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4.5. Human Settlements, Energy, and Industry
Human settlements are integrators of many of the climate impacts initially
felt in other sectors and differ from each other in geographic location, size,
economic circumstances, and political and institutional capacity. As a consequence,
it is difficult to make blanket statements concerning the importance of climate
or climate change that will not have numerous exceptions. However, classifying
human settlements by considering pathways by which climate may affect them,
size or other obvious physical considerations, and adaptive capacities (wealth,
education of the populace, technological and institutional capacity) helps to
explain some of the differences in expected impacts. [7.2]
Human settlements are affected by climate in one of three major ways:
- Economic sectors that support the settlement are affected because of changes
in productive capacity (e.g., in agriculture or fisheries) or changes in market
demand for goods and services produced there (including demand from people
living nearby and from tourism). The importance of this impact depends in
part on whether the settlement is rural -- which generally means that it
is dependent on one or two resource-based industries -- or urban, in which
case there usually (but not always) is a broader array of alternative resources.
It also depends on the adaptive capacity of the settlement. [7.1]
- 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. For example, buildings and infrastructure in deltaic
areas may be affected by coastal and river flooding; urban energy demand may
increase or decrease as a result of changed balances in space heating and
space cooling; and coastal and mountain tourism may be affected by changed
seasonal temperature and precipitation patterns and sea-level rise. Concentration
of population and infrastructure in urban areas can mean higher numbers of
persons and higher value of physical capital at risk, although there also
are many economies of scale and proximity in ensuring well-managed infrastructure
and service provision. When these factors are combined with other prevention
measures, risks can be reduced considerably. However, some larger urban centers
in Africa, Asia, Latin America, and the Caribbean, as well as smaller settlements
(including villages and small urban centers), often have less wealth, political
power, and institutional capacity to reduce risks in this way. [7.1]
- Population may be directly affected through extreme weather, changes in
health status, or migration. Extreme weather episodes may lead to changes
in deaths, injuries, or illness. For example, health status may improve as
a result of reduced cold stress or deteriorate as a result of increased heat
stress and disease. Population movements caused by climate changes may affect
the size and characteristics of settlement populations, which in turn changes
the demand for urban services. The problems are somewhat different in the
largest population centers (e.g., those of more than 1 million population)
and mid-sized to small-sized regional centers. The former are more likely
to be destinations for migrants from rural areas and smaller settlements and
cross-border areas, but larger settlements generally have much greater command
over national resource. Thus, smaller settlements actually may be more vulnerable.
Informal settlements surrounding large and medium-size cities in the developing
world remain a cause for concern because they exhibit several current health
and environmental hazards that could be exacerbated by global warming and
have limited command over resources. [7.1]
Table TS-3 classifies several types of climate-caused
environmental changes discussed in the climate and human settlement literatures.
The table features three general types of settlements, each based on the one
of the three major mechanisms by which climate affects settlements. The impacts
correspond to the mechanism of the effect. Thus, a given settlement may be affected
positively by effects of climate change on its resource base (e.g., more agricultural
production) and negatively by effects on its infrastructure (e.g., more frequent
flooding of its water works and overload of its electrical system). Different
types of settlements may experience these effects in different relative intensities
(e.g., noncoastal settlements do not directly experience impacts through sea-level
rise); the impacts are ranked from overall highest to lowest importance. Most
settlement effects literature is based on 2xCO2 scenarios or studies
describing the impact of current weather events (analogs) but has been placed
in context of the IPCC transient scenarios. [7.1]
| Table TS-3: Impacts of climate change on human
settlements, by impact type and settlement type (impact mechanism).a,b |
 |
| |
Type of Settlement, Importance Rating, and Reference
|
|
| |
Resource-Dependent
(Effects on Resources)
|
Coastal-Riverine-Steeplands
(Effects on Buildings and Infrastructure)
|
Urban 1+ M
(Effects on Populations)
|
Urban <1 M
(Effects on Populations)
|
|
| Impact Type |
Urban, High Capacity
|
Urban, Low Capacity
|
Rural, High Capacity
|
Rural, Low Capacity
|
Urban, High Capacity
|
Urban, Low Capacity
|
Rural, High Capacity
|
Rural, Low Capacity
|
High Capacity
|
Low Capacity
|
High Capacity
|
Low Capacity
|
Confidencec
|
|
| Flooding, landslides |
L-M
|
M-H
|
L-M
|
M-H
|
L-M
|
M-H
|
M-H
|
M-H
|
M
|
M-H
|
M
|
M-H
|
****
|
|
| Tropical cyclone |
L-M
|
M-H
|
L-M
|
M-H
|
L-M
|
M-H
|
M
|
M-H
|
L-M
|
M
|
L
|
L-M
|
***
|
|
| Water quality |
L-M
|
M
|
L-M
|
M-H
|
L-M
|
M-H
|
L-M
|
M-H
|
L-M
|
M-H
|
L-M
|
M-H
|
***
|
|
| Sea-level rise |
L-M
|
M-H
|
L-M
|
M-H
|
M
|
M-H
|
M
|
M-H
|
L
|
L-M
|
L
|
L-M
|
**** (** for resource-dependent)
|
|
Heat/cold waves
|
L-M
|
M-H
|
L-M
|
M-H
|
L-M
|
L-M
|
L-M
|
L
|
L-M
|
M-H
|
L-M
|
M-H
|
*** (**** for urban)
|
|
| Water shortage |
L
|
L-M
|
M
|
M-H
|
L
|
L-M
|
L-M
|
M-H
|
L
|
M
|
L-M
|
M
|
*** (** for urban)
|
|
| Fires |
L-M
|
L-M
|
L-M
|
M-H
|
L-M
|
L-M
|
L-M
|
L-M
|
L-M
|
L-M
|
L-M
|
M
|
* (*** for urban)
|
|
| Hail, windstorm |
L-M
|
L-M
|
L-M
|
M-H
|
L-M
|
L-M
|
L-M
|
M
|
L-M
|
L-M
|
L-M
|
L-M
|
**
|
|
Agriculture/ forestry/fisheries productivity
|
L-M
|
L-M
|
L-M
|
M-H
|
L
|
L
|
L
|
L
|
L
|
L-M
|
L-M
|
M
|
***
|
|
| Air pollution |
L-M
|
L-M
|
L
|
L
|
--
|
--
|
--
|
--
|
L-M
|
M-H
|
L-M
|
M-H
|
***
|
|
Permafrost
melting
|
L
|
L
|
L-M
|
L-M
|
L
|
L
|
L
|
L
|
--
|
--
|
L-M
|
L-M
|
****
|
|
| Heat islands |
L
|
L
|
--
|
--
|
L
|
L
|
--
|
--
|
M
|
L-M
|
L-M
|
L-M
|
***
|
|
Climate change has the potential to create local and regional conditions that
involve water deficits and surpluses, sometimes seasonally in the same geographic
locations. The most widespread serious potential impacts are flooding, landslides,
mudslides, and avalanches driven by projected increases in rainfall intensity
and sea-level rise. A growing literature suggests that a very wide variety
of settlements in nearly every climate zone may be affected (established but
incomplete). Riverine and coastal settlements are believed to be particularly
at risk, but urban flooding could be a problem anywhere storm drains, water
supply, and waste management systems are not designed with enough capacity or
sophistication (including conventional hardening and more advanced system design)
to avoid being overwhelmed. The next most serious threats are tropical cyclones
(hurricanes or typhoons), which may increase in peak intensity in a warmer world.
Tropical cyclones combine the effects of heavy rainfall, high winds, and storm
surge in coastal areas and can be disruptive far inland, but they are not as
universal in location as floods and landslides. Tens of millions of people live
in the settlements potentially flooded. For example, estimates of the mean annual
number of people who would be flooded by coastal storm surges increase several-fold
(by 75 million 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 estimated to be tens of billions of dollars for individual
countries such as Egypt, Poland, and Vietnam. In the middle of Table
TS-3 are effects such as heat or cold waves, which can be disruptive to
the resource base (e.g., agriculture), human health, and demand for heating
and cooling energy. Environmental impacts such as reduced air and water quality
also are included. Windstorms, water shortages, and fire also are expected to
be moderately important in many regions. At the lower end are effects such as
permafrost melting and heat island effects -- which, although important locally,
may not apply to as wide a variety of settlements or hold less importance once
adaptation is taken into account. [7.2,
7.3]
Global warming is expected to result in increases in energy demand for spacing
cooling and in decreased energy use for space heating. Increases in heat waves
add to cooling energy demand, and decreases in cold waves reduce heating energy
demand. The projected net effect on annual energy consumption is scenario- and
location-specific. Adapting human settlements, energy systems, and industry
to climate change provides challenges for the design and operation of settlements
(in some cases) during more severe weather and opportunities to take advantage
(in other cases) of more benign weather. For instance, transmission systems
of electric systems are known to be adversely affected by extreme events such
as tropical cyclones, tornadoes, and ice storms. The existence of local capacity
to limit environmental hazards or their health consequences in any settlement
generally implies local capacity to adapt to climate change, unless adaptation
implies particularly expensive infrastructure investment. Adaptation to warmer
climate will require local tuning of settlements to a changing environment,
not just warmer temperatures. Urban experts are unanimous that successful environmental
adaptation cannot occur without locally based, technically and institutionally
competent, and politically supported leadership that have good access to national-level
resources. [7.2,
7.3, 7.4,
7.5]
Possible adaptation options involve planning of settlements and their infrastructure,
placement of industrial facilities, and making similar long-lived decisions
to reduce the adverse effects of events that are of low (but increasing) probability
and high (and perhaps rising) consequences. Many specific conventional and advanced
techniques can contribute to better environmental planning and management, including
market-based tools for pollution control, demand management and waste reduction,
mixed-use zoning and transport planning (with appropriate provision for pedestrians
and cyclists), environmental impact assessments, capacity studies, strategic
environmental plans, environmental audit procedures, and state-of-the-environment
reports. Many cities have used a combination of these strategies in developing
"Local Agenda 21s." Many Local Agenda 21s deal with a list of urban problems
that could closely interact with climate change in the future. [7.2,
7.5]
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