Newswise — New research by visiting Boise State University professor of economics Michail Fragkias could help shape how major cities are built and managed in the coming decades.
More than half the world’s population currently lives in cities, and an additional 3-5 billion more are headed that way by the end of the century. This growth has led to increased interest in finding ways to meet energy demands, control greenhouse gas emissions and ultimately achieve global sustainability.
It is a long-held assumption that large cities benefit from economies of scale. A higher concentration of residents, shared infrastructure and increased economic activity lead to innovation, efficiencies and lower-than-average energy consumption.
Or does it? Data collected by Fragkias and his team of co-researchers brings that last assumption into question.
“We find that for the time period of 1999-2008, CO2 emissions scale proportionally with urban population size,” the study notes. “Contrary to theoretical expectations, larger cities are not more emissions efficient than smaller ones.”
Findings are detailed in a paper titled “Does Size Matter? Scaling of CO2 emissions and U.S. Urban Areas,” recently published in PLOS ONE. Authors are Fragkias, José Lobo of Arizona State University, Deborah Strumsky of University of North Carolina-Charlotte and Karen C. Seto of Yale University.
Cities consume more than 66 percent of the world’s energy and generate more than 70 percent of global greenhouse gas emissions. With the global population expected to hit 10 billion by 2100, with nearly 90 percent living in urban areas, understanding the efficiencies of cities is critical.
Toward that end, researchers looked to a biological scaling model that states that the larger the animal, the more energy efficient that animal is. Specifically, for every 1 percent increase in an animal’s size, there is a corresponding 0.75 percent increase in its metabolism.
Researchers wondered: Would this model translate to social systems?
To find out, Fragkias and his co-authors looked at data from metropolitan and micropolitan statistical areas. Because data on actual energy use is not widely available for urban areas, researchers used CO2 emissions as an indication of energy consumption.
Since each city differs widely in population, number of buildings, types of businesses, etc., there is no “average” city for researchers to base their work on. But by applying nature’s scaling laws across a large spectrum of population sizes, researchers had a meaningful way of capturing effects on CO2 emissions.
They expected to see dramatic drops in CO2 emissions for megacities like New York, Los Angeles and Chicago. Instead, they found that each area pretty much mirrors the others.
“Showing that larger cities are not more emissions efficient is really valuable to those who design urban strategies and policies for a country. Our study clearly points to the importance of the “mass” of the city as measured by population size. But we have to remember that while population size is a good indicator of urban features like CO2 emissions, it is not fully circumscribing urban properties.” said Fragkias.
Study co-author Seto, emphasized that the study doesn’t mean that larger cities cannot be more efficient. Instead, it shows that increased population does not automatically equate to increased efficiency.
“Here’s another way to think of it,” she said. “If you have an inefficient city, one that is car-based and characterized by leapfrog low-density development, tripling that city’s population isn’t going to make it more efficient. You’ll just have more of the same. In contrast, if your city has ‘good bones’ — it starts off being walkable, with mixed land use, accessibility and energy efficiency — then small and big will both be efficient.”
In other words, once you take the size of a city’s population into account, the study suggests that cities that become more efficient as they grow (think of New York, Tokyo, Copenhagen, Hong Kong, as possible examples) will have something else going for them.
And there still may be incentives for governments to promote larger cities. For instance, related research has shown that doubling the size of a city leads to about a 115 percent increase in innovation, research and development jobs and total wages. Cities also provide convenience, cultural amenities and other positive social factors, and many are working toward sustainability goals such as pollution abatement, poverty reduction and human well-being.
As the researchers state in their paper: “As (new) world cities continue to grow, it is important that policymakers consider the CO2 emission effects of urban size and contrast it to the effects of urban form, building materials and transportation network structure.”
Read the full paper at http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0064727.
About Boise State UniversityA public metropolitan research university with more than 22,000 students, Boise State is proud to be powered by creativity and innovation. Located in Idaho’s capital city, the university has a growing research agenda and plays a crucial role in the region’s knowledge economy and famed quality of life. In the past 10 years, the university has quadrupled the number of doctoral degrees, doubled its masters degrees and now offers 13 online degree programs. Learn more at www.BoiseState.edu.
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