{"id":2255,"date":"2013-01-22T23:01:02","date_gmt":"2013-01-23T04:01:02","guid":{"rendered":"http:\/\/www.thenatureofcities.com\/?p=2255"},"modified":"2015-06-01T14:51:14","modified_gmt":"2015-06-01T18:51:14","slug":"planning-under-uncertainty-regime-shifts-resilience-and-innovation-in-urban-ecosystems","status":"publish","type":"post","link":"https:\/\/www.thenatureofcities.com\/TNOC\/2013\/01\/22\/planning-under-uncertainty-regime-shifts-resilience-and-innovation-in-urban-ecosystems\/","title":{"rendered":"Planning Under Uncertainty: Regime Shifts, Resilience, and Innovation in Urban Ecosystems"},"content":{"rendered":"

Cities face unprecedented challenges. \u00a0Global environmental change is placing increasing pressure on ecosystem functions and their ability to support human activities. \u00a0The exponential growth of human activities is a key driver of such change, so much so that Planet Earth has certainly entered a new Epoch\u2014the Anthropocene<\/a>, in which humans have as much influence as nature itself (Steffen et All 2007<\/a>).<\/p>\n

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The Anthropocene (Steffen et al 2007<\/a>). The term Anthropocene suggests that the earth has now entered a new epoch. Over the last 50 years, human activities have accelerated a range of key trajectories, as is clearly visible in the 12 indicators charted between 1750 and 2000. Some activities were not present before 1950; for others, the rate of change increased sharply after 1950.<\/figcaption><\/figure>\n

Urban regions pose enormous challenges to ecological and human well-being from local-scale atmospheric and water pollution to global-scale phenomena such as climate change threatening ecosystem’s capacity to deliver important ecological services (Alberti 2010<\/a>). \u00a0At current rates of urban growth, expected global land cover change will result in significant loss of habitats in key biodiversity hotspots (Seto et al. 2012<\/a>). \u00a0Urban regions are also the place where the majority of the human population will face the potential consequences of expected irreversible changes in climatic, hydrological, and ecological regimes such as flooding, droughts, sea level rises (Figure 1).<\/p>\n

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Extreme Events Source: Mosaic by Michal Russo. Photos: fire: Maxim Gusakov, fotopedia.com; flood: Marco Dormino, fotopedia.com; wind: http:\/\/freeaussiestock.com; droughts: suburbanbloke, fotopedia.com.<\/figcaption><\/figure>\n
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Beach community after Hurricane Sandy. Photo: Mark Olsen (USGS).<\/figcaption><\/figure>\n

Rapid modifications of biophysical systems have the potential to trigger regime shifts<\/a> (see below)\u2014abrupt and irreversible changes\u2014that will have significant consequences for human health, access to resources, human safety, security, and overall human wellbeing (Rockstr\u00f6m et al. 2009<\/a>). \u00a0Researchers have found that the likelihood of regime shifts is higher in ecosystems where humans have reduced their resilience by modifying biogeochemical cycles, altering hydrological regimes, reducing biodiversity, and changing the magnitude, frequency, and duration of disturbance regimes (Folke et al. 2004<\/a>). Potential regime shifts\u2014from climate change and flooding to water pollution\u2014pose enormous challenges to the stability of urbanizing regions and make them vulnerable (Miller et al. 2010<\/a>). \u00a0The recent Hurricane Sandy<\/a> and the less recent but tragic Katrina, along with the Japanese tsunami, clearly illustrate the unexpected shocks cities face in the next decades.<\/p>\n

How can cities navigate through such uncertainty and make robust decisions to ensure human wellbeing over the long term?<\/p>\n

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Regime shifts are large, abrupt, persistent changes in the structure and function of a system. An external shock can trigger a completely different system behavior, here represented by the ball moving into a new regime. But regime shifts also depend on slow changes in external drivers and internal feedbacks\u00a0that change the domains of attraction of the regime: from a resilient state represented in the figure by the dotted line to a less resilient state represented by the continuous line. The resilience of a state corresponds to the width of a stability pit. The loss of system resilience changes the thresholds that push the system into a new regime.\u00a0Definition: Biggs, R., T. Blenckner, C. Folke, L.J. Gordon, A. Norstr\u00f6m, M. Nystr\u00f6m, and G.D. Peterson. 2012. Regime shifts. In: Sourcebook in Theoretical Ecology. A. Hastings and L. Gross, editors. University of California Press, Berkeley\u00a0Photos: earth: woodleywonderworks; fire: Maxim Gusakov,fotopedia.com; flood: Marco Dormino, fotopedia.com; wind: http:\/\/freeaussiestock.com; droughts: suburbanbloke, fotopedia.com.<\/figcaption><\/figure>\n

The Challenge<\/strong><\/p>\n

At the core of the challenge we face is the inevitable uncertainty of dynamic coupled human-natural systems (Liu et al. 2007<\/a>). \u00a0Both ecosystems and societies experience continuous fluctuations in their structure and function. \u00a0Occasionally, change is punctuated by sharp shifts: abrupt transitions to an alternative state with significant implications for system function and dynamics (Scheffer et al. 2001<\/a>, Scheffer et al. 2012<\/a>). \u00a0Scientists have documented examples of regime shifts<\/a> for quite some time. \u00a0More recently they have described several examples in urbanizing regions (i.e. urban lakes, invasive species, floods), but we still do not fully understand the significance of such dynamics.<\/p>\n

Urban ecosystems are highly complex. \u00a0Change and evolution in such systems emerge as interacting agents engage in simple behaviors. \u00a0Uncertainty and the likelihood of surprise are driven by the complex interactions among ecological and social drivers and their unpredictable dynamics (Alberti 2008<\/a>).\u00a0 In urban ecosystems feedback mechanisms that operate between ecological and human processes can amplify or dampen changes, and thus regulate the system\u2019s response to external pressures. \u00a0For example, land cover change and rapid loss of tidal marshes coupled with the hydrological and ecological changes associated with the development of hard flood control structures (e.g., dikes, dams, levees, groins, seawalls, and storm water) increase system vulnerability to extreme climate events and prompts more demand for flood-control infrastructure.<\/p>\n

Extreme Climate Events<\/strong><\/p>\n

All around the world, extreme climate events are becoming normal when compared to historical records. \u00a0Climate scientists predict more frequent hot days, heavy precipitation, high-speed winds, and a likely increase in hurricanes (in the United States and the Caribbean) and flash floods (e.g. in East Africa), with significant consequences for human and ecological wellbeing (figures below, IPCC 2012<\/a>).\u00a0 Economic losses from climate-related disasters have increased, with large variations across places and years (below, IPCC 2012<\/a>). \u00a0Global losses due to the weather- and climate-related disasters reported over the last few decades mainly reflect the monetized direct damages to assets, and are not distributed equally. \u00a0Since 1980, estimates of annual losses have ranged from a few billion US dollars to over $200 billion (in 2010 dollars), with the highest value for 2005, the year of Hurricane Katrina (IPCC 2012<\/a>).<\/p>\n

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Projected changes in precipitations.\u00a020-year return values of the annual maximum 24-hour precipitation rates (IPCC 2012<\/a>).<\/figcaption><\/figure>\n

\"\"For a recent IPCC special report, \u2018Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation\u2019 (SREX),<\/a> 220 scientists collaborated for 30 months, looking at historical trends and projected trajectories to assess current frameworks and strategies.\u00a0 Their report points out that existing measures for managing risk and adapting to change need to be improved dramatically to face projected extremes.<\/p>\n

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Projected changes in temperatures (in \u00b0C) in 20-year return values of the annual maximum of the daily maximum temperature (IPCC 2012<\/a>).<\/figcaption><\/figure>\n

\"\"When multiple phenomena with uncertain trajectories\u2014for example, storm surges and power outages\u2014affect the function of cities simultaneously, the element of surprise can be enormous.\u00a0 Suddenly, resources and activities that everyone takes for granted, such as mobility or an energy supply, are unavailable, causing ripple effects<\/a> on people\u2019s safety and wellbeing.<\/p>\n

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Regional Distribution of Climate Disasters. Weather- and climate-related disaster occurrence and regional average impacts from 2000 to 2008 (IPCC 2012<\/a>).<\/figcaption><\/figure>\n
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Losses from Disasters (1980-2010). Overall losses and insured losses from weather- and climate-related disasters worldwide (in 2010 US$) (IPCC 2012).<\/figcaption><\/figure>\n

Climate scientists did predict<\/a> that given the expected increase in extreme events such as hurricanes, the subway tunnels in New York could flood as they did during Hurricane Sandy, but far less predictable were the many interactions with rail and road closures and the potential consequences of the shifting mobility patterns of thousands of city dwellers, especially since power outages and other system failures were simultaneously limiting the access to food supplies and drinking water.<\/p>\n

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Submerged Costal Metro Areas (Boston). This map, first published in the New York Times illustrates the potential impacts of climate change on costal metro areas. For example, 86% of Cambridge and 37% of Boston land area will be flooded in the next centuries (100-300 years) based on the estimate Sources: Remik Ziemlinski, Climate Central; U.S. Geological Survey; National Oceanic and Atmospheric Administration; U.S. Fish and Wildlife Service.<\/figcaption><\/figure>\n

By 2030, many coastal cities are likely to face raising waters at least 4 feet above the high-tide line due to storm surges and sea level rise (Climate Central 2012<\/a>). \u00a0A recent report by Strauss et al. (2012<\/a>) estimates that urban areas and their communities are highly vulnerable to sea levels rising anywhere from 0 to 6 m above mean high tide. \u00a0They found important threat levels: 22.9 million Americans live on land within 6 m of the local mean high tide.<\/p>\n

The future of Planning<\/strong><\/p>\n

Strategic decisions about urban infrastructure and growth management are based on our assessment of the past and our expectations for the future. \u00a0How we think about the future has significant implications for the choices we make and the decision-making process we apply. \u00a0Traditional approaches to planning and management typically rely on predictions of probable futures extrapolated from past trends.<\/p>\n

However, long-term trends are increasingly unpredictable given the complexity anduncertainty of coupled human-natural systems. \u00a0Predictive models that are designed to provide accurate assessments of future conditions can only account for some of the interactions between highly uncertain drivers of change and the surprising, but plausible, futures over the long term. \u00a0Important progress has been made in complex modeling, and improved simulation and computer power have allowed us to process quite astonishing amounts of data; still, our models are constrained by our limited knowledge, unverified assumptions, and short-sighted mindsets.\u00a0<\/strong><\/p>\n

Myths in Planning<\/strong>\u00a0<\/strong><\/p>\n

To address the inherent uncertainty of coupled human-natural systems, we need to expose some common myths in urban planning. \u00a0I expand the discussion of the myths in a chapter in my forthcoming book Cities as Hybrid Ecosystems<\/a>\u00a0<\/em>(2014).<\/p>\n

Stability: Thresholds remain constant over time, and thus are predictable.<\/em><\/p>\n

Planners have long assumed that systems are stable: that they return to equilibrium when confronted with external disturbances. \u00a0Steady state<\/em> is a condition in which nature exists at or near a persistent equilibrium.\u00a0 The steady-state paradigm holds that disturbance can be controlled and that by using an optimization strategy, systems can achieve sustainable carrying capacities.\u00a0 Within this perspective, thresholds that would produce change to a new state (i.e., a different equilibrium) remain constant over time, and are predictable and avoidable.<\/p>\n

But this isn\u2019t the case. \u00a0Coupled human natural systems may exhibit nonlinear responses to perturbations. \u00a0There can be more than one stable regime. \u00a0Both the position of a threshold along a driving variable and the depth of the basin of attraction can change. \u00a0Resilience is a dynamic property. \u00a0In coupled human natural systems such as cities, reciprocal influences between system shifts in both the ecological and social systems may occur (Walker and Meyers 2004<\/a>)<\/p>\n

Optimality:\u00a0There is an optimal resilient urban pattern and type of infrastructure.<\/em><\/p>\n

The idea of optimality\u2014that one can find the optimum among a set of possible alternatives given a set of conditions\u2014is a direct consequence of the steady-state paradigm. \u00a0Planners come to assume that an optimal solution exists. \u00a0Decisions based on seeking the optimum assume that we can quantify risks. \u00a0However, in the presence of irreducible uncertainties, we encounter multiple plausible futures whose relative probabilities are unknown. \u00a0The farther we look into the future, the more the uncertainty increases\u2014and it may increase even more with new understanding from advancement in scientific research. \u00a0For systems to function in an uncertain environment, robustness rather than optimality is a more appropriate target for planning and decision-making.<\/p>\n

Transferability:\u00a0What is resilient in one region and at one scale is resilient in other regions and at other scales.<\/em><\/p>\n

Many planning strategies are based on the assumption that what is resilient for a specific system function, at one scale, and in one region, is resilient for other functions, at other scales and in other regions. In complex social-ecological systems, multiple regime shifts may occur in multiple biophysical (climate, hydrology, biogeochemistry) and human (social, economic, and political) domains at multiple scales. \u00a0Furthermore in evolving systems, changes in scale influence resilience (Walker and Meyers 2004<\/a>). \u00a0Increasing the scale of urban systems may expand resilience by adding a diversity of ecosystem types, they depend upon, but urban expansion may increase the relative costs and impacts of maintaining urban activities on a larger scale. \u00a0If planners focus on the resilience of a specific subsystem, at a specific scale, that may cause the system to lose resilience in other ways. Instead, to maintain resilience we must focus on maintaining adaptive capacity and coping with uncertainty.<\/p>\n

Adaptability: We can maintain resilience by adapting our current institutional<\/em> frameworks.<\/em><\/p>\n

Human and natural systems have evolved through change, adaptation, and extinction. \u00a0But researchers in separate domains have studied of how human systems and natural systems adapt.\u00a0 As a result, we do not fully understand how coupled<\/span> human-natural systems evolve and adapt and what the limits are to their adaptability. \u00a0Adaptation planners are assuming that we can maintain resilience by adapting our current institutional frameworks. \u00a0In fact a co-evolving paradigm may require reconfiguring current planning frameworks and fundamentally transforming current institutions for managing our cities.<\/p>\n

The Myth of a Resilient Urban Pattern<\/strong><\/p>\n

Evidence that urban planning subscribes to such myths is provided by the dominant idea and search in planning for an optimal resilient pattern of urbanization. \u00a0The idea of an \u201coptimal pattern\u201d is based on the assumptions that thresholds remain constant over time, that they can be detected and predicted, and that what is resilient in one region and at one scale is resilient in other regions and at other scales. \u00a0Furthermore, adaptation planning is grounded in the idea that we can maintain resilience by adapting our current institutional frameworks.\u00a0<\/strong><\/p>\n

Building on the emerging evidence in urban ecology, I challenge the hypothesis that a shift in the pattern of urbanization toward a single \u201coptimal\u201d pattern is a desirable objective that will ensure resilience (Alberti, forthcoming). \u00a0I argue that no single pattern is consistently more resilient than another. \u00a0Resilience depends on variable biophysical and socio-economic conditions across regions and scales.\u00a0\u00a0<\/strong>Optimizing one function at one scale may increase the vulnerability of the whole system.<\/p>\n

In my new book Cities as Hybrid Ecosystems<\/em><\/a>, I advance the hypothesis that to enable resilience, it may be necessary to create a diversity of urban patterns within and across urbanizing regions.<\/p>\n

Resilience in Urban Ecosystems<\/strong><\/p>\n

The resilience<\/em> paradigm recognizes the existence of multiple stable states and focuses on adaptation as a strategy to maintain system function. \u00a0Resilience is the capacity of a system to absorb disturbance and reorganize while undergoing change so it can retain essentially the same functions, structures, identity, and feedbacks (Holling 1973<\/a>). \u00a0In coupled human-natural systems, resilience emerges from the interactions of human and ecosystem drivers, patterns, processes, and functions (below).<\/p>\n

My colleague John Marzluff and I together with my team at the Urban Ecology Research Lab (UERL)<\/a> are currently working toward a new transdisciplinary network to advance scientific understanding of regime shifts, resilience and adaptation in urban ecosystems. \u00a0This network aims to inspire, generate, and facilitate new modes of interaction and collaboration among diverse members of the scientific communities and practice to produce a new level of synthesis<\/em> of existing knowledge, identify research priorities<\/em>, and establish new empirical evidence<\/em> on the relationships between ecological resilience and human wellbeing in urbanizing regions.<\/p>\n

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Resilience in Urban Ecosystems (Alberti, forthcoming<\/a>). Credit: Marina Alberti<\/figcaption><\/figure>\n

Evidence emerging from the study of complex systems can provide insights for planning and management. In a recent paper in Science, Sheffer et al. (2012)<\/a> suggest that system shifts may result either from unpredictable external shocks or from critical transitions. \u00a0Drawing on two separate lines of investigation\u2014on complex networks and on the proximity of critical thresholds\u2014they suggest that both the heterogeneity of the components and their connectivity affect the stability of systems on the long run. \u00a0By building on such observations in ecological systems, we can develop hypotheses about the fragility and robustness of coupled human-natural systems and test them in urban ecological systems.<\/p>\n

Patterns of Resilience<\/strong><\/p>\n

I suggest that the diversity of urban patterns (e.g., centralization, building density, road connectivity) may control the resilience of urbanizing regions, because it is the diversity of processes alternative patterns can support that expands the region\u2019s capacity to adapt to a variety of conditions that can emerge in the future (Alberti, forthcoming<\/a>). \u00a0In the most recent examples of extreme climate events that have tested the resilience of large urban regions across the world, the greatest surprises are in what worked: the countless ways in which unintended functions and flexibilities created by an imperfect and redundant urban infrastructure (i.e., transportation systems) provided alternatives and ways out. \u00a0When the subway floods unexpectedly and shuts down for a week, many interconnected activities will jolt, and mobility patterns will shift suddenly. \u00a0It is under these circumstances that we come to see how heterogeneous and modular the city networks and systems actually are. \u00a0 Examples are provided by the power of real-time communication technology such as cell phone networks, by on-line retailers\u2019 delivery systems, and by the redundancy and flexibility of multiple transportation and infrastructure systems.<\/p>\n

Critical transitions pose great challenges and opportunities. \u00a0Innovation and creativity are important ingredients of resilience; at the same time they are often triggered by the same forces that drive critical transitions (Allan et al. 2010<\/a>). \u00a0Critical transitions offer unique opportunities for positive transformation and generate he seeds for cities to become more resilient and innovative. \u00a0When new frames of reference and new constraints emerge, they require people and planners to see opportunities and risks they have never experienced before. \u00a0Such new frameworks highlight problems and unequal distributions, and expose tradeoffs and synergies; thus they expand the boundary conditions of what is possible and desirable.<\/p>\n

From Resilience to Transformation<\/strong><\/p>\n

Resilience is about avoiding system shifts. \u00a0But persistence is not always desirable. \u00a0Many undesirable states, such as degraded ecosystems or social inequalities, may be quite resilient. \u00a0So while resilience planning focuses on predicting and adverting potential thresholds and system shifts, moving towards a desirable state requires transformation (Walker et al. 2004<\/a>).<\/p>\n

Resilience in coupled human-natural systems requires transformation towards what is desirable (Folke et al. 2010<\/a>, Ernston et al. 2010<\/a>). \u00a0This implies addressing the diversity of human values and the existence of conflicts. \u00a0A co-evolving<\/em> paradigm may be more appropriate. \u00a0This view focuses not only on unpredictable dynamics in ecosystems, but also on institutional and political flexibility for learning, reconfiguring problem solving frameworks, and devising innovative policies. \u00a0Instead of seeking to reduce uncertainty, planners and decision makers will need to identify and adopt robust strategies that will be appropriate under a broad range of alternative futures.<\/p>\n

Future policies and management practices will succeed or fail based on their ability to take into account the complexities and uncertainties of these systems. \u00a0When policies aim to stabilize the ecological system or eliminate its variability, the inevitable outcome is collapse (Carpenter and Gunderson 2001<\/a>). \u00a0This is where scenario building can be valuable, as both a systemic method and a framework to expand our ability to think creatively about the future by focusing on complexity and uncertainty (Peterson et al. 2003<\/a>). \u00a0Rather than focusing on accurately predicting a single outcome, scenarios let us examine the interactions between various key uncertain factors that will together create alternative futures. \u00a0Using a series of hypothetical future scenarios, we can assess the robustness of alternative strategies.<\/p>\n

Local governments need to make important decisions about land use management and investments in infrastructure that can influence the direction of urban development in the near future.<\/p>\n

I suggest five principles for planning under uncertainty towards enabling resilience and innovation in urban ecosystems (Alberti, forthcoming<\/a>):<\/p>\n