The recent visit of 65 mayors to the Vatican to discuss climate change, among other things, reflects the central role of cities in debates that for too long only took place at the global and national level. By necessity and by their nature, cities are having more success than national or international governments in addressing climate change.

Cities house more than half the world’s population, consume 75 per cent of its energy and emit 80 per cent of all greenhouse gasses. But they are not just sources of problems; they are innovative sites for policy solutions.

Indeed, while the story of climate change is often depicted as a depressing repetition of huge problems with time running out, the story of cities and climate change is more optimistic.

The high concentration of populations and investment puts cities at the very heart of climate change issues. In drier regions, such as the south western United States, summer heat waves and droughts can cause health problems and strain water supplies for agriculture. In regions such as the northeast, cities are experiencing wetter winters with heavier snowfall.

Many of the world’s cities are close to the sea, and many of the most vulnerable ones are those in coastal locations. Cities in the developing world, in particular, are often more vulnerable to natural disasters but less able to spend billions of dollars to upgrade their infrastructure to better withstand flooding or similar measures.

Cities such as Dhaka, Mumbai, Bangkok, Manila and Ho Chi Minh City are already in low-lying areas that now have the threat of increased flooding from extreme weather. The city of Jakarta in Indonesia is challenged by flooding that accompanies the yearly monsoons. But land subsidence from compaction from new skyscrapers, and increased groundwater extraction for a growing population, has meant that the city is sinking 10 times faster than the Java Sea is rising because of climate change.

There is an unevenness to those most at risk; the urban poor, infants and elderly are most vulnerable.

The nation state can be both too big to deal with urban issues and too small to affect global affairs

The brute facts of climate change vulnerability in cities are prompting a new and more pronounced urban environmental sensitivity, and cities are responding through both mitigation and adaption.

Mitigation focuses on reducing the concentrations of greenhouse gases – using alternative energy sources, encouraging greater energy efficiency and conservation – and through the promotion of carbon sinks by planting trees.

Curitiba in Brazil is the showcase for many successful policies, including the integration of green spaces within the city, a widely used public transportation system and reduction of waste.

Curitiba, Brazil has implemented what is considered a very functional rapid transit system that reduces emissions and makes the city more livable. Image: Morio, CC BY.

Separately, cities are adapting to the effects of climate change. Chicago has developed policies anticipating a hotter and wetter climate by repaving its roads with permeable materials, planting more trees and offering tax incentive to encourage green office roofs.

Why are cities promoting this shift? There is a bottom-up movement from residents pushing for a better quality of urban life. Global climate change issues such as the shrinking ice sheets and the perilous state of polar bears are real, yet these problems are distant, long-term and difficult for urban residents to solve.

But these residents have an immediate experience of poor air quality in their city and a greater ability to leverage local polices to effect change. Global issues that seem distant yet pressing create a sense of anxiety without a clear route to immediate political response: solutions struck in international negotiations can take decades.

Indeed, the nation state can be both too big to deal with urban issues and too small to affect global affairs. National legislatures, such as the US Congress, whose debates are shaped more by big monied interests than the everyday needs of local citizens, can too often get locked in ideological disputes and policy paralysis.

By contrast, the city – and its government – is small enough to connect with citizens and tailor specific polices, while large enough to make a real difference. For that reason, cities are the ideal stage for developing policies and practices of sustainability compared with global and the national bodies.

There is also growing competition among cities. As the world globalises, cities are assessed by international standards in the competition for investment, skilled people and creative industries. Cities need to respond to the demands of an increasingly mobile and ecologically aware capital and global talent pool. Cities are now ranked, compared and assessed by the greenness of their environment and their success in moving toward more sustainable policies.

Urban networks

Cities are nodes in a global network of flows of people, ideas and practices. While the world is often described as a map of separate national states, it can be also visualized as a global urban network. Cities are learning from each other and testing policies, with the more successful ones diffused, adopted and adapted around the global network.

By 2014, the US Conference of Mayors Climate Change Agreement included 1,054 mayors representing a total population of more than 88m citizens.

Through local government, city residents can actually address poor air quality, all while reducing greenhouse gas emissions. Image: Steven Buss/flickr, CC BY-SA.

The organisation helps cities with policy formulation to accelerate energy efficiency and adapt infrastructure to meet international standards by discouraging sprawl and encouraging urban greening. Many US cities have initiated environmental legislation that exceeds US Environmental Protection Agency standards and even, in the absence of national leadership, meets international standards.

Meanwhile, the C40 Cities Climate Leadership Group is a group of the world’s largest cities committed to tackling climate change to reduce carbon emissions and to increase energy efficiency. Forty cities signed up in 2006, hence the name; but more than 75 cities are now committed to the project. Their combined population is over half a billion.

We have much to learn from people and communities at the margins of world cities. In the past 60 years, between one and two billion people have created self-built communities in cities all over the world.

They have quite literally made their urban environments. This is not to romanticize the problems in slums. But our present environmental predicament is in large part due to an unthinking reliance on technology, and the assumption that the higher-tech the better. The slums of the world provide an invaluable lesson in creating cities with limited resources. They are in fact a living experiment in doing more with less. There are many lessons we can learn for this 60-year experiment of informal urban living.

There is a lot of bad news concerning climate change as our planet gets hotter and more vulnerable to environmental risks. But the cities of the world are where adaption and mitigation policies are being tried and tested. They are also a source of new jobs as the urban green economy generates new alternatives to traditional occupations.

The cities are the cause of many of our environmental problems– but also, as it turns out, the solution.

John Rennie Short is a professor in the School of Public Policy at University of Maryland, Baltimore County.

This article was originally published on The Conversation. Read the original article.