Which picture represents the boundary between an urban and non-urban area?
If you answered with any image, you’re not wrong. How we define urbanization is highly variable. It’s context-specific, scale-dependent, and the topic of a rich and ongoing discussion.
For the sake of comparing apples to apples, we strive to maintain a certain level of consistency when designing urban studies: we aim to measure a location’s degree of urbanization with metrics of impervious surface coverage, density of human population, and so on. This is how we try to distill the messiness of ecology into data. It’s a noble goal- difficult, but with resounding benefits if done well.
But for the rest of this blog post, let’s embrace that messiness. Let’s think beyond measures of urbanization and, instead, ask: are there any corners of the Earth that haven’t been touched by the hand of urbanization in some way? Many of us consider cities to be insular bubbles of urban characteristics, but what if the real bubble is the globe? Or is even a worldwide scale too narrow?
Contemplate the following examples of how urban-ness can extend past the city limits.
Resource extraction
Like many places, Switzerland does not produce any crude oil and instead has to import all of this resource to fuel Zurich’s buses and Geneva’s trains. Oil flows in from around the world: about half of the country’s needs come from African countries including Nigeria, Libya, and Egypt, while the remainder is sourced from Mexico, the US, Kazakhstan, and other nations. Since the Swiss rely on this foreign-sourced product to make their cities run, can one argue that its importers’ oil sands are a cog in the urban machine? Think beyond oil: wood from Amazonian trees and the mining fields of rare earth minerals used in smartphones are also caught up in the grey area between urban and non-urban.
Garbage
Humans generate a lot of trash. Some ends up in the oceans, some in landfills, and some even ends up in space where it can cause major problems for satellites. Much of this trash is produced by people living in cities. If the Great Barrier Reef effectively acts as a depository for your water bottle, does it take on a role that propels it into the urban metabolic system? Furthermore, there’s a chance that your water bottle will break apart and end up clogging the gills of a fish that is consumed by a pelican and given a tour up and down the rungs of a food web. Does that semblance of urbanization affect each of these participants too?
Fuel emissions
Perhaps the easiest way to visualize the sweeping influence of urbanization is to imagine how exhaust fumes from cars make their way into the atmosphere. As we well know, the buildup of certain anthropogenic emissions such as methane have contributed to the greenhouse effect. The resulting global climate change, a process whose influence is becoming increasingly visible, is evicting polar bears from melting ice caps, shifting the geographic layout of biomes, and so on. You can probably tell where I’m going with this: if urban-dwellers are the ones who are largely responsible for these greenhouse gas emissions, is climate change acting like a missionary that is spreading the influence of urbanization?
If that was too far a stretch, think about the trees that graciously inhale another major anthropogenic emission- carbon dioxide. Those trees are taking in a byproduct of urbanization.
So, how can we draw the line between urban and non-urban? Once something is influenced by urbanization in some capacity, can it ever return to its former state? Is there a difference between adaptation to anthropogenic stressors and adaptation to urban environments? Leave your thoughts in the comments!
Many thanks to University of Toronto professor Matti Siemiatycki, who inspired this post with his lecture at the 2018-2019 Center for Urban Environments seminar series.
Featured image (top): John Goldsmith / Road off the cliff, Covehithe /
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