The Bartlett


Balancing act

Dr Zhifu Mi, Research Fellow at The Bartlett School of Construction and Project Management, says cities are a trade-off between economic development and climate change mitigation.

High rise buildings from above
 Q. Why are cities so important to the study of climate change mitigation?

Cities are at the core of climate change mitigation. They will soon be home to more than half the world’s population and are also responsible for up to three-quarters of global greenhouse gas emissions. But cities are also the centres of wealth – they have the resources, and a responsibility, to address climate change. What’s more, cities on the coast or on rivers are particularly vulnerable to its impact. It will bring much greater risk to urban settings.

Q. What are the big knowledge gaps?

The first big knowledge gap is data on emissions. Data is the foundation of research and critical to the policy mix for mitigation, and there is a lack of consistent and comparable carbon emission data at a city level. 

Most of the metrics are at a global or national level, while different cities have different methods for compiling carbon emission data, which means that the data cannot be compared. This the most important issue – to develop consistent and comparable emission data. 

Q. How do you get consistent emissions data? 

An increasing number of studies are trying to solve this problem. For example, I’ve been looking at carbon emission data at the city level in China. We have emissions data for more than 150 Chinese cities, all collected using the same metrics, so they can be compared, and researchers can download this data for free.

Q. Are city policy-makers sufficiently informed to make decisions on mitigation?

When cities make climate change policies they need to do cost-benefit analyses: they need to know how climate change will affect them in the future and they need to know the risk and the cost of not taking measures to mitigate climate change. But currently there are large uncertainties about how climate change will affect cities. 

We have a weak understanding of it. Climate change impacts are often examined at a global level, rather than at a local level, and it is much harder to predict the impact at a local level. There is also lack of scientific understanding of the trends inclusive to development and climate change mitigation. Currently, cities would like a high GDP and also a good environment, so there is a trade-off between economic development and climate change mitigation. We need to better understand this balance point, as this will be different for each city.