Stephen Polasky, Fesler-Lampert Professor of Ecological/Environmental Economics at University of Minnesota, opened the panel by reiterating that world is becoming increasingly urbanized, and that it is important to assess how exactly this movement toward urbanization affects resource sustainability. He highlighted the importance of research on urban systems as new and innovative ideas, technologies, and policies, are increasingly being driven and produced by cities.
John Crittenden, director of the Brook Byers Institute for Sustainable Systems at the Georgia Institute of Technology, provided an overview of commonly used and emerging urban sustainability indicators. From a global perspective, Dr. Crittenden said that human society has many challenges in its path forward in reaching sustainability. He provided an example to illustrate what he termed society’s global report card in regards to interfering with natural cycles. The expanding world economy and increasing population creates more waste than nitrogen, phosphorous, water, and carbon cycles can handle, and society may not use or recycle enough renewable resources and material to offset consequent damages. To date, renewable energy sources contribute 18 percent of global energy production, yet 28 percent of material use. Meanwhile, 8.6 gigatons of carbon is being released into the atmosphere and 4,000 billion cubic meters of freshwater is being utilized, which is about 43 percent of available freshwater globally.
Dr. Crittenden grouped sustainability indicators and metrics into three broad categories defined as ecological sustainability indicators, social sustainability indicators, and the environmental sustainability index. Ecological sustainability indicators such as ecological, carbon, and water footprint assessments evaluate the impacts on a certain natural system and/or cycle. Social sustainability indicators measure impacts across the social and economic spectrum. Examples include the genuine progress indicator that attempts to monetize all economic, social, and environmental factors; the happy planet index that measures the degree to which long and happy lives are achieved; and the human development index that combines life expectancy, educational development, and income. The environmental sustainability index uses indicators that measure two main components of environmental health and ecosystem vitality (Figure 3-1). Though many of these indicators may add value to sustainability decision making in urban areas, he noted that further development of these indicators was needed and thus developed a toolbox to help address gaps in knowledge (Figure 3-2). The toolbox’s improvement strategies are grouped into three layers: data and design, modeling, and decision support.
Within the data and design layer, Dr. Crittenden indicated that modelers, scientists, and analysts could benefit from monitoring systems from within the larger infrastructure in which they exist. The cyber-physical infrastructure
of the smart grid illustrates one example where the devices involved in the grid, such as electric vehicles, wind turbines, and battery storage, rely on the flows and stocks that occur between the controllers, smart meters, thermostats, and measurements of the larger local control layer—the dependence of these activities continues to scale up until one assesses the interactions between policies, business models, and economic functions of the market layer (Figure 3-3).
Bio-inspired design, or biomimicry, adapts systems by applying ideas or structures from the natural world, such as designing a building to mimic the passive heat and cooling system of a termite mound. Dr. Crittenden provided examples from systems-thinking design, bio-inspired design, and data-enabled design to intervene in these systems and achieve positive outcomes within larger infrastructure. Systems-thinking design may stray from the traditional approach of building urban infrastructure by considering the interdependencies and interactions between socioeconomic and physical factors. The increase in low-impact development represents such new systems-thinking design of urban areas which, for example, incorporate ecology into grey infrastructure and reconfigures a city to handle water as a sponge instead of a transmitter of water to large pipes, storm-water collection, or other large water reservoirs. This added green infrastructure may create new recreational and public spaces that can improve social well-being, physical health, and property values.
Finally, the progression in data analytics improved the ability of urban sustainability decision makers to design around thousands of data points and individual preferences. In one study conducted by the Atlanta Regional Commission, a framework for autonomous vehicles was designed based on comments from more than 1,500 individuals, which identified future challenges such as protecting autonomous vehicles from cybersecurity threats, understanding how these vehicles will influence traffic congestion, and the policy incentives the city will need to establish the vehicles.1
Nevertheless, the data and design layer of urban sustainability modeling may need further development, and Dr. Crittenden stressed that science would benefit from analysis of the root of urban systems and structures—the citizens—and identify society’s preferences and values in order to create agent-based models that reflect how society’s decisions affect movement and interactions in the larger urban system. Cities and researchers frequently apply crowdsourcing to determine what citizens value and evaluate if the services that are provided fulfill these wants. In one study that Dr. Crittenden termed a Mechanical Turk study, the decisions made by a cohort of Atlanta citizens were analyzed at the microlevel of where these individuals lived, consumed, and worked. The study found that the city’s development strategies of designing new buildings and highways did not align with the citizens’ desires for an improved overall quality of life. In response, an agent-based model was developed that considered optimal land-use plans for Atlanta that provided amenities favorable to the adoption of a more sustainable infrastructure and improved quality of life.2
Dr. Crittenden acknowledged that agent-based modeling could improve its ability to capture complex and emergent properties of urban systems. As an example of progression in agent-based modeling, he presented the SMARTRAQ project (Strategies for Metropolitan Atlanta’s Regional Transportation and Air Quality), an urban planning model of development pattern scenarios in Atlanta. Researchers are now able to assess information on more than 1.3 million parcels and project the city’s growth patterns and potential to adopt compact growth practices based on an average of 35 attributes for each parcel, such as road type or owner-occupied tax value. Dr. Crittenden projected that growth will continue to sprawl and favor low to medium residential development in a business-as-usual scenario. More compact development action and policy, however, can reduce urban sprawl, increase land devoted to forests and greenways, and further commercial and residential growth.
He additionally discussed how enhancement of sustainability indicators and metrics can provide valuable decision support in urban areas, particularly advancements in network analysis. He concluded his remarks by highlighting the issue of urban sprawl, and presented a comparative fractal dimension study of the Washington, D.C., road network versus the Atlanta road network. In the study, a high fractal dimension number indicated more connections to roads, easing single passenger transit and urban sprawl, which, in turn, results in a higher carbon footprint. He reinforced this assumption by finding a higher fractal dimension figure and a higher carbon footprint for Atlanta of 3.36 and 1.52 metric tons of carbon per capita per year, respectively. The fractal dimension figure and carbon footprint for Washington, D.C., was 2.80 and 1.07 metric tons of carbon per capita per year.
William Solecki, professor in the Department of Geography at Hunter College–City University of New York, discussed the connections between science and public policy in the context of cities. In terms of trends, most population growth over the next several decades will occur in urban areas, specifically in low-income countries and small- to medium-sized cities. In addition, recent international agreements, protocols, and understandings have seen an emergence of urban issues on the international policy agenda. For example, urban areas featured prominently during the 2015 United Nations World Conference on Disaster Risk Reduction,3 in Sustainable Development Goal 11, and in the upcoming Habitat III summit.4
1 Atlanta Regional Commission. 2015. The Region’s Plan: Phase II Survey Report. Online. Available at http://documents.atlantaregional.com/The-Atlanta-Region-s-Plan/ARC-Phase-2-Survey-Report-Final.pdf. Accessed March 24, 2016.
2 Atlanta Regional Commission. 2014. ARC’s Regional Plan Online – Phase 1: Data Analysis and Summary Report. Prepared by AECOM. Online. Available at http://documents.atlantaregional.com/The-Atlanta-Region-s-Plan/Regional-Plan-Public-Survey-Phase-I-data-analysisreport.pdf. Accessed March 24, 2016.
3 United Nations Office for Disaster Risk Reduction (UNISDR) Third UN World Conference On Disaster Risk Reduction, March 14–18, 2015, Sendai, Japan.
4 United Nations Conference on Housing and Sustainable Urban Development (Habitat III), “The New Urban Agenda,” October 17–20, 2016, Quito, Ecuador.
Dr. Solecki discussed the emergence of urbanization science and its conceptualization of urban areas, urban issues, and urbanization as a set of intersecting systems (Figure 3-4). Urbanization science research investigates interactions within this conceptualization and attempts to translate these data into information useful for policy and decision makers. Recent developments in translating urbanization science to policy include the robustness of data information about urban processes, uncertainty measures, likelihood measures, and climate work, which have highlighted the increased need for nuanced scientific information for decision making. Questions of current indicators and monitoring have also emerged, such as what indicators are still considered appropriate for cities
or how can existing monitoring systems be integrated and directed toward new policy agendas of sustainability, resilience, or climate change adaptation? The urban domain has witnessed a tremendous amount of growth in community organization, bottom-up approaches, boundary organizations, and demands for open and transparent processes in decision making, and coproduction of knowledge.
Dr. Solecki further addressed traditional computational modeling, the role it plays in urban decision-making processes, and advancement in physical engineering (e.g., the built environment) and ecological system modeling (e.g., how urban ecosystems respond to stresses, evolve, and adapt to change) over the last 15 years. Computational models, however, may still require improvement to support decision making for the social side of urban issues. Other challenges may include a lack of appropriate data, capacity to operationalize urban systems analysis, basic science and expertise to address questions of sustainability, financial resources, and trust in products. One of the most flood-prone cities in the world—Calcutta, India—faces a data availability challenge because of a lack of access to a fully developed flood extent map for city officials to use in flood management.
For the most part, urban practitioners and researchers have done little work in creating an integrated modeling approach for urban spatial planning, with the exception of some European Union countries and China. Dr. Solecki indicated that city leaders work at the right level of governance to spearhead sustainability action due to their local understanding of their community’s unique systems, risks, exposures, and vulnerabilities. In addition, these leaders retain links with local academic and research communities, direct contact with constituents, day-to-day management, and engagement with regional coordination efforts. Nevertheless, a number of challenges may remain for urban leaders, such as managing at a metropolitan scale, financing mitigation and adaptation measures, bridging differences between high- and lower-income cities, and maintaining momentum across municipal administrations and election cycles.
He also reiterated various types of science-policy linkages in an urban setting, such as the emergent concept of coproduction of knowledge where different groups come together in a collaborative process to define issues, solve problems, and produce and disseminate knowledge. One example of this concept of coproduction of knowledge is Future Earth, an international research platform bringing together scientists of all disciplines, society, and users of science to coordinate new and interdisciplinary approaches for global environmental change and sustainability. Another example includes the National Oceanic and Atmospheric Administration’s (NOAA) Regional Integrated Sciences and Assessments (RISA) Program (see Figure 3-5), which promotes collaboration in the scientific community and information development directly with stakeholders to understand weather and climate risk issues, manage knowledge networks, and advance science policies (Figure 3-5). Dr. Solecki concluded by emphasizing the significant development of policy-relevant research on urban systems. Cogeneration of knowledge is an innovative frontier; however, a number of limitations remain, including the predominance of power relations, legal constraints, time intensiveness, stakeholder fatigue, and the possibility of the scientific community losing its “outside-the-box, cutting edge” thinking.
Karen Seto, professor of geography and urbanization and associate dean of research at the Yale School of Forestry and Environmental Studies, addressed various advances in urban systems that could inform sustainability science. Dr. Seto said that for urban systems, it is projected that cities will build more buildings and roads between now and 2050 than currently exist around the world. Further, if the built environment in the developing world reaches similar levels to developed countries, global carbon dioxide emissions will not meet the 2015 international agreement from Paris of holding the increase in global average temperatures to below 2 degrees Celsius above preindustrial levels. The dominant conceptualization of cities considers urban environments within spatial boundaries of a city with a minimal focus on what happens outside a city. She indicated that bringing cities and the process of urbanization into the sustainability dialogue would benefit this urban conceptualization, provide new frameworks that look beyond urban impacts on resources or the environment, and incorporate the interactions between people and the environment that extend beyond the spatial boundaries of a city.
As an example of progress in urban domains that could further inform sustainability science, Dr. Seto pointed to the creation of new institutions and programs on urban science. The Centre for Advanced Spatial Analysis at the University College London is an example of an institution looking at spatial patterns and fractal analysis, while the Senseable City Lab at the Massachusetts Institute of Technology provides another example of an institution focusing on “sensing” cities in real time. Dr. Seto notes, however, that these institutions and programs have not produced many new insights that challenge current understanding of urban systems.
In light of the recent adoption of the Sustainable Development Goals, and Goal 11 on sustainable cities and communities, progress has been made in developing metrics and indicators for urban systems. The scientific community, however, has experienced a large degree of pushback in developing indicators and targets due to difficulty in data consistency and availability across countries. Other recent developments in urban science include a new interest by international organizations, development agencies, and foundations in developing new understandings and conceptualizations of cities.
Dr. Seto acknowledged that despite advancements in urban sustainability metrics and indicators, a large disconnect exists between the information produced by urban science and the information usable in management at the local scale. This disconnect is a challenge for efforts to fight climate change. There are also challenges to urban sustainability from resource demands and poverty, and the options to address these problems at the local level may be constrained by regional or national contexts.
Dr. Seto highlighted results from the International Panel on Climate Change (IPCC) that reflect on a need for new efforts and developments in science to better inform sustainability science in cities.5 If the top 50 carbon-emitting cities were aggregated into one country, that country would still be the third largest emitter behind China and the United States. Large variations within or between developed and developing country cities’ average per capita energy use suggest that developed country cities operate more efficiently than developing country cities (Figure 3-6). Scientist with different background would likely interpret these data differently. For example, a political scientist would interpret these graphs as illustrative of the varying institutions and governance across cities, an economist would point to the difference in economic structures, and urban planners would consider variations in transportation modes. Categorizing cities as either developed (Annex I) or developing (Annex II) does not provide the depth of needed information.
5 Seto K.C., et al. 2014. Human settlements, infrastructure, and spatial planning. In Climate Change 2014: Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, ed. O. Edenhofer et al. Cambridge, UK, and New York, NY, USA: Cambridge University Press.
Dr. Seto indicated that a large share of current research focuses on smart cities and sensing cities; however, further research should focus on different metrics and indicators of well-being rather than on ones targeting efficiency. In data gathering and analysis, the scientific community should look beyond measuring city growth. Observations and models of urban systems still lack sophistication compared with parallel observations and models of climate systems that have progressed not only spatially but also in complexity. An example of improving models of urban systems comes from researchers at the University of New Hampshire who utilized different types of satellite data to analyze the three-dimensional structure of cities.6 Additional research, she said, is needed to understand the interplay between the social and environmental dimensions of urbanization. Dr. Seto stressed the importance of progressing from models that only analyze interactions within a city to a global model that incorporates global hinterlands and feedbacks across multiple levels (see Figure 3-7). Dr. Seto concluded her remarks by identifying two important research needs urban science can contribute to sustainability science—updating frameworks and theoretical development and improving data and metrics that analyze linkages and flows over space and time. She also added that since a sustainable city has yet to be defined, progress toward sustainability in the urban domain will remain a challenge.
In the question-and-answer session, the panelists discussed shared socioeconomic pathways (SSPs)7 as a framework for considering development and progress toward sustainability. Dr. Solecki noted that the urban community is beginning to utilize such thought processes, but that the notion of the trajectory of cities remains crucial, and in many cases these trajectories are not necessarily within the realm of SSPs. Dr. Seto added that the urban community would benefit from alternative thinking about science for urbanization given the pace and magnitude of its development, noting that the urban community currently thinks in terms of optimization and best scenarios. The scientific community has yet to define the optimal solution for urban sustainability or what a sustainable city would look like.
6 Frolking, S., et al. 2013. A global fingerprint of macro-scale changes in urban structure from 1999 to 2009. Environmental Research Letters 8(2):024004.
7 The SSPs are part of a new framework that the climate change research community has adopted to facilitate the integrated analysis of future climate impacts, vulnerabilities, adaptation, and mitigation. The framework is built around a matrix that combines climate forcing on one axis (as represented by the Representative Forcing Pathways) and socio-economic conditions on the other. Together, these two axes describe situations in which mitigation, adaptation, and residual climate damage can be evaluated. Van Vuuren et al. 2012. A Proposal for a New Scenario Framework to Support Research and Assessment in Different Climate Research Communities. Global Environmental Change 222(1): 21-35.
The panelists also discussed efficiency indicators related to urban sustainability. Dr. Solecki said that for city managers, an efficiency indicator’s ability to compare options using dollars allows for an easy measurement, but such an indicator does not account for all inputs, such as wellness and happiness, that are needed to achieve a sustainable city. Dr. Crittenden argued that the management of complex and diverse entities within a city is a more important role than ensuring urban efficiency by adopting a more sustainable infrastructure. Dr. Seto agreed, questioning whether efficiency measures really give the urban community any indication of well-being.
A final question posed to the panelists concerned the justification of thinking about urban systems as closed systems rather than coupled-urban systems, given that rural-urban migration affects both urban communities and rural communities. Dr. Seto said that such a framing reflects issues of data limitations, and in part the current methods of data analysis, wherein she reiterated the importance of advancements in theoretical frameworks for urban systems. Dr. Crittenden offered an alternative response, stressing that at this stage, the focus on interactions within cities—the city as an ecosystem—is still important for sustainability given the objectives of optimizing resource use and efficiency.