes such as tropical hurricanes (also called cyclones or typhoons) and therefore the cost of potential losses.
Many cities in the world have huge squatter settlements and crowded neighbourhoods with poor shelter. These people have little or no access to safe water and public health services. These areas are highly vulnerable to these disastrous events.
Cities and towns that are very dependent mainly on agriculture, forestry, or fisheries (directly affected by climate) are particularly vulnerable. 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.
Industry and Energy:
Energy demand is expected to increase for space cooling and decrease for space heating as the climate warms. The net affect will vary from region to region.
Some energy production and distribution systems may suffer a reduction in supply. Consumers may find their energy supply less reliable. Other areas may have the opposite effect and benefit from climate change.
Industry sectors that are sensitive to climate include:
- Transportation operations and infrastructure
- Energy transportation and transmission
- Offshore oil and gas
- Thermal power generation
- Water availability for industry
- Pollution control
- Coastal-sited industry
- Tourism and recreation.
Urbanization (proportion of population living in urban areas) is expected to continue. The likely trend toward a more urban world means that the impacts of climate change on human settlements will increasingly affect urban populations, not rural or traditional settlements.
A poleward intensification of agricultural, forestry and mining activities is occurring, resulting in increased settlement in Canada’s northern regions and even in arctic areas. Climate changes could significantly affect settlements these regions. For example, some arctic activities rely on snow roads, which would have to be replaced with other forms of transport as a result of climate changes.
Concentrations of populations and industry with buildings. rooftops and roads, produce an urban environment that develops what is known as an ‘urban heat island effect’.
More energy from the sun is absorbed and released by these urban surfaces which increases the average overall or ambient temperature for the urban area. This ‘urban heat island effect’ can raise the air temperature in a city by 1- 4 C degrees.
Refer to a world map and choose one continent with coastal populations.
1. Determine the elevation above sea level of at least 3 key cities along one portion of the coast of the continent you have chosen.
2. Draw a line to show where the 0.5m increase in the expected sea or water level will be for the new sea level for these 3 cities.
3. Check the current populations of these 3 cities and calculate the total of persons to be relocated. Refer to 7.2.2 section to see what parts of Ontario might be affected by this contour line.
ACTIVITY 2 Research:
A. The Chinese project daming part of the Yangzte River to be completed in 2006.
1. How many people were moved in order to flood one major stretch of the river?
2. What were the choices given to the people ordered to resettle?
3. What support did the government give these residents other than compensation eg inventorying precious artifacts, building museums.
B. Eastern Asia
1. After the tsunami damaging parts of India, Sira Lanka, Thailand, Indonesia were damaged? At what elevation where these areas?
C. North America
Hurricanes need warm water to feed them moisture and pick up speed. They do this as the air currents move westward across the Atlantic north of the equator to reach the Caribbean and arrive at Florida
1. Research the areas of the state that were damaged in 2004 and the total cost of the damage done in the hurricane season.
2. Compare the last 5 years with previous records for total damage and total number of hurricane events of at least a force of 3 and document trends seen.
3. What human settlement factors cause an increase in damage?