With the commencing of the Copenhagen climate conference this week, it seems appropriate to bring the subject of climate change into the context of shrinking cities. More specifically, looking at potential impacts that could lead to major future geographic shifts in population that could lead to shrinking cities of the future.

The climate change effect that comes to mind in thinking about need for shifting populations is sea level rise. The map to the right shows the a map from the EPA that exposes areas vulnerable to sea level rise on the Gulf Coast, starting at a potential rise of 1.5 meters (~5 feet). Predictions from bodies such as the IPCC and the United State Global Change Research Program (USGCRP) range from 8 inches to 6.5 feet by the end of the century, but consensus is closer to 2-3 feet max. Such projections could, and in the case of New Orleans, already are creating migration patterns out of vulnerable areas. This shift will require planning responses with some parallels to shrinking cities, but more dramatic “busts” of currently booming cities are a greater correlating concern in a hotter and drier US southwest.

The possibility of cities like Phoenix and Las Vegas, who have experienced decades of excessive growth, are now looking at real possibilities of water shortages that could very well lead to their demise. As a 2007 article in Toronto’s The Star, entitled “Could climate change herald mass migration?” suggests:

“At first glance, the crises of the rust belt and the Southwest would seem unrelated. They are, in fact, inexorably linked. Each has what the other does not. In Phoenix, tremendous affluence; in Cleveland, and in Detroit, Toledo, Youngstown, Buffalo, Rochester, Thunder Bay and Sault Ste. Marie, abundant, near-endless water – in the Great Lakes alone, as much as 25 per cent of the world’s supply.”

The article suggests, that an increasingly mobile population that quickly moved to the sun belt might very well be packing their bags to head back to the rust belt! The human need for fresh water is what led to the location of every historic city in history, only in the last 100 years or so have we decided that it was a good idea

to build megapolises in the middle of the desert. I will restrain myself from a lengthy diatribe of unsustainable land use patterns (see photo I recently took flying over Las Vegas) and water use with a lack of concern for the consequences, but the point remains that it may soon come to an end.

Las Vegas sprawling into desert - Future vacant property?

The USGCRP map of the US shows projections of a drier west…could this lead the horse back to water?

More than likely technology will offer solutions, but they will cost. If the true externalities of building golf courses and swimming pools in the desert must be paid, then by the end of the century many cities will be facing the same problems of the Detroits and Clevelands of today. Either way, Toronto is looking at this as a potential opportunity and perhaps other Great Lakes cities should do the same. At the same time, growing cities in the deserts of AZ, TX and CA should be seriously considering how to better adapt to a warmer and drier future.