Climate change and disasters affect critical socio-economic sectors in settlements (both formal and informal), water and energy supply and demand, and public health. Climate change impacts on these key sectors and the implications for disaster risk reduction effectiveness are presented in the following section. The impacts include (i) increased system variability and potential instability, (ii) increased potential for declines in systems productivity, (iii) challenges to current system efficiency, and (iv) exacerbation of existing inequities.
In urban areas, inequities will become more apparent as populations will be differentially able to relocate away from highly vulnerable locations, leading to changes in the spatial distribution and density of both formal and informal settlements. Degradation of building materials is also projected to occur. As warmer temperatures extend into higher latitudes, diseases never before seen might appear, or diseases that had long been considered eradicated may re-emerge. The health ramifications in some areas could be disastrous, especially in densely populated informal settlements. Water supply and demand will be affected as areas under drought will expand. While precipitation is expected to increase in some areas, water availability is projected to eventually decrease in many regions, including those where water is supplied by meltwater from mountains. For energy supply and demand, climate change will put increased pressure on energy infrastructure via rising cooling demand, as well as greater likelihood of supply disruption from extreme event impacts.
Increased variability and instability of sector operation could in some cases lead to beneficial conditions. For example, future climate change could result in more favorable winter conditions in many northern-latitude cities. In most situations, however, the impacts will be more likely to be detrimental to sector operation, especially in poor countries that will be affected the most by climate change, and result in declines in system efficiency and production, e.g., decline in local agricultural productivity, more frequent drinking water shortages in cities, and loss of housing to flooding and storm surge. Even if these impacts are not evident in the short or medium term, enhanced climate change increases the potential for these types of losses, and potential secondary impacts such as increased rural-to-urban migration if rural agricultural systems become less viable. Local and national management regimes need to be ready to respond to these new possibilities. For example, the drought of record or similar baseline can no longer be seen as the most extreme and as the benchmark for disaster and hazard planning.
Sectoral impacts from climate change will reflect the underlying social and environmental conditions within cities. People and places that are most vulnerable and least resilient will be those most affected by climate change. Urban residents of already drought-prone and water-limited areas of cities will be more likely exposed to increased climate variability. Other urban poor already living in higher-risk sites in cities, such as flood-plains or hill slopes, will be affected by more frequent and more severe floods or more massive landslides and mass wasting of hillsides.
In summary, climate change-related, sectoral impacts present a variety of challenges and opportunities for disaster risk reduction strategies. The challenges include a need for continuing reevaluation of existing plans and efforts to determine if they are to be responsive to the increased dynamism and changing baseline of the local environment; to the presence of increased numbers of more intensively marginalized and less-resilient populations and places; and to increased competition for limited funding and resources for climate change-related impacts (i.e., government funding and attention could be drawn away from disaster planning if the focus turns to address increasingly difficult economic and social stresses present in many cities).
The question of how to develop effective climate change adaptation strategies within the context of disaster risk reduction management approaches and a multitude of other demanding city-scale public policy pressures is discussed in the next section.