Urban Bias: Justified?

How important is urban climatology, really? The question seems important as the field grows in size and scope, drawing in more and more resources. While certain statistics about the urbanization of the world are now widely known (e.g. that more than half the global population lives in cities, or that megacities are growing much faster than small cities or rural areas), there is also a danger that smaller municipalities will be outshone figuratively as well as literally by the bright lights of big cities, and that other worthy climate impacts will be overlooked in the process.

A post last year from Marshall Shepherd commented on one demonstrated aspect of “urban bias” in the context of forecast accuracy; specifically, he noted that weather reports in the media tend to focus on urban areas to the exclusion of everywhere else, and that this focus is disproportionate even to their larger populations. I would argue that to a considerable extent this is a consequence of media navel-gazing, a sort of availability bias. After all, urban bias makes an appearance in other fields as well — how many TV shows are set in New York City, home to just 2.6% of the country’s population?

Of course, this blog being titled what it is, it’s worth noting why cities are the object of such intense newfound attention. Much of it is well-deserved, a rightful recognition of the significant concentrations of people and assets that urban areas contain; the ten largest metropolitan areas in the US produce 35% of the GDP despite having only 26% of the population. There are also an enormous variety of interesting interactions on a variety of scales, which are just beginning to be able to be studied systematically (i.e. climatologically) thanks to advances in computing power. Cities are also often positioned on rivers, along coastlines, or in valleys, adding an extra topographic level of complexity to their microclimates. As a result of all of this, climate in a large and diverse metropolitan area like New York can span a wide range of temperatures, not to mention precipitation, etc. As shown in the figure below, the annual-average temperature at LaGuardia Airport is equivalent to that in central Missouri, while the temperature in the southern Catskills is like that of Minneapolis, 10 deg F colder and 400 miles north.

Lines marking the latitude at which the annual-average temperature equals that of the southern Catskills (blue) and of LaGuardia Airport (red), the two temperature extrema of the New York City metropolitan area. Source: Own work (based on station data and CPC gridded dataset)

All fields of science seem to exhibit a tendency to stampede from topic to topic, leaving topics that are not fashionable sitting dust-covered on the side of the trail. This is unavoidable — part of human nature — but good to be aware of so that the most can be made of it in terms of building up understanding and impacts applications. For example, organizations like CCRUN have focused largely on the major cities of the Northeast, due to their having the dedicated funds and personnel for climate issues. At meetings I’ve attended there have been discussions around the possibility of working with small and medium-size cities, though here (as elsewhere in the country and indeed the world) such work is hindered by the inherent difficulties of scale, the greater number of municipalities and their smaller discretionary funds being chief among them. While 55% of people currently live in cities, only 23% live in cities of at least 1 million. In fact, in 2030 rural areas will still account for 40% of the global population. An additional positive outcome from the push to improve urban climatology would be a conscious downward movement of resources and methods to these smaller localities. Whether by direct focus or extrapolation from results for larger places, small cities, towns, and villages deserve to not be forgotten even in an urbanizing world.