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The Environmental Footprints of Eight Metropolises

The Urban Footprints project studies how different cities contribute to conserving the climate and resources – and what they can do to improve

Freiburg, Dec 08, 2020

How can cities contribute to conserving the climate and resources? Dr. Cathrin Zengerling, assistant professor in Transformation to Sustainable Energy Systems at the Institute of Environmental Social Sciences is investigating this question. Amongst other things, she is researching the mechanisms with which large cities manage their greenhouse gas emissions and how CO2-intense resources can optimally be used in cities. In honor of the 50th anniversary of the Faculty of Environment and Natural Resources (UNR) we are publishing a series of articles on its departments and research projects. Part 7 – City – shows how the Urban Footprints project is studying climate protection in different metropolitan areas.

As a city state, Hamburg has passed legislation strengthening and amplifying its climate protection plan. Photo: Powell83/ 

“High energy consumption and greenhouse gas emissions make cities a major player in conserving the climate and resources, one whose significance will grow with increasing urbanization,” says Cathrin Zengerling, a legal specialist in environmental, energy, planning and international law. Despite their implicit responsibility cities are not generally subject to any legal duties to achieve specific climate protection targets, she adds, “As sub-state bodies they aren’t for example bound by the two-degree target of the 2015 Paris Agreement.” With her Urban Footprints project Zengerling wants to find out from eight metropolises whether and how, aside from legally-binding agreements, climate and resource conservation can be managed in cities. One aim is to develop recommendations based on the results, to help cities make the most of their potential to conserve the climate and resources. A Volkswagen Foundation ‘Freigeist’ fellowship is funding the project and the Urban Footprints research group. Zengerling launched the project at HafenCity University of Hamburg in 2018, moving to Freiburg in 2019.

From Hamburg via Cairo to São Paulo

For answers to her research questions, she is drawing on data from the metropolitan areas of Cairo (Egypt), Shenzhen (China), Lagos (Nigeria), Toronto (Canada), New Delhi (India), São Paulo (Brazil), New York (USA) and Hamburg. In the first stage, Cathrin Zengerling and her colleagues Lisa Harseim and Nikita John are studying what tools and processes the cities use to manage their internal climate protection planning and how this helps them to fulfill their responsibilities and accountability. The group is also investigating the accountability chains by which the cities are integrated in the various pillars of the climate protection regime. To do this, the scientists analyze climate protection plans and monitoring reports and compile their findings in a database that consists of four columns. According to Zengerling, initial results reveal a variety of approaches to management that have made it more difficult to quantify and compare urban contributions to climate protection.

“The metropolises have committed more or less bindingly to climate protection. In early 2020 Hamburg passed a climate protection act; other metropolitan areas have simply written non-binding climate plans,” she says, summing up two examples from the ‘Responsibility’ column. The question of how openly and transparently they communicate their activities and their effects (‘Transparency’ column) also yields differing results: “While Hamburg presents its climate balance on the Internet and New Delhi recently imposed a transparency initiative for planning processes, we find hardly any public information for Lagos and Cairo.”

The legal specialist explains that depending on the form of the state, metropolitan areas had different amounts of freedom to protect the climate and to involve others in developing, implementing and monitoring their plans (‘Responsibility’ and ‘Participation’ columns). “In its special role of a city state in our federal system, Hamburg was able to complement and strengthen the climate protection plan with an extensively revised local climate protection act. The German constitution grants extensive scope for action at a communal level. In centralized states local governments have far less influence. As a special economic zone, the Chinese city of Shenzhen is an exception here.”

A Better Combination

As well as revealing differences, the analysis also highlights potential for optimization – for example in the ‘Evaluation’ column. This illustrates how the cities in the project measure and evaluate their greenhouse gas emissions and their development. “Usually they only calculate emissions that are produced within the city boundaries or its immediate vicinity. For instance from generating electricity and heat, from buildings or mobility,” explains Zengerling. She criticizes this for not taking into account the real greenhouse gas emissions that are caused by urban infrastructures and lifestyles, and that consumption-related emissions are not also taken into account alongside the production-related ones.

Zengerling believes that to obtain a telling result, upstream or indirect emissions should also be included in climate balance sheets, that is, those that are produced regionally or globally in the production and transport of goods consumed in the city. “Various research projects are currently developing methods to calculate urban consumption-based greenhouse gas emissions so as to incorporate them in climate protection plans. New York for instance is planning to extend its data appropriately,” says Zengerling, who advocates a single methodical standard for urban greenhouse gas balance sheets.

Focus on Conserving Resources

In the next stage of the project, the scientists will study whether there is already management of resource conservation in the metropolises and whether climate protection plans are suitable as a model for this. To this end, the team will be studying how cement, steel and phosphorus are used in the cities, and whether they can be recovered and reused. “Although the production of building materials is very CO2-intensive, the resource is often lost as rubble and ends up at the dump instead of being recycled,” explains Zengerling. An alternative comes from the city and canton of Zurich. There, thanks to guidelines on the use of recycled concrete in the city’s own buildings as well as other measures they have managed to achieve a recycling rate of more than 80 percent of mineral building waste as building materials in the Canton of Zurich. “This clearly shows how cities can live climate and resource conservation,” says Cathrin Zengerling. “We want to study whether a similar strategic plan would also be worthwhile and feasible in the metropolises in our project.”

Kristin Schwarz


More articles from this series:

Volcano in the Lab

Humans and Hedgehogs

Eddy-fying Research

Water shortages lead to heightened conflicts

It’s the mix that counts

A Green Economy Based on Wood?