Sunday, April 27, 2008

One city, two city, three city, four

Do you live in a Megalopolis? If you don't now, you likely will, according to Nancy B. Grimm, Arizona State University Urban Ecologist. In an article in Science, 8 Feb. 2008, titled "Global Change and the Ecology of Cities" Grimm et al. provide a review of our expanding urban landscapes. Five key areas of change are addressed: land use and cover, biogeochemical cycles, climate, hydrosystems, and biological diveristy.

Seattle marching south

What are expanding urban landscapes?
Nothing you or I haven't seen: a semi-rural or peri-urban area built into a bedroom community, for example. While existing cities get bigger by sprawling outward, small towns and even undeveloped areas are likewise being populated, built up, and eventually gobbled up by the nearest metropolitan area. A spattering of towns growing up betwixt expanding major metropolitan areas means they'll eventually meet up geographically -- it's inevitable. Connect the dots and you've drawn a burgeoning Megalopolis. It's not happening... It has happened. LA. The Bay area. The I-5 corridor from Seattle to Portland (which could be stretched from Vancouver, B.C., to Eugene, OR). Phoenix to Tucson along I-10 (even the local skeptics can't argue this one). Dozens more dots in the midwest and east are working their way together, too. That's just the U.S. -- as the article points out, and demographic statistics support, this is a global trend in the third & second world, and developed countries alike.

Planet-wide, this scene gives rise to a powerful trend: an inverse relationship between urban and rural population growth. More people living in bigger cities.

How are megalopolises beneficial and detrimental?
They may exacerbate the effects of global climate change locally with the heat island effect. This has and will likely continue resulting in increased energy demands for cooling; this energy use in turn contributes to the causes of global warming. Subverted, diverted and overly allocated waterways serve increasing demands of these mega cities, turning riparian habitats into non-functional ecological systems. Megalopolises serve as hot spots for the introduction of non-native species. And due to altered availability of resources, such as grains vs. insects as bird food, urban wildlife populations undergo radical population shifts.

On the bright(er) side, city dwellers often have a lighter ecological footprint per person given the more compact living style , shorter commutes to grocery stores and other goods, reduced-pollution forms of transit, etc. One caveat to this: rural developments often have no self-sustaining industry of their own, requiring inhabitants to commute by necessity for their work, services, or even goods.

One very neat idea this article mentions is the analogy of a city as an organism: "...takes in food and other required resources, and releases wastes into the environment." The continual grind of the "urban metabolism" -- consumption and waste -- is a potentially useful, though scientifically debated, tool for quantifying ecological impact of a metropolitan area. Pretty neat!

A megalopolis in the making

When I first arrived in Arizona, I was car-less and lived/worked at a research center between Phoenix and Tucson. It was more than a 25 minute drive from the nearest city; a nearby "town" sat two miles away, with maybe four buildings, a population of perhaps 1-2K, and one traffic light. I lived at the research center -- a secluded island surrounded by a sea of Native American reservations, agriculture, pecan orchards, and dormant land. That was 2003.

Today the surrounding land is covered in miles of homes. You've seen it: a sea of new developments provisioned with fire stations and pharmacies, mega-grocery stores, schools stocked with teachers and already overflowing with children. New strip malls boast a service for every amenity. You'd think it'd been there forever, marching as it does right up to the edge of the agricultural plots at our facility. It’s presence is a challenge.

No fewer than a dozen new traffic lights in the nearby town
now regulate tens of thousands of people, their cars, their needs.
In this short time, I've witnessed the birth of
an organism...with an urban metabolism.

With the ailing economy, at least one of the developers has gone bankrupt -- boom and bust, just like in the gold rush days of the nearby hills. To sell the homes, I understand free swimming pools or granite counter tops are being thrown in as a perk. Meanwhile, perfectly good inner-city re-sale homes continue to sit empty. Do we really need the superfluous developments? Will anyone go homeless if they aren’t built? When the economy rebounds, when new homes are once again created like card houses overnight, one thing seems certain: if you build it, they will come.

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