“I suggest that most post-industrial cities are hybrid and unstable,” urban ecologist Marina Alberti states in her book, Cities That Think Like Planets. “We can drive them to ecological collapse.”
A professor of urban design and planning and director of the Urban Ecology Research Lab at the University of Washington, Alberti explains how cities avoid such a fate and instead build resilience to what has been their contribution to a slow and significant change in land use, population and climate.
Cities will produce a response. How well depends on how we shape it in the image of how we would like urbanity to shape us (by 2030, urban land will increase by 1.2 million square kilometers, three times the land area of 2000). It may be a bumpy ride.
“We can consciously steer them toward outcomes we desire, i.e. resilience,” she continues. “The way to do this is not yet clear. But, cities around the world are investigating diverse avenues to do so. Cities have a vast store of innovation capacity.”
Resilience theory is based in the idea of allowing for uncertainly when making decisions. Also, it calls for recognizing when thresholds have been crossed into what Alberti and other leading urban ecologists call a hybrid “socioecological” system.
“Hybrid urban ecosystems form as a result of the interactions among human and natural flows of information, energy and materials.”
For instance, geographically dispersed, random, highway fueled development has resulted in microclimates such as heat islands and altered stormwater function leading to issues like algal blooms for coastal cities.
Cities will have to learn to be nimble and innovative, understanding that changing back to a perfect state of nature is unlikely.
The artificial reef system in Venice, Italy, for example, is a response to rising seas that is a hybrid approach. Green corridors in cities are another example of a design choice to provide habitat for wildlife and mitigate stormwater flow, reduce heat, cool the atmosphere and absorb pollutants. The fine print: May require communities to rethink the time scale of its decisions.
“Although evolutionary biologists recognize (that reorganizing leads to renewal), ecologists see the hybrid nature of urban ecosystems as a threat to stability and resilience," she observes.
Urban ecologists are researching how species ‘evolve and change’ to the pressures of regime change.
“One of the earliest examples of urban adaptation is the dark-eyed junco (sparrow). In San Diego, it has adapted its morphology and behavior”—shorter wings and tails and bolder behavior than their forested cousins. Selection pressures from the hot environment in cities and new edge effects from infrastructure like dams affect fish reproduction or mice populations boom improving the odds of survival for pests like ticks.
We have altered the natural, but not always in negative ways. Cities add to the natural system; they also flourish for economic reasons and serve human needs.
Green infrastructure is the other side of the eco evolutionary coin.
“Eco-evolutionary feedbacks imply that populations modify their environment, and that environmental changes influence the evolution of populations. Cities evolve as the outcome of myriad interactions.”
How would Cleveland adopt this thinking in guiding its pursuit of climate resilience? What role could we see science and imagination playing in how we engineer moving water and removal of waste, for example.
After all, there’s a lag time in regime change, by the time it bubbles up to a community response. Expensive grey infrastructure, like deep tunnel intercepts, hold at bay the storms of today, but it could lock us into bigger and more expensive versions of the same in the future. A hybrid system is multi layered, resilient and nimble.
Loss of forest and green space cover is a slow variable, and changes to nitrogen concentration in the soil altering ecosystem function is a fast variable. Urban planning has a bias toward the fast variable. Alberti has shown in studies in Seattle, the suburban and exurban fringe needs time to accumulate biomass to generate beneficial (retention and input) nitrogen cycles. Other studies have shown that the heterogeneous (dispersed) nature of ecosystems in cities force living things to be more adaptive to change than organisms would have to be in an undisturbed forest. It’s counter intuitive but it suggests what Alberti and others have found—that disconnected systems are able to respond to change. If only humans develop the ‘recognition software’ in time. Perhaps it will be built on a platform of how nature responds.