Smart Urbanization Could Reduce
Energy Use in Cities 25 Percent by 2050

In its most recent report, the Intergovernmental Panel on Climate Change (IPCC) estimated that urban areas are responsible for up to 76 percent of global energy use and generate about three-quarters of carbon emissions. The report, however, offered no suggestions on what cities should do about it.
 
In a new study co-authored by Yale F&ES Prof. Karen Seto, a team of scientists identifies the factors driving energy use in 274 cities worldwide, providing critical new insights into how different types of cities can reduce energy use — and more effectively mitigate the effects of climate change.
 
According to their findings, published in the Proceedings of the National Academy of Sciences, changes in urban planning and transportation policy can limit the increase in energy use in the world’s cities in 2050 by one-fourth — from a projected 730 exajoules under current trends to 540 exajoules. In 2005, urban energy use was about 240 exajoules.
This paper illustrates that there is a window of opportunity to affect how these cities develop and save emissions.
— Karen Seto
Cities located in developing countries would account for 86 percent of these energy savings through changes in building patterns and development intensity, including strategies that promote short commutes, public transportation, and a mix of land uses.
 
The study was led by Felix Creutzig, head of the Land Use, Infrastructures and Transport working group at the Mercator Research Institute on Global Commons and Climate Change (MCC) in Germany. Other co-authors included researchers at the University of Maryland and the Potsdam Institute for Climate Impact Research. Read the press release.
 
“We know that the growth of cities in Asia, Africa, and the Middle East is enormous and is happening fast, and this is having a huge impact on global emissions,” said Seto, a professor of urbanization and geography at F&ES. “But this paper illustrates that there is a window of opportunity to affect how these cities develop and save emissions.
 
“A key take home message is that different types of cities need different mitigation policies to maximize their impact,” she said. “For example, in rapidly growing cities like Changsha, China and Dar es Salaam, Tanzania, the infrastructure is still nascent and many opportunities exist to shape urban form.”
 
But opportunities for mitigation also exist in mature or established cities, she said. In the U.S., for example, researchers found that higher fuel prices would enable more compact development in cities like Boulder, Colo. And in Hamburg, Germany, they suggest that energy savings can be achieved by connecting low-density development to city centers through public transportation and bike paths.
 
“This paper marks important progress as we now gained insights on what mitigation measures are best for different kinds of cities,” said Creutzig, the lead author. “The mitigation potential is greatest in rapidly growing cities and in cities where infrastructure is not set in place and those with low gasoline prices.”
Our study expands the IPCC results by identifying drivers of urban energy use and thus enables effective climate change mitigation strategies across cities worldwide.
— Karen Seto
For their article, “A Global Typology of Urban Energy Use and Potentials for an Urbanization Mitigation Wedge,” the scientists used data sets from the World Bank and the Global Energy Assessment and modeled the development of cities worldwide, representing all city sizes and regions worldwide.
 
The method they used enabled researchers to not only acknowledge the differences between cities but also to bring the urban contribution to saving energy and reducing greenhouse gas emissions together on a global scale, said Giovanni Baiocchi from the University of Maryland.
 
“In China, urban areas are responsible for more than 80 percent of the country’s CO2 emissions because of the high energy demand of these cities combined with China's dependence on coal,” he said. “It is important that China continues to target inefficiencies and invest in energy conservation for example through stricter building codes.”
 
Their analysis builds on the findings published in the 2014 IPCC report, which for the first time included a chapter on the role of cities in mitigating climate change (“Human Settlements, Infrastructure, and Spatial Planning”). Seto was one of two coordinating lead authors on that chapter.
 
“Our study expands the IPCC results by identifying drivers of urban energy use and thus enables effective climate change mitigation strategies across cities worldwide, closing a missing gap of the recent IPCC report” she said.

The original paper:

Creutzig, Felix; Baiocchi, Giovanni; Bierkandt, Robert; Pichler, Peter-Paul; and Seto, Karen. 2014. A Global Typology of Urban Energy Use and Potentials for an Urbanization Mitigation Wedge. Proceedings of the National Academy of Sciences. 10.1073/pnas.1315545112

– Kevin Dennehy    kevin.dennehy@yale.edu    203 436-4842
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PUBLISHED: January 12, 2015
 

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