February 8, 2006
Green Infrastructure Lets Nature Help Carry the Load of Our Cities
Department of Urban Studies and Planning,
California State University, Northridge.
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Southern California desperately needs investment in infrastructure. Governor Arnold SchwarzeneggerŐs proposed $222 billion infrastructure investment vision sets the stage for this discussion. However, we have come to a place, removed from nature, where we think of infrastructure rather narrowly. We plan to build with concrete and steel and asphalt, importing electricity and water, exporting waste and pollution, and relying increasingly upon the automobile to carry us about a landscape that we have segmented out into distant and disjointed uses.
But there is another form of infrastructure that we could just as easily and far more cheaply deploy to help carry the burden we place upon the land. Green infrastructure. The goods and services nature would dearly love to offer us, ours for the taking and only in exchange for an intelligent recognition of our ecological context, and a respect that is due the land.
Dark, heat-absorbing, impervious surfaces, namely roofs, roads, and parking lots, are the quintessential hallmark of urbanization. This often unmitigated fact has a range of significant and cumulatively detrimental effects on the ecological and bio-geo-chemical processes and functions that underwrite our cities and shape our inhabited world. We reduce the effective carrying capacity of the land by generating needless waste and pollution. This waste is not merely waste, but rather an actual increase in the costs we must incur in the form of the enhanced infrastructure needed to counteract our often unthinkingly expressed preferences. We choose NOT to live lightly upon the land, and then groan at the added burden our civilization must carry.
Conventional building practices result in increased ambient temperatures due to the proliferation of heat-absorbing surfaces. Urbanized regions can be 4 to 10 degrees Fahrenheit hotter than their surrounding countryside. This generates increased biological and material heat stress, a substantial part of which we could easily alleviate, at little additional cost. This also increases the load we place on our air conditioning systems, consuming electricity that we could very easily put to more productive uses. The higher temperatures also increase the formation of photochemical smog. And groundwater recharge is reduced, even as urban stormwater runoff is increased, due to a mindless proliferation in impervious surfaces.
Our sprawling patterns of urbanization force us to drive further and longer, to and from our multiple daily tasks, increasing traffic exhaust. Our freeway surfaces receive increased depositions of toxic dust and exhaust particles, building up through the year, nano-layer over nano-layer and quite invisible to our eyes, awaiting that first flush of the winter rains that will wash these toxins into our stormwater drains. Of course, this will require additional expenditures in water purification to maintain the quality of our water bodies.
The piece-meal and haphazard appropriation of lands for urbanization results in a needless fragmentation of natural habitats. The large-scale insertion of often non-native vegetation in the form of ornamental gardens shaped to mimic images imported from far away and long ago, the broad sweeps of synthetically maintained and copiously irrigated grass lawns, all come together to disrupt indigenous landscape ecologies and to interfere with the pulsing patterns of regional bio-geo-chemical processes. And so, without thought and without ill-intent, the land becomes more and more a receptacle for the toxic effluvia of our unconsidered urban lifestyles. All of which results, ultimately, in the more unequivocal separation of humans from nature. And in lots more of that expensive concrete and steel infrastructure stuff we need to live our lives.
With time and with technological modernization, our cities have come to rely increasingly on the bending of nature to our whim, This has lead to a corresponding reduction in our need, and so our willingness, to even think to adapt to the particulars of our environmental context. Rather than build in a vernacular, using climatically appropriate building materials and locally adapted dwelling types, we choose instead to impose our will upon the land, capitalizing on the apparent economic benefits of a mass-production mass-culture. Of course, we must then compensate for the ecological consequences of such choices through the increased use of air conditioning and heating, more of the personalized transportation infrastructure to support our lone commutes across sprawling landscapes bereft of localized neighborhood connectivity.
We choose to deny our ecological context, and impose instead our own production of place. But by denying our ecology, we come also to live more heavily upon the land. And at least some of the infrastructure we are now forced to build may have just as easily been avoided, without loss to quality of life and to our preferred lifestyles.
It doesnŐt have to be this way! We can let nature back into our cities, using intelligence, innovative materials, suitable tree species and native vegetation to lighten our tread. Three strategies from urban ecology: heat island mitigations, urban forestry, and impervious surface management, together provide many of the infrastructure benefits our contemporary society needs. Together, these strategies will considerably reduce air pollution and water pollution, significantly enhance our natural water supply, substantially strengthen connectivity across the rich and diverse habitats within which we dwell, while at the same time reducing the carbon dioxide emissions that mark our copious transfer of below ground carbon into the atmosphere, in the form of fossil fuels.
By integrating such green infrastructure measures into our planning, we would come, cumulatively, to reduce our ecological footprint, and, at the same time, to increase the effective carrying capacity of our land. If we intelligently deployed more green infrastructure as an integral element of the Governor SchwarzeneggerŐs proposed Strategic Growth Plan, we would need far less concrete and steel. Ensuring that the $222 billion investment being proposed for California is built around a green infrastructure core that takes account of ecological processes will result in substantially better returns on investment today, while ensuring a benefit stream that continues much further into the future. Green or gray, we get to choose.
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Ashwani Vasishth is an Assistant Professor in the Department of Urban Studies and Planning at the California State University, Northridge, and a member of the California Community Forest Advisory Council. His research is focused on the development of an ecosystem approach to integrative regional planning, and he can be reached at email@example.com , or at http://www.csun.edu/~vasishth .