Seite - 21 - in options, Band winter 2016/2017

winter 2016/2017 + optionswww.iiasa.ac.at 21 I n 1800, only 3% of the world’s population lived in cities. Today that number is 50%. And by 2050, the UN projects that two thirds of people—over 6 billion people—could live in cities. This growing urban population will make the problems that cities already face—such as poverty, inequality, air pollution, energy, and waste—even more difficult and urgent to address. At the same time, growing urbanization brings opportunities for individuals and society. In recent years, IIASA researchers have contributed to several important studies of urbanization, including a major report on sustainable urban energy systems and an entire chapter of the Global Energy Assessment which focused on the topic. Today, more and more researchers at the institute are turning their attention to the topic, from a variety of angles. When you ask them why, they  agree that cities increasingly drive the future of the planet. AN URBAN PERSPECTIVE One of the major issues facing growing cities, particularly in Asia, is  severe air pollution, which has major impacts on human  health. The World Health Organization estimates that worldwide, air  pollution contributes to nearly 7% of all deaths each year. IIASA researcher Zbigniew Klimont recently returned from Hanoi, Vietnam, where he was working with local policymakers and experts to find solutions to the city’s air pollution problems, using  a  city‑specific version of the IIASA Greenhouse Gas and Air Pollution Interactions and Synergies (GAINS) model. The  GAINS‑CITY model was first introduced several years ago, and has recently been used by a World Bank project focused on pollution in megacities including Hanoi, Beijing, Delhi, and Lagos. “Each city has a different mix of issues and sources of air pollution. The key is identifying the sources of pollution. For example, within  the larger Hanoi metropolitan area, you have large‑scale industries such as steel and cement and the city is also surrounded by villages that have become increasingly industrial. In one they produce furniture, in another, recycle copper. These activities produce a lot of air pollution, which of course does not stay where  it  is produced,” says Klimont. In other cities, poverty is a major cause of air pollution, as people without access to electricity burn solid fuels for cooking and kerosene for lighting. “We need a view of cities that includes the local, regional, and continental sources of pollution as well as considering a local  and  regional portfolio of solutions,” explains Klimont. ADAPTING TO AND MITIGATING CLIMATE CHANGE Cities are also among the most vulnerable places when it comes to climate change and environmental issues. IIASA researcher Mia  Landauer says, “In part, cities are vulnerable simply because so  many people live in them. The more people in one place, the  greater the potential for disaster. But cities are also vulnerable because of geographic reasons: for example, many are located along coastlines, putting them at risk from rising sea level and storms.” Landauer has worked on urban issues at IIASA and previously at Aalto University in Finland, and is a coauthor on the upcoming Second Assessment Report of the Urban Climate Change Research Network. She points out that solutions that take a multi‑issue view, such as “urban greening,” can bring benefits on multiple fronts, saving money, improving air quality and reducing greenhouse gas emissions, while reducing vulnerability to climate change. THE CITY AS A SYSTEM In many ways, a city is like a life form. It consumes—taking in food and energy. It drinks—drawing water from the landscape. And it makes waste in the form of air pollution, garbage, and sewage. This view of a city as an “urban metabolism” dates to the 1960s, explains IIASA researcher Brian Fath. “But there’s been growing interest in recent years because of the growing importance of cities in the global landscape. I don’t think anyone today can argue that cities are  sustainable.” Fath, a researcher in the IIASA Advanced Systems Analysis program and a professor at Towson University in the USA, has  recently been working on models that draw parallels between ecosystems and urban systems. He argues that the more cities could function like natural systems, the  more sustainable they could become. A forest, for example, produces its own energy from sunlight, and waste products become fertilizers for new growth. In contrast, cities import their energy and dump their waste outside their borders. THE TRANSFORMATIVE POWER OF CITIES In a new report for the German Advisory Council on Global Change, to which IIASA researchers contributed, one of the key recommendations was that “cities should assume responsibility for their own transformation pathways.” The report also highlighted the importance of human wellbeing and equality in achieving urban sustainability and climate goals. “The report aimed to develop an understanding of 21st century urban settlement dynamics while reducing complexity to a level that can be analyzed and developed into a strategy. To do this we introduced a three‑level analysis which includes the forces, forms, and values of the overall system,” says IIASA researcher Sebastian  Busch. As cities grow, they also have more power than ever before on the global stage, and they are beginning to take action on issues where national governments and international agreements have yet to find much success. For example, a  new  group of major cities has recently been formed to address climate change on a city level. All cities are different, and solutions that may work for one city may not work for another. Landauer says, “Cities are each complex systems in their own right. They each have different attributes, but there are many common features, and they can learn from each other on how to address these issues.” KL Further info § Grafakos  S, Pacteau  C, Delgado  M, Landauer  M, Lucon  O, Driscoll  P (2016). Integrating mitigation and adaptation: Opportunities and challenges. In: Climate Change and Cities: Second Assessment Report of the Urban Climate Change Research Network (ARC3.2), C  Rosenzweig, W  Solecki, P  Romero‑Lankao, et al. (eds). Cambridge University Press [pure.iiasa.ac.at/13889]. § Liu  F, Klimont  Z, Zhang  Q, Cofala  J, Zhao  L (2013). Integrating mitigation of air  pollutants and greenhouse gases in Chinese cities: Development of GAINS‑City model for Beijing. Journal of Cleaner Production 58:25–33 [pure.iiasa.ac.at/10373]. § Zhang  Y, Lu  H, Fath  BD, Zheng  H (2016). Modelling urban nitrogen metabolic processes based on ecological network analysis: A case of study in Beijing, China. Ecological Modelling 337:29–38 [pure.iiasa.ac.at/13312]. § WBGU (2016). Humanity on the Move: Unlocking the Transformative Power  of Cities. WBGU, Berlin [pure.iiasa.ac.at/12906]. Sebastian Busch busch@iiasa.ac.at § Brian Fath fath@iiasa.ac.at § Zbigniew  Klimont klimont@iiasa.ac.at § Mia Landauer landauem@iiasa.ac.at