Cities are home to 57% of the world’s population, whilst being responsible for the production of 70% of the world’s carbon emissions. This outsized influence places cities as being crucial to the fight against climate change, with UN General Secretary António Guterres stating in 2019 that “cities are where the climate battle will largely be won or lost”. To this end, cities across the globe are initiating a range of actions and projects to reduce their carbon emission impacts.
One such approach is to conduct urban regeneration, described by UN Habitat as the ‘bringing back of underutilized assets and the redistribution of opportunities, increasing urban prosperity and quality of life’. The prevalence of this approach is well illustrated within the EU’s UP2030 project, where 10 of the 11 partner cities are conducting some form of regeneration which expands beyond single building renovations.
Whilst the premise of urban regeneration represents it as an inherently positive action, there are significant issues which blight it, particularly the significant likelihood of resident displacement and gentrification. Therefore, if a city authority is to pursue the path of urban regeneration, it is essential that it is effective; not only in terms of delivering the aesthetic and communal elements which underpin it, but also in terms of carbon emission reduction. For this to be the case, the use of emission data is an essential prerequisite.
Urban Carbon Emission Data
Whilst the majority of the worlds cities have some form of emission data, the scope, quality and applicability of this varies significantly from city to city. Within urban carbon accounting there are two key elements which influence the data available to the city – which calculation method is utilised and which ‘scope’ to account for.
The former relates to whether the city follows a ‘bottom-up’ or ‘top-down’ approach. A bottom-up approach is to calculate carbon emissions through adding an emission factor to activity data, for instance the calculation of a car’s carbon emissions can be calculated by adding an emission factor to the amount of petrol used to power it. On the other hand, a top-down approach takes national level emission data and ‘downscales’ it to the city level. The bottom-up approach, whilst more accurate and granular than the top-down approach, is more difficult and time consuming to conduct.
The other consideration for a city lies in which scope to account for. According to the leading urban carbon emission accounting standard, the GHG Protocol for Cities, there are three different scopes of emissions:
Scope 1: GHG emissions from sources located within the city boundary
Scope 2: GHG emissions occurring as a consequence of the use of grid-supplied electricity, heat, steam and/or cooling within the city boundary
Scope 3: All other GHG emissions that occur outside the city boundary as a result of activities taking place within the city boundary
Whilst accounting for scopes 1 and 2 is the most common form of carbon accounting, the bulk of city emissions (especially those in service economies) comes from the consumption of goods, namely scope 3 – with many cities having over 80% of their emissions based in scope 3. This difference between territorial (scopes 1 and 2) and consumption based accounting (scope 3) is a decision cities have to make when conducting their carbon accounting. However, the ability to conduct the more accurate consumption accounting is contingent on expertise and data availability.
Another element for cities to consider is which elements of the city are being accounted for. Through a literature review conducted by the author (in development), concerning the use of urban carbon emission data within cities, distinct domains of urban carbon emission accounting have been observed:
Organisational – Basic Accounting
In terms of a city authority conducting urban carbon accounting, monitoring their own emissions is the least complex. This is primarily owing to the availability of data, be it national level data which can be downscaled or activity data which can be applied to emission factors to work out the bottom-up emissions of a city authority.
City-wide – Standard Accounting
This form of accounting covers the emissions of the whole city, rather than solely the authority. Here, both top-down and bottom-up approaches can also be used. Whilst scopes 1 and 2 are most commonly accounted for, some cities (particularly in Finland and Sweden) are pioneering different approaches to adequately account for citizen consumption emissions.
Project – Advanced Accounting
Whilst there are examples within academic literature demonstrating the potential value for project level accounting within cities, the implementation of such an approach is a complex and time consuming one. To this end, the majority of city authorities lack the capacity to assess the emissions arising from specific projects.
Policy – Highly Advanced Accounting
Owing to the challenges of determining which elements of the city are to be factored into analysis, the accounting of policy decision carbon impacts is the most complex approach to pursue, and to this end, has not yet been applied to the urban realm. However, the GHG Protocol: Policy and Action Standard does demonstrate a methodological route for cities to pursue if they wish to conduct such accounting.
Whilst the above four domains of urban carbon accounting represent the spectrum of approaches, from the common through to the as of yet undeveloped, each one is essential for a city to adequately understand its emission impacts. This is particularly true when cities, such as those within UP2030, are cultivating carbon neutrality through urban regeneration strategies.
Emission Data and Urban Regeneration
Such project based approaches, whilst potentially beneficial along sociological, environmental and cultural lines, are at best inefficient regarding the reduction of carbon emissions. This is owing to a lack of project level emission data and the unsuitability of city-wide or organisational data. To this end, cities who pursue emission reductions through urban regeneration, without the adequate emission data, do so by acting upon good faith that their actions are inherently carbon positive. This is a risk, given that whilst many approaches appear to be inherently carbon positive, the emissions produced through their development, installation, maintenance, removal and disposal may outstrip those avoided in their functioning.
Therefore, the barrier of inadequate data collection, access and use is a crucial one to overcome for urban regeneration projects to be a more effective approach for reducing carbon emissions. To this end, myself and Dr Kristen MacAskill at the University of Cambridge’s Centre of Sustainable Development are developing, within the UP2030 project, a methodology for city authorities to account for their urban regeneration carbon emission impacts. This is initially centred around building retrofits, active travel and urban greening – the three most common approaches to reducing emissions through urban renewal – with the accounting of regeneration consumption emissions being a future research priority.
With a lack of adequate emission data, the current promises of emission reductions though urban regeneration is at best an inexact science and at worst contributing to the already significant carbon footprint of the world’s cities. Therefore, the barrier of ill suited emission data is one which needs transcending, amongst many others discussed at the Barriers and Enablers for Urban Climate Governance workshop hosted by the International University of Catalonia.
Dr Will Brown
Research Associate in Urban Systems and Carbon Management, Centre for Sustainable Development
University of Cambridge