Hot Journal, Hotter Cities

By Reid Ewing

Past columns have focused on three planning journals, Journal of the American Planning Association, Journal of Planning Education and Research, and Journal of Planning Literature. These journals ranked first, second, and sixth, respectively, in the reputational rankings of Goldstein and Maier ("The Use and Valuation of Journals in Planning Scholarship: Peer Assessment versus Impact Factors," JPER, 2010). They all have respectable impact factors, which measure how frequently the articles they contain are cited. Of 38 journals in the category of Urban Studies, JAPA ranked first in its 2012 impact factor, JPER ranked eighth, and JPL ranked 13th. But these aren't the only planning journals that academics read and practitioners should be aware of.

JAPA, JPER, and JPL are multidisciplinary. There are also specialized journals on the Goldstein and Maier list, and I will feature some of them in this and future columns. Housing Policy Debate, for example, ranked fourth in reputation among planners, Economic Development Quarterly ranked seventh, and the Journal of Urban Design ranked 14th. This column will introduce readers to another fine journal, Landscape and Urban Planning, which ranked 15th in reputation on the aforementioned list. LAND was second only to JAPA in its 2012 impact factor, and it ranked ahead of JAPA in its five-year impact factor, first of 38 journals.

LAND is more specialized than the journals usually featured in this column, focusing on landscape ecology, urban ecology, and landscape planning. LAND describes itself as an international journal, and indeed it is to a greater extent than is JAPA. A recent issue (Vol. 125) contains articles on thermal comfort in Damascus, Syria; nature restoration in Flanders, Belgium; habitat structures in Canberra, Australia; and park use by children in Montreal, Canada.

LAND has become a popular outlet for research on urban heat islands. UHIs are temperature differentials between urban areas and rural areas. They are caused by buildings, replacement of landscapes with infrastructure, use of utilities, and motor vehicle exhaust, among other factors. UHIs are distinct from climate change and global warming, though both are causing cities to get hotter. Most large U.S. cities are warming twice as fast as the planet, according to Brian Stone of Georgia Tech.

Impacts include increased energy consumption for space cooling, elevated emissions of air pollutants and greenhouse gases, compromised human health and comfort, and impaired water quality. The national cost of excess energy production necessary to compensate for UHIs is estimated to be about $10 billion annually. In addition,UHIs lead to an increase in ground-level ozone, with a corresponding increase in respiratory illnesses and mortality rates. Furthermore, UHIs may increase water temperatures, resulting in impairment of water ecosystems.

About half of the world's population currently lives in cities. Projections by the United Nations suggest that 60 percent of the world's population will reside in urban regions by 2030. High rates of urbanization mean increasing numbers of people exposed to UHIs.

There has been explosive growth in research on UHIs in recent years. Using the search engine Google Scholar and typing in "urban heat island" returns 26,900 distinct journal articles, book chapters, books, working papers, and professional reports, with 87 percent of them published since 2001. Limiting the search with the words "urban planning" still turns up 6,360 hits.

A recent LAND article on UHIs by urban planners Bumseok Chun of Georgia Tech and Jean-Michel Guldmann of The Ohio State University shows that open spaces, vegetation, building rooftop areas, and water sources strongly impact surface temperatures, and that spatial regressions are necessary to capture neighboring effects (see my April 2014 column for a discussion of spatial regression models). The authors use the "best" regression model to simulate the temperature effects of green roofs, greened parking and vacant lots, vegetation densification, and other greening strategies in the center of Columbus, Ohio.

The results demonstrate the potential of such strategies to mitigate UHI effects through design and land-use policies. Their model can also be used to assess other strategies for mitigating UHI effects, such as increasing the distance between buildings and capping building heights.

So as the planet heats up, it is reassuring that planners can do something to keep cities from heating up even faster.

Reid Ewing is a professor of city and metropolitan planning at the University of Utah and an associate editor of the Journal of the American Planning Association.

Resources

Image: Big buildings (and parking lots) sizzle on the researchers' map of downtown Columbus, Ohio, whereas natural areas are markedly cooler. Image courtesy BumSeok Chun.