Revised to Reflect the Discussions at the U.S. Climate Forum

What Is the scope of the sector? What issues should be included? This assessment is concerned with possible vulnerabilities to impacts of climate change and climate variability in U.S. cities and communities: the places where most people live. Rather than being focused on elements of the natural environment, it deals with artificial built environments that are complex combinations of physical and social constructs. It considers how climate change and variability affect the structures and systems that humans design and build to alter their local physical environments in order to improve their quality of life and assure its sustainability. It also considers possible vulnerabilities to impacts on ends as well as means: the quality of life and the services that people expect from their cities and communities, such as education, health care, sanitation, and security. In short, the assessment may address vulnerabilities of the built infrastructure, the institutional infrastructure, the social infrastructure, human services (comfort, convenience, and mobility; land, housing, energy, water; sanitation and waste disposal; education; health; security; recreation), and linkage infrastructures: transportation and communication.

What Are Overlaps and Synergies with Other Sectors? Cities and communities are all about linkages. Urban and community settings are by their very nature tightly linked with regions beyond their borders due to the necessity to import food, water, and materials and to export solid and liquid wastes, products, and information. These linkages create powerful overlaps with food availability, water availability, ecosystems services, human health, and energy; and linkages with forestry services are one aspect of flows related to materials. The connecting fabric, of course, takes the form of transportation and communication systems. A different kind of overlap is with commerce, industry, and trade, which are among the major reasons why cities and communities develop and among the major determinants of their growth or decline. Here, too, cities and communities are affected by what happens in other regions as complements and competitors.

What Baseline Information Is Needed? The starting point for understanding vulnerabilities to impacts from climate variability and climate change is to understand urban places, processes, and stresses in the absence of climate change. Information needed for such an assessment includes the current state and projected evolution of things such as demographic change (population migration and distribution, wealth distribution, and commuting patterns), land use, infrastructure status, and a variety of mass fluxes (e.g., water, food, materials, waste). For this, a great deal of information is readily available from such sources as the U.S. Census, state agencies, and local governments, along with an extensive research literature on urban processes and human services. Information is often available on environmental connections such as local climate, environmental quality, and resource consumption as well as demography and economic activities.

The main limitation is not that information is scarce but that the different kinds of information are too seldom integrated, which makes it difficult to understand linkages between human systems and natural systems, such as climate. Establishing a firm baseline for anticipating and monitoring climate change impacts in urban areas is likely to call for progress in integrating data about urban processes across the boundaries of sectors and academic disciplines. In addition, because climate change issues have arisen so recently, some types of information needed to project vulnerabilities and impacts are missing, in some cases combined with a lack of enthusiasm for adding more items to an already-crowded agenda.

What Assessments Already Exist of Climate Change Impacts on Cities and Communities? Work to date is hardly comprehensive, but the IPCC Second Assessment Report in 1995 (Working Group II) included a chapter on human settlements as well as other chapters on related topics. More recently, a section on Human Settlements and Industry was prepared for the North America chapter of the IPCC Special Report on Regional Impacts. Other assessments are now emerging from the grassroots in the United States, through such efforts as the urban carbon dioxide reduction and cities for climate protection programs of the International Council on Local Environmental Initiatives (ICLEI) and the NASA-supported Global Change in Local Places research project.

In some parts of the country, such as the Metropolitan East Coast, independent groups have begun to develop assessments of climate impacts on cities and communities, driven by such climate-related concerns as El Niño and coastal hurricanes; and the richness of this diverse work -- from New York City to Los Angeles -- should not be underestimated, although few individuals (if any) have a full grasp of everything that might be useful to the national assessment.

What Key Groups Should Be Involved in this Assessment? The starting point is people in local cities and communities and the institutions that serve and represent them: local governmental agencies, local business groups, and local non-governmental, nonprofit organizations, such as civic groups, voluntary organization organized around issues, and local schools and colleges. In many cases, local leaders are represented by national associations, such as of cities, mayors, city managers, and counties.

At the national level, many U.S. federal agencies are deeply concerned with urban areas and urban services: Housing and Urban Development, Health and Human Services, Transportation, Energy, Environmental Protection, Emergency Management, and even Treasury. Most states have counterpart agencies as well and are involved in such critical functions as revenue collection and allocation, especially as federal budgets shrink. Similarly, in a one-person, one-vote democracy, the legislative branches of government are dominated by individuals who represent urbanized areas; and the judicial system deals with such issues as security and equity in urban areas and other settlements. In addition, at the national and regional levels business, labor, and voluntary organizations are active in addressing urban issues, including efforts to represent the poor and powerless.

What Are the Major Stresses on Cities and Communities and Their Quality of Life? Many cities and communities are currently delivering a satisfactory quality of life to a majority of their citizens. At the same time, however, most are faced with significant stresses related to two overarching factors: (1) continuing population and economic growth, combined with large-scale changes in urban form (e.g., abandonment of the urban core, suburbanization, and changes in the economic base); and (2) devolution of the federal government role in maintaining the quality of life in city and community settings.

Stresses that are currently important vary considerably from area to area, and their severity often depends on the effectiveness of local government and participative problem-solving. In most cases, however, the stresses include some of the following: (1) problems of growth: real estate development, congestion, growing service requirements; (2) social stresses: diversity/equity, security, a deteriorating "social net"; (3) economic stresses: economic restructuring, poverty; (4) an aging physical infrastructure, especially in older settlements; and (5) deteriorating environmental quality, along with increasing threats to human health.

Of these various stresses, a breakout group at the U.S. Climate Forum identified five as particularly serious: the uneven spatial pattern of population and economic growth, equity and diversity issues, institutional/jurisdictional fragmentation, federal devolution/declining revenue base, and fixed/aging infrastructure (see the Forum group summary).

How Might Climate Variability and Change Interact with These Stresses? Urban areas and other settlements are distinctive, compared with "natural" biomes, in the importance of second and third-order impacts of climate variability and change. These kinds of vulnerabilities and impacts are the most difficult to analyze, which suggests that urban impact assessment is especially affected by limitations of the impact assessment state of the art.

First-order implications include changes in temperature and precipitation, mainly noticeable in extreme events such as heat waves, blizzards, droughts, floods, or fire, or in changes in the cost of interior climate control or urban infrastructures; changes in storm frequencies and intensities; and sea level rise combined with storm surges, which could have a substantial impact on coastal areas. Coastal areas may be particularly vulnerable if sea level rise occurs.

Second-order implications include changes in the cost and quality of domestic water supplies, changes in disease vectors and other health impacts (including heat stress), changes in air quality (e.g., as warming increases concentrations of air pollutants), and the possibility that certain segments of the population may be especially impacted: those in risk-prone areas and situations, the poor, elderly, and very young.

Third-order implications include impacts of shifts in regional comparative advantage, which could affect jobs and incomes; impacts on consumers and local businesses of climate change abatement policies; and political and social tensions if and as impacts appear.

The main concern, of course, is with vulnerabilities to negative impacts, but it should be recognized that impacts of climate variability and change are likely to produce winners as well as losers. Some areas, and some people, will welcome warming. Some will welcome drying. Some will benefit from the misfortunes of others. Some will find business opportunities in global and national responses to climate change concerns. It is important to seek a balanced view of the implications of climate variability and change, which will vary greatly from place to place.

The U.S. Climate Forum group indicated that the greatest concerns at this time are extreme weather events, sea level rise/storm surges, 2d and 3d order impacts, especially impacted segments of the population, and increased uncertainty and opportunity costs.

What Coping Strategies Are Possible to Reduce Vulnerabilities? Strategies to cope with vulnerabilities to impacts of climate variability and change start with strong, effective, and well-informed local institutions. Beyond this general conclusion, coping strategies may include information and education strategies, strategies to make local institutions more adaptive, engineering/physical infrastructure investments (e.g., to increase resiliency with respect to sea level rise and storm surges in coastal areas and to reduce heat island impacts in urban areas), and regulatory initiatives: e.g., land-use controls, building standards, and water conservation programs. It appears that coastal areas need special attention, especially on the more gently sloping east coast of the U.S.

According to the U.S. Climate Forum group, important directions for coping include effective governance and institutions, community participation in assessments and response strategies, strategies to increase resiliency, and recognizing that coping well will produce opportunities.

What Are the Highest Priority Information Needs? In a situation where a great deal of data has been generated from the top down in the United States, the highest priority is to engage local stakeholders in a dialogue to match the available information base with local information needs and to explore the potentials of state of the art information technologies, such as Geographic Information Systems, for communicating relevant information to local parties. Most likely, this dialogue will identify information needs that would not be fully appreciated from a central point of view.

In addition to better data, an improved understanding of the interconnections within and between urban settings and the regions beyond is of utmost importance. Since cities and communities are fundamentally dependent on linkages, their greatest vulnerabilities probably lie in impacts of climate change and vulnerability on those linkages, which are not well enough understood. More generally, interconnections between natural and artificial environments and the processes that shape them are poorly understood as an integrated system, which undermines any effort to predict the effects of a change in one upon the other.

The U.S. Climate Forum group emphasized needs to improve understandings of relationships between settlement patterns and emissions, impacts, and responses; to provide better climatic and weather predictions; to better understand urban inflows/outflows, and to improve the understanding of 2d and 3d order impacts.