By Joe Peach and Rashiq Fataar

Money is tight in today’s cities. We’ve lived with challenges of the ‘current economic climate’ for so long now that it should probably be renamed ‘the economic climate’, and, for some cities at least, sustainability seems to come with a price tag beyond their budgets and no guarantee of economic growth.

The infrastructure that keeps our cities going is, more often than not, old and inefficient. Though the transition to more sustainable power for transport is underway, is it happening fast enough? When public transport networks and private vehicles are predominantly powered by fossil fuels, air quality is the first thing to suffer, swiftly followed by the health of a city’s residents. More than 4,000 people die every year in London as a result of its air quality - a human tragedy with significant economic repercussions. The cost of transforming public transport and establishing higher emissions standards would hit us all in the wallet, but what about the social, environmental, and economic benefits this would bring to a city? Surely they would benefit us too?

In the UK alone, 3.3 billion litres of water are lost every single day through leaking pipes. The congestion that holds up many inner city roads has a huge economic cost, but so does the infrastructure required to install a congestion pricing system. And despite countless studies suggesting economic advantages from bicycle networks, developing cycling infrastructure remains a second thought for many cities.

Recently, Cape Town has started to get serious about its economic future, forming an Economic Development Partnership with various local and regional agencies. The aim of this collaboration is to combine evidence led economic decisions with regional strategy that creates inclusive growth in a region with an unemployment rate well over 20%. The extent to which sustainability will play a role in driving this shared vision is yet to be seen. It is entirely reasonable to believe that cities and provinces in developing countries may forego sustainability when pursuing growth rates comparable to other developed and developing countries.

Madrid is considered by many to be a liveable city, with one of the most reliable and extensive transport systems in the world, beautiful public parks and highways buried to ensure open space for citizens. However, the economic impact of pursuing this aggressive strategy (with high levels of debt), while making the city a better place to live, has also placed the entire economy at risk. Though it would be inaccurate to attribute a near economic collapse solely to the infrastructural investments made by the Spanish government, they are a contributor, and an important reminder that economic sustainability is equally important as environmental and social sustainability.

So how do we justify sustainable urban development when cities with stretched budgets are struggling to do more with less? Is sustainability a long term economic investment, or purely a social investment in the current wellbeing of citizens? And if it is economically justifiable to invest in creating sustainable cities, how can we make the potential benefits seem more tangible?

On Thursday, This Big City and Future Cape Town are launching #CityTalk - a monthly tweetchat about cities - and we want you to join us. So if you want to share your views on the economics of sustainable cities, get yourself on Twitter this Thursday, January 19th at 7.00PM London GMT / 9.00PM Cape Town SAST / 2.00PM New York EST. And if you want to know how it all works (or, like me a few months ago, you have no idea what a tweetchat is), read all about it here.