NCA Regional Input Reports

Urban Systems, Sectors, and Prospects for Action

William D. Solecki, Cynthia Rosenzweig

• Publisher: NCA Regional Input Reports
• Year: 2022
• ISBN:
  9781610919791
• Topic: Architecture
• Subtopic: Architecture General

Approximately 80% of the U.S. population now lives in urban metropolitan areas, and this number is expected to grow significantly in the coming years. At the same time, the built infrastructure sustaining these populations has become increasingly vulnerable to climate change. Stresses to existing systems, such as buildings, energy, transportation, water, and sanitation are growing. If the status quo continues, these systems will be unable to support a high quality of life for urban residents over the next decades, a vulnerability exacerbated by climate change impacts. Understanding this dilemma and identifying a path forward is particularly important as cities are becoming leading agents of climate action.Prepared as a follow-up to the Fourth National Climate Assessment (NCA), Climate Change and U.S. Cities documents the current understanding of existing and future climate risk for U.S. cities, urban systems, and the residents that depend on them. Beginning with an examination of the existing science since 2012, chapters develop connections between existing and emerging climate risk, adaptation planning, and the role of networks and organizations in facilitating climate action in cities. From studies revealing disaster vulnerability among low-income populations to the development of key indicators for tracking climate change, this is an essential, foundational analysis. Importantly, the assessment puts a critical emphasis on the cross-cutting factors of economics, equity, and governance.Urban stakeholders and decision makers will come away with a full picture of existing climate risks and a set of conclusions and recommendations for action. Many cities in the United States still have not yet planned for climate change and the costs of inaction are great. With bold analysis, Climate Change and U.S. Cities reveals the need for action and the tools that cities must harness to effect decisive, meaningful change.
 

Chapter 1

Introduction: Cities and Climate Change Connections

CONVENING LEAD AUTHORS:
William Solecki (City University of New York),
Cynthia Rosenzweig (NASA GISS)

LEAD AUTHORS:
Radley Horton (Columbia University),
Alex de Sherbinin (Columbia University – CIESIN)

THE GOAL OF THIS BOOK IS TO ASSESS the new knowledge and information about climate change and U.S. cities.¹ It is now known that climate change is already being experienced by U.S. cities through gradual shifts in climate variables and through extreme events (Melillo et al. 2014). This book attempts to document the state-of-the-art understanding of current and future climate risk for U.S. cities, urban systems and the residents that depend on them. Contemporary climate change represents an era of increasing climate variability that is driving urban managers and residents to be more flexible and adaptive in response to these dynamic risks. Urban systems such as water, energy, and transportation infrastructure are designed and managed to operate within an expected range of environmental conditions. Climate change is associated with gradual and punctuated shifts in the environmental baseline of cities and in turn is placing increased stress on city life.

This book is an expansion and extension of the urban focused assessment research presented in the 2014 U.S. National Climate Assessment and a follow-up to the work being done as part of the Fourth National Climate Assessment due to be released at the end of 2018. Urban issues have played an important role in large scale climate assessment activities since the late 1990s. For example, as part of the initial National Climate Assessment in 2000, Rosenzweig and Solecki (2001) led the development of the first major assessment of how a large city and its surrounding metropolitan region could be impacted by climate variability and change. The work focued on the New York Metropolitan Region. For the 2009 Assessment, climate change and cities issues were presented within several sections of the report. The results of 2009 assessment provided some updates of the findings from the 2000 asssesment effort with a focus on new climate models and associated impacts and vulnerabilities. The 2014 National Climate Assessment for this first time includes a chapter with urban in its title (i.e., Chapter 11 – Vulnerability, Urban, and Infrastructure). The NCA4 also will include an urban related chapter.

The research team assembled for this book focused on an assessment of the scholarly literature of climate change and U.S. cities, with an emphasis on research findings generated in the past five years (since early 2012). The scope of the book is to create a foundational document on climate change and U.S. cities that assesses state-of-the-art knowledge and information across a broad set of topics. The assessment is designed to be policy relevant that is particularly important as cities have become agents of climate action moving forward after the COP21 meeting in December of 2015 and the resulting Paris Agreement. The audience for this current assessment book includes a wide variety of interested parties, including policymakers, academics, and science and technical experts, as well as the general public.

1.1 Urban Issues - Results from previous U.S. National Climate Assessments

As part of the 2000 U.S. National Climate Assessment the Climate Change and a Global City Report was published (Rosenzweig and Solecki 2001). The most significant conclusions from that assessment illustrated the key potential impacts, vulnerabilities, opportunities and challenges across a set of set of urban sectors including water, energy, transportation, public health, and decision-making. The assessment documented that climate change already was having an impact on the region and that significant populations and assets were at risk. Because of the tightly coupled character of urban systems, integrative or cascading impacts from extreme climate events could occur in urban areas.

For the 2009 national climate assessment, further advancement was made with respect to understanding climate change in cities. Urban issues were embedded in several sections of the report including in the chapter entitled Society, small sections within two regional chapters (Northeast and Southwest), and occasional references to cities and high-density settlements in other chapters. Differential vulnerability of populations and infrastructure was highlighted in the report. It was stated that urban areas have unique vulnerabilities to climate change, as these areas are already stressed systems, have large at-risk populations and intense concentrations of critical infrastructure, and existing climate risks such as heat islands, and inland and coastal flooding. The 2009 report also provided additional insights into the actions that cities had begun to take to adapt to climate change, particularly with respect to protection of vulnerable infrastructure and populations during extreme climate events such as heat waves and storm surge events. Specific activities noted include heat early warning systems and the procurement of heat resistant materials, and initial discussions regarding the increasing vulnerability of near-shore locations.

For the 2014 National Climate Assessment, several key findings were derived including that U.S. cities are already experiencing the effects of climate change and greater impacts are expected with the onset of an increasingly dynamic climate. This was deemed to be especially important since approximately 245 million residents, or 80% of the U.S. population, now live in urban metropolitan areas, the definition of which includes core cities and extended suburban and exurban areas. This number is expected to grow to 364 million by 2050 (U.S. Census Bureau 2012). The built infrastructure within cities and connected to cities which sustains these populations has become increasingly fragile and deficient and increasingly vulnerable to climate change (Solecki et al. 2013; Wilbanks et al. 2012). Existing built infrastructure systems (such as buildings, energy, transportation, water, and sanitation systems) are expected to become increasingly stressed and, if the status quo continues, unable to support a high quality of life for urban residents over the next decades – especially when the impacts of climate change are added to the equation (McCrea et al. 2011).

The U.S. National Climate Assessment currently incorporates a sustained assessment process in which climate modeling, adaptation and resiliency program evaluation, and implementation of monitoring climate change indicators and metrics have been developed and are in various stages of implementation. These ongoing activities have provided the foundation for the ongoing 4^th National Climate Assessment (NCA4).

1.2 Cities and Climate Change – Their Emerging Future Together

As presented by global climate modeling scenarios, future climate change in cities will manifest as directional shifts in average annual climate-related conditions such as higher average annual temperature, more rapid sea level rise as well as an increased frequency and intensity of extreme weather events including extended heat waves and more intense storms. Observed climate data from the early 20th century to the present illustrate a shift in the frequency and magnitude of extreme events, particularly with respect to an increased rate of heavy precipitation events and the occurrence of heat waves. Worst-case scenarios for future climate change include instances where multiple extreme events occur at the same time – for example, a large coastal storm with tidal surge and flooding coincident with an extreme heat event.

Climate change will increase the exposure and vulnerability of cities and their residents to these hazards. Climate-related shifts represent significant challenges as well as potential opportunities for these systems and their managers. Increased climate variability and directional change poses a series of interrelated challenges to the country’s cities. The impact of climate will be compounded by the fact that the U.S. is highly urbanized, with about 80% of its population living in cities and metropolitan areas. The potential impact of climate change is compounded by the fact that many cities depend on critical infrastructure, like water and sewage systems, roads, bridges, and power plants, that are aging and in need of repair or replacement. Rising sea levels, storm surges, heat waves, and extreme weather events will compound these issues, stressing or even overwhelming these essential services.

Cities have become early responders to climate change challenges and opportunities due to two simple facts (Rosenzweig et al. 2010). Urban areas have large and growing populations that are vulnerable for many reasons to climate variability and change. Cities also depend on extensive infrastructure systems and the resources that support them. These systems often extend to, or derive from, rural locations at great distances from urban centers. Urban residents are particularly vulnerable to disruptions in essential infrastructure services, in part because many of these infrastructure systems are reliant and interdependent on each other. For example, electricity is essential to multiple systems, and a failure in the electrical grid can affect water treatment, transportation services, telecommunications, and public health. As climate change impacts increase, climate-related events also will have large consequences for significant numbers of people living in cities or the extended suburbs of metropolitan regions. These changing conditions also create opportunities and challenges for urban climate adaptation, and many cities have begun adopting plans to address these changes.

Events like Hurricane Katrina and Sandy and the more recent Hurricanes Harvey, Irma, and Maria and the fires and flooding in California have alerted the nation’s urban residents to the emergence of a new climate normal that is a result of climate change. In this new normal, unprecedented extreme events can occur and the prospects of gradual environmental shifts, like sea level rise, will exacerbate future environmental stress on urban systems and the daily life of urban residents. A rich literature of specific case studies on these topics have emerged (e.g. Berardy and Chester 2017; Cheng et al. 2017; Hauer 2017) as well as systematic appraisals and frameworks regarding how to manage these risks (e.g., Depietri and McPhearson; Reckien 2017; Solecki et al. 2017; Wallace 2017). Another growing issue, also incorporated into this book, is the recognition that climate change is not isolated from existing risks, challenges, and opportunities present within the structure and functioning of cities. These elements are directly linked and in this context, climate change will potentially make existing urban climate risks worse and result in impediments to economic development (see as example Dinan 2017; Gornitz et al. 2017; and Petkova 2017). This book attempts to capture the key findings and new information that emerges from this collective yet diverse literature and in turn provide a benchmark of new knowledge.

1.3 Scientific Background

This book takes an explicitly systems-level perspective to detail and understand the connections between climate change and cities. The book focuses on how the climate shifts influence changes in urban systems such as water and energy supply, transportation and public health, and what societal context conditions like economics, governance, legal regimes and insurance mediate and influence these connections.

To understand and illustrate the connections between climate change and cities at the sector and service level, the study focuses on how climate change will shift the function, structure, or organization of specific sectors or services and thereby reveal system-level challenges for adaptation strategies, vulnerabilities and opportunities. How these impacts, vulnerabilities, and adaptation strategies are mediated by a set of cross-cutting factors such as economics, equity, and governance is another critical component of the assessment process.

1.4 Guiding Framework

The assessment utilizes several conceptual outlines to structure its analytical discussion of climate change and cities. The assessment utilizes an urban climate risk conceptual framework for examining climate risk, climate scenarios, and the urbanization process. The urban climate risk framework utilized here incorporates several basic elements including existing and emerging climate risk, interactions with urban sectors and services which help illustrate a set of vulnerabilities, impacts, and adaptation strategies which in turn are mediated by a set of cross-cutting issues and urbanization context. The diagram below illustrates of some these basic relationships.

Figure 1-1 shows a simple conceptual framework that illustrates how current and emerging climate risks are translated through urban sectors and services thereby fostering the development of a variety of vulnerabilities, impacts, and adaptation challenges and opportunities. This process is deeply connected to and influenced by ongoing urbanization processes in individual cities and extended metropolitan regions. The urbanization processes connect the climate risk, urban systems and vulnerabilities, impacts, and adaptation through a set of cross-cutting issues such as governance capacity and resources including the level of local expertise and budget structure.

This assessment recognizes that there are several existing climate hazards present in U.S. cities. Key hazards include sea level rise and coastal storm surge, heat waves, intense precipitation and riverine and street level flooding, drought, extreme wind events, urban heat islands, secondary air pollutants, and cold air events including frozen precipitation. Current key climate risks, which include conditions of likelihood and consequence faced by U.S. cities, include the following:

Figure 1-1. Urbanization Risk Assessment Framework. Source: authors.

• Populations vulnerable to river and coastal flooding;

• Major population centers on the nation’s coasts have assets and populations exposed to flooding and associated equity issues;

• Economic loss potential much greater than insured loss; significant non-market value losses also a risk; and,

• Major coastal storm events (e.g., hurricane) could result in ~ hundreds of billions of dollars of economic losses.

• Public health crises and economic losses resulting from a large scale extreme heat event.

Climate change in most cases will exacerbate these risks, with exception of the frequency of extreme cold events which will likely decrease over time. The nation will experience more days of extreme heat events particularly in the southern half of the U.S., as well as more days of extreme precipitation particularly in the Northeast and Midwest. As highlighted in Chapter 2, many areas of the country also have experienced significant relative and absolute population growth in th...

Table of contents

• Cover Page
• Title Page
• Copyright Page
• Contents
• Acknowledgments
• Chapter 1: Introduction: Cities and Climate Change Connections
• Chapter 2: Urban Systems and Climate Change in Context
• Chapter 3: Urban Systems and Services: Vulnerabilities and Impact
• Chapter 4: Urban Climate Adaptation Planning, Governance, and Economics
• Chapter 5: Sustained Urban Climate Assessment
• Chapter 6: Conclusions and Recommendations: Prospects for Action
• About the Editors