Despite Germany’s status as the ‘green leader’ of Europe, the capital scored a rather disappointing score of 3.34 out of 10 for environmental protection [1]. Since then, the city has displayed attempts to address climate change and environmental protection against flooding by integrating them within their ‘smart’ approaches. By looking at the newly implemented ‘sponge city’ concept, one can successfully incorporate political and economic forces into the study of environmental change and its management.

The concept

The process of urbanization has increasingly concretized Berlin, and has resulted in an unnaturally high risk of surface water flooding. This risk is heightened by the heavy rainfall experienced in Central Europe, which is expected to worsen as the acceleration of global warming occurs. What is the cities response to these issues you may ask? Well, by permitting the absorption of precipitation to occur, the ‘unnatural’ city begins to behave like a natural environment, and starts to replicate an artificial version of the water cycle [2]. The capital began to introduce the use of green roofs on predominantly larger buildings to begin with, either by development or retrofitting [3]. By planting mosses or grasses on buildings, an evaporative effect can occur which promotes the cooling of the city, and acts as a natural air conditioner. The counterparts of the approach are shown in Figure 1, and the short video clip below will explain more about the process if you’re interested in learning more about the science of it.

The currency of Carbon and circular metabolism

The use of this strategy results in a general reduction of carbon emissions, where three carbon sinks could be achieved in the long term. These derive from runoff pollutant removal, rainwater utilization and carbon sequestration in the green surfaces [4]. These changes signify a metabolic transformation of nature, and the idea of carbon as the currency of urban metabolism provides a useful metaphoric lens when looking at approaches like the sponge city concept [5]. Both in its physical form and its socioecological consequences, carbon has become intertwined with both human and ecological processes. Berlin’s approach aims to correct the linear metabolism identified in most cities, which theorize how resources that enter the city typically leave the city as solid, liquid or airborne waste [6]. In the case of precipitation, it becomes wastewater due to contamination with the concrete, ground and air. By introducing an approach that is resource efficient, climate friendly, resilient and equitable, it can successfully harness these waste products as resources and hence result in a circular and hybridized metabolism. Through this method, the harvesting of roof-runoff is utilized for toilet flushing and irrigation of green areas, while excess precipitation collected is used to fill artificial lakes [7]. The water from these lakes is even cleansed naturally thanks to the planting of Phragmites and use of cleaning biotopes, which facilitates this circular notion of metabolism [7]. This is one of the several examples I aim to explore in this series of blogs where humans are working with nature rather than against it.

Can the ‘sponge’ city ‘suck it up’?

In summer 2017, the highest precipitation levels in the century were experienced which urged the wider implementation of the strategy [8]. One of the key determinants of the strategies’ success is political will, which in this case, is not merely achieved by government but rather governance [9]. This shift was facilitated by the institutionalization under public law of Berlin’s main water management and supplier ‘BWB’ which enabled public private cooperation [10]. Ecological modernization has required the involvement of privately employed urban hydrologists and research engineers, and it is the liberalization discourse in 1990’s Germany which permitted their involvement. The BWB’s research endeavors and their close relationship with the Senate enables political pressure to be applied, and in response to the floods in 2017, a legal requirement for new large developments to manage wastewater was employed [11]. However, to better address issues of global warming and flooding, Berlin need to prioritize public awareness in order for such approach to be deemed ‘equitable’.

Overall, smart approaches specifically aiming to promote sustainability are beginning to interrogate the common perceptions of cities being the opposite of nature, ecology and environment. They underline the pertinence of hybridity, which prompts a fresh debate around the meaning behind the terms ‘natural’ and ‘unnatural’ [12]. In order to uphold environmental justice, public awareness is crucial in encouraging individual households to follow suit and play their part in the collective construction of this ‘sponge’.

Here are the references I used:

[1] – https://www.thelocal.de/20171114/these-are-germanys-10-smartest-cities

[2] – http://44mpa.pl/wp-content/uploads/2017/02/afok_summary.pdf

[3] – https://www.dw.com/en/sponge-city-berlin-plans-for-a-hotter-climate/a-19420517

[4] – https://www.mdpi.com/2071-1050/10/11/3978

[5] – Keil, R. (2003). “Urban Political Ecology.” Urban Geography 24(8): 723-738.

[6] – Gandy, M. (2004). “Rethinking urban metabolism: water, space and the modern city.” City 8(3): 363-379.

[7] – http://www.abcmac.org.br/files/simposio/3simp_rainwaterharvestingingermany.pdf

[8] – https://www.thelocal.de/20170630/weather-calms-but-more-heavy-rain-expected

[9] – Gibbs, D. and Jonas, A.E. 2000. Governance and regulation in local environmental policy: the utility of a regime approach. Geoforum, 31(3), pp.299-313.

[10] – https://de.wikipedia.org/wiki/Berliner_Wasserbetriebe

[11] – https://www.bloomberg.com/news/articles/2017-08-18/berlin-is-becoming-a-sponge-city

[12] – Zimmer, A. (2010). “Urban political ecology: Theoretical concepts, challenges, and suggested future directions.” Erdkunde: 343-354.