A new study suggests that urban planning and transport policies can limit the future increase in cities' energy use by about one-forth, from 730 EJ to 540 EJ in 2050, according to a study in the Proceedings of the National Academy of Sciences. If current urbanization trends continue, urban energy use will more than triple by 2050.
Cities in developing countries in Asia, Africa and the Middle East have the highest potential of energy savings by urbanization - 86 persent of the world's total potential. In order to achieve these savings urban planning should be oriented towards short commutes between home and work places through public transportation combined with land use mix.
Researchers at the Mercator Research Institute on Global Commons and Climate Change (MCC) together with colleagues from Yale University, the University of Maryland and the Potsdam Institute for Climate Impact Research also identified mitigation opitions in mature to established cities. "Through this study we provide critical new insights into how different types of cities can most effectively mitigate the effects of climate change", says Felix Creutzig, lead author of the study and head of the working group Land Use, Infrastructures and Transport at the MCC. A key take home message is that the eight different types of cities found in the study each need different mitigation policies to maximize their impact.
In regards to policy options Creutzig points out: "The mitigation potential is greatest in rapidly growing cities and in cities where infrastructure is not set in place. This way lock-in on high carbon emission pattern can be avoided."
Changsha in China and Dar es Salaam in Tanzania are both rapidly growing cities where infrastructure is still nascent, and many opportunities exist to shape urban form. The researchers also identified potential mitigation strategies in mature or established cities. In the U.S., for example, higher fuel prices would enable more compact development in cities like Boulder, Colorado. And in Hamburg, Germany, energy savings can be achieved by connectiong low-density development to city centers through public transportation and bike paths.
Policies on a national level are also very important. "In countries like Iran or the USA a rise of fuel prices would incentivize a transition towards energy efficient cities", says Creutzig.
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 274 cities, representing all city sizes and regions worldwide.
Only recently the IPCC has highlighted the role of cities in mitigating climate change showing that urban areas consume up to 76 percent of the global energy and generate about three quarters of global carbon emissions. More than half of the world's population lives in cities by now and the share is rapidly increasing. "Our study expands the recent 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," says Karen Seto a professor of urbanization and geography at Yale University, who leads the IPCC's urban mitigation chapter and is co-author of this study.
"We know that the growth of cities in Asia, Africa and the Middle East is enormous and is happing fast, and this is having huge impact on global emissions," said Seto. "But this paper illustrates that there is a window of opportunity to affect how these cities develope and save emissions."
"Our method enabled us not only to 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," says Giovanni Baiocchi associate professor in the Department of Geographical Sciences at 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," Baiocchi points out. "It is important thate China continues to target inefficiencies and invests in energy conservation for example through stricter building codes."
References of the cited articles:
Creutzig, Felix; Baiocchi, Giovanni; Bierkandt, Robert; Pichler, Peter-Paul; Seto, Karen (2015): A Global Typology of Urban Engergy Use and Potentials for an Urbanization Mitigation Wedge, Proceedings of the National Academy of Sciences, doi: 10.1073/pnas.1315545112
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