finding 11.3 : key-message-11-3

Interdependent networks of infrastructure, ecosystems, and social systems provide essential urban goods and services (very high confidence). Damage to such networks from current weather extremes and future climate will adversely affect urban life (medium confidence). Coordinated local, state, and federal efforts can address these interconnected vulnerabilities (medium confidence).

This finding is from chapter 11 of Impacts, Risks, and Adaptation in the United States: The Fourth National Climate Assessment, Volume II.

Process for developing key messages:

Report authors developed this chapter through technical discussions of relevant evidence and expert deliberation and through regular teleconferences, meetings, and email exchanges. For additional information on the overall report process, see App. 1: Process. The author team evaluated scientific evidence from peer-reviewed literature, technical reports, and consultations with professional experts and the public via webinar and teleconferences. The scope of this chapter is urban climate change impacts, vulnerability, and response. It covers the built environment and infrastructure systems in the socioeconomic context of urban areas. This chapter updates findings from the Third National Climate Assessment and advances the understanding of previously identified urban impacts by including emerging literature on urban adaptation and emphasizing how urban social and ecological systems are related to the built environment and infrastructure. The five case-study cities were selected because they represent a geographic diversity of urban impacts from wildfire, sea level rise, heat, and inland flooding. The author team was selected based on their experiences and expertise in the urban sector. They bring a diversity of disciplinary perspectives and have a strong knowledge base for analyzing the complex ways that climate change affects the built environment, infrastructure, and urban systems.

Description of evidence base:

Research focusing on urban areas shows that climate change has or is anticipated to have a net negative effect on transportation,d2f3853a-5f20-4132-92c8-57da1b4d95fc,23e451ae-5f97-48cd-9b2d-73045ee9e38c,00e98394-26f1-45da-a5a3-e79b2b1a356f,38ce969d-14fa-4874-8b5e-0ee37f4ac79c food,9f559c9b-c78e-4593-bcbe-f07661d29e16,74b22e64-6fce-418b-9f5a-aac88b4c1ba8,3b4ad15d-6c3f-4421-8ea6-405a0568e262 housing,db26897b-7a6e-4c0a-81b6-e59aaa784de3 the economy,9f559c9b-c78e-4593-bcbe-f07661d29e16,db26897b-7a6e-4c0a-81b6-e59aaa784de3,a52c7e70-0bfb-48da-bf90-cd93805e2d04,514afdba-5220-424b-8b11-559478de7775,4506c479-732e-4cc9-ae58-b3ab323f5f45 ecology,ce2db20d-ff1b-407c-873e-fde134a7929c,ff1fea07-c899-4e5f-aff2-76510d06c57b public health,b75bf8c7-f76f-4fd9-98d4-fd8fa08341f2,ce2db20d-ff1b-407c-873e-fde134a7929c,f1e633d5-070a-4a7d-935b-a2281a0c9cb6,9f559c9b-c78e-4593-bcbe-f07661d29e16,4506c479-732e-4cc9-ae58-b3ab323f5f45,626796fa-3b99-431e-bbfb-6eae974e96ae energy,d2f3853a-5f20-4132-92c8-57da1b4d95fc,9f559c9b-c78e-4593-bcbe-f07661d29e16,0ab7f834-85a7-4e1f-8628-8c8dc765ae5b,6f0557d7-ccaf-4a6a-8dac-25e859410881 water,d2f3853a-5f20-4132-92c8-57da1b4d95fc,dc51f598-91c5-4e1c-851d-7498ec8f8e1c,db26897b-7a6e-4c0a-81b6-e59aaa784de3,fbfe4df4-0209-4593-9fe6-dd45f1a1abb1 and sports and recreation.b75bf8c7-f76f-4fd9-98d4-fd8fa08341f2,fbfe4df4-0209-4593-9fe6-dd45f1a1abb1,a4d671c3-8df4-4bc3-9c1e-ac340b9b2da5

Researchers have modeled and documented how negative effects on one system that provides urban goods and services cascade into others that rely on it.ce2db20d-ff1b-407c-873e-fde134a7929c,d2f3853a-5f20-4132-92c8-57da1b4d95fc,9f559c9b-c78e-4593-bcbe-f07661d29e16,73fa64e2-d10c-4e58-a237-6637fbcee870,dc51f598-91c5-4e1c-851d-7498ec8f8e1c,a52c7e70-0bfb-48da-bf90-cd93805e2d04,4506c479-732e-4cc9-ae58-b3ab323f5f45,0ab7f834-85a7-4e1f-8628-8c8dc765ae5b,6f0557d7-ccaf-4a6a-8dac-25e859410881 Several draw on the example of Superstorm Sandy. These effects scale up to the national economy and across to other sectors, creating longer-term hazards and vulnerabilities.9f559c9b-c78e-4593-bcbe-f07661d29e16,35e35ccf-1a66-4c2f-b852-7b1fe3bf3266,73fa64e2-d10c-4e58-a237-6637fbcee870,38ce969d-14fa-4874-8b5e-0ee37f4ac79c The energy–water nexus, defined as the reliance of energy and water systems on each other for functionality, is a good example of documented system interdependency.d2f3853a-5f20-4132-92c8-57da1b4d95fc,6f0557d7-ccaf-4a6a-8dac-25e859410881 Research indicates that direct or high-level climate impacts on a variety of urban sectors (such as transportation, energy, drinking water, storm water) have cascading economic, socioeconomic, and public health consequences.ce2db20d-ff1b-407c-873e-fde134a7929c,f1e633d5-070a-4a7d-935b-a2281a0c9cb6,9f559c9b-c78e-4593-bcbe-f07661d29e16,a52c7e70-0bfb-48da-bf90-cd93805e2d04,4506c479-732e-4cc9-ae58-b3ab323f5f45

The literature shows that coordinated resilience planning across sectors and jurisdictions to address interdependencies involves using models and plans,ce2db20d-ff1b-407c-873e-fde134a7929c,d2f3853a-5f20-4132-92c8-57da1b4d95fc,3b4ad15d-6c3f-4421-8ea6-405a0568e262,a801f371-29e2-4b63-9d99-0361f73453a1,38ce969d-14fa-4874-8b5e-0ee37f4ac79c,9715fdad-2824-404b-b7bc-57077f1ad28d,747e6b30-6afc-4520-af4b-660389e167ba finding effective intervention points,73fa64e2-d10c-4e58-a237-6637fbcee870 creating system redundancy,d2f3853a-5f20-4132-92c8-57da1b4d95fc,9715fdad-2824-404b-b7bc-57077f1ad28d and motivating behavioral change. Recent reports discuss how interdependencies among energy, water, transportation, and communications services inform adaptation strategies that span sectors.d2f3853a-5f20-4132-92c8-57da1b4d95fc,38ce969d-14fa-4874-8b5e-0ee37f4ac79c

New information and remaining uncertainties:

Interconnections among urban systems have been studied less extensively than climate change effects on individual urban sectors, and there are still gaps to be filled.b093b04e-26ca-4957-9fad-165e46d763bb,d8c54f0d-2378-4523-b144-e2bcc7cc0d7b,253c37ce-07d5-4ee0-8d5e-ce57f8f85b4a The complexity of urban systems leads to uncertainty and modeling challenges. System models need to account for interconnections, feedback loops, and cascading effects from rural areas, among urban sectors, and within a sector. Creating a comprehensive framework to understand these connections is difficult.b093b04e-26ca-4957-9fad-165e46d763bb,38a397d4-812d-4af6-98fb-8f74dd8632ac There is a lack of forward-looking models of how projected climate changes will impact interdependent urban systems. Cities do not usually have the range of data needed to fully analyze system connections.92d52175-98b2-40ab-9ca7-4196f3c5e8e0,a801f371-29e2-4b63-9d99-0361f73453a1 Mixed methods analysis, where professional experience and qualitative data supplement available datasets, may partially compensate for this problem.253c37ce-07d5-4ee0-8d5e-ce57f8f85b4a Despite information gaps, urban stakeholders are beginning to address system interconnections in adaptation efforts.3c3cc09b-c2d7-4c52-bf8f-c064efa78e93

While it has been demonstrated that climate change affects urban systems, the extent to which climate change will affect a given urban system is difficult to predict. It depends on the unique strengths and vulnerabilities of that system as well as the regional and local climate conditions to which the system is exposed.15c8ad4d-f96a-4bfb-8944-63d220e42f3b,00e98394-26f1-45da-a5a3-e79b2b1a356f,600365e7-3302-4ede-afa1-f5c4e9e468a1 Modifying factors include spatial layout, age of infrastructure, available resources, and ongoing resilience efforts.d2f3853a-5f20-4132-92c8-57da1b4d95fc,faddfbf9-dbd6-45d5-a3f8-1ee63ccaa29d Similarly, critical points of intervention are unique to each urban area. Local-scale analysis of vulnerability and resilience has not been done for most U.S. cities.92d52175-98b2-40ab-9ca7-4196f3c5e8e0,253c37ce-07d5-4ee0-8d5e-ce57f8f85b4a

The severity of future climate impacts and cascading consequences for urban networks depends on the magnitude of global climate change.00e98394-26f1-45da-a5a3-e79b2b1a356f Urban systems may be able to tolerate some levels of stress with only minor disruptions. Stresses of greater frequency, longer duration, or greater intensity may compromise a system’s ability to function.aba07260-60ad-44df-9810-29f23f46facd,d2f3853a-5f20-4132-92c8-57da1b4d95fc,73fa64e2-d10c-4e58-a237-6637fbcee870,dc51f598-91c5-4e1c-851d-7498ec8f8e1c,38ce969d-14fa-4874-8b5e-0ee37f4ac79c Models can reveal changes in the likelihood or frequency of occurrence for a particular type of extreme event (such as a 100-year flood), but they cannot predict when these events will occur or whether they will hit a particular city or town.afbe359c-8f8d-4bff-a7ad-a8964262de37

Assessment of confidence based on evidence:

There is very high confidence that urban areas rely on essential goods and services that are vulnerable to climate change because they are part of interdependent networks of infrastructure, ecosystems, and social systems. There is high confidence that extreme weather events have resulted in adverse cascading effects across urban sectors and systems, as there is documentation of a significant number of case studies of urban areas demonstrating these effects. It is projected with medium confidence that network damages from future climate change will disrupt many aspects of urban life, given that the complexity of urban life and the many factors affecting urban resilience to climate change make future disruptions difficult to predict. Similarly, there is medium confidence that addressing interconnected vulnerabilities via coordinated efforts can build urban resilience to climate change.

References :

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