Cities are central to the climate change challenge, and their position is ever more important as the world’s population is becoming increasingly urban. City governments can play an active role in attempting to mitigate climate change, as well as in sheltering their residents from the negative consequences of climate change. In this topic, we examine the connections between cities and the management of these negative consequences of climate change.
Climate change affects hazard, vulnerability, and risk exposure in cities through a variety of direct and indirect relationships. Cities in many ways were first created as a means to more efficiently protect populations from hazards, whether they be physical (e.g., storms, droughts) or social (e.g., war, civil unrest) in origin. The very fact that cities are population centers illustrates the tension that city managers face with respect to hazards. They can be expected to help protect the populations that live within their cities’ borders; while, at the same time, the concentration of population in cities means that when disaster strikes a large number of people could be adversely impacted.
City governments are beginning to put a greater focus on adapting their cities to the inevitable effects of climate change. In its 2007 Fourth Assessment Report (AR4), the Intergovernmental Panel on Climate Change (IPCC, 2007a) concluded that there is a greater than 90 percent chance that the average global temperature increase over the last century was primarily caused by human activity. However, in the context of cities, several climate-induced challenges, such as increased flooding potential and its impacts on water supply, are still largely understudied.
Climate change and increased climate variability will alter the environmental baselines of urban locales. Shifts in climate and increased frequency of extreme events have direct impacts on water availability and quality, flooding and drought periodicity, and water demand. These dynamic changes will affect system processes within multiple sectors in cities interactively, increasing the uncertainty under which urban managers and decision-makers must operate.
In turn, a central objective of this topic is to review how this new information and uncertainty about climate risk is being integrated into effective and efficient adaptation planning at the city level. To address this issue, the topic first focuses broadly on the connection between climate change adaptation and more established disaster risk reduction strategies. Derived from these connections, we then present a climate risk assessment-based analysis of adaptive capacity in a diverse set of four city-focused case studies.