Climate-sensing with Trees: How Sensing Comes to Matter in Central Germany

By Catharina Lüder

If climate change is not only seen as an environmental problem but as a state of the world, then the question is not 'how to manage it' but 'how to sense it'. Referring to Candis Callison (2014), it is important to look at “how climate change comes to matter.” In this piece I argue that it comes to matter through climate-sensing (Hepach & Lüder 2023).

When I interviewed council workers and urban planners on their everyday encounters with climate change, scientific evidence was one dominant lead for them to find locally feasible options for dealing with climate change impacts, such as heat in cities. Another point of reference were their own bodily experiences of heat and drought together with visible signs of brown-leaved trees. They sensed climate through a combination of experiences and measurements.

This is in line with a general societal development in Germany. The biennial study “Umweltbewusstsein in Deutschland 2022" (Environmental Awareness Study 2022) shows that concern for personal health due to climate change rose by 14 % compared to the results from 2016 (2016: 59 %; 2022: 73 %). This means that the German public is becoming more aware of the everyday importance of climate change not only through scientific measurements of rising annual mean temperatures (IPCC 2021) but to a large extent through personal experience. By the time I was conducting fieldwork on everyday effects of climate change in Germany, many people changed their mind about the question of whether climate change is affecting their lives on an everyday basis or not, because they could see, feel and learn about it in their everyday lives.

After I went to the field in the city of Kassel (Hesse, Central Germany) in late 2017, things took off quickly: In 2018 the Fridays for Future movement was all over the media and in the same year a heatwave combined with a severe drought hit Germany (Rousi et al. 2023). Suddenly, people could see what climate change was doing in their surroundings because dead trees in the city were turning their leaves brown in the middle of summer. Talks about heat exhaution could be heard regularly at bus stops, in the streets, and in many interview meetings. Seeing and feeling climate change was complemented by local Fridays for Future demonstrations followed by an increase in media coverage on the scientific evidence of climate change impacts. This combination changed how climate change mattered in the city of Kassel.

As Callison writes, it is important that climate change is understood as a multi-faceted phenomenon and calls for integrated ways of dealing with it (Callison 2014: 244). That means to consult multiple perspectives of the relevant actors, including citizens, planners, council workers as well as multispecies urban dwellers like trees. Urban planners promote the integration of more greenery in cities, acknowledging trees as vital co-inhabitants. They do this by relying on quantitative measurements such as the cooling effect of green spaces in urban areas (Quaranta et al. 2021, with a particular emphasis on trees Schwaab et al. 2021), but they also refer to their own climate-sensing. One interviewee summed it up:

"I just think about what it's doing to me. Today is one of those days when you can really feel the effects of climate change. Today I find it totally exhausting because of the weather. And it [meaning climate change] is here now, so one way of protection is certainly to have appropriate shading, both in buildings and in public spaces. Trees, for example, in public spaces. A lot more of them need to be planted to provide shade." (Interview with city planner, 26.8.2019, translation by CL)

In Kassel, connections were made between everyday lives and climate change because citizens, council workers and urban planners developed a way of climate-sensing that allowed them to link scientific evidence with their personal, bodily experiences through a combination of a spatio-temporal positioning of bodies together with multiple modes of knowing environmental states by experiencing, measuring and anticipating (Hepach & Lüder 2023). Contrary to theoretical approaches that view climate change as remote from human experience (Jasanoff 2010, Morton 2013, Rudiak-Gould 2013, Chakrabarty 2018), this shows that experiences and measurements are inseparable. Already Goethe described how temperature is sensed by us in accordance with what we see on the thermometer and, in a similar approach, modern weather forecasters complement measurements and model calculations by their everyday weather experience, for example, when driving to work by bike (Hepach & Lüder 2023: 352, 356–359).

Heat stress was one of the most prominent effects of climate change that influenced my fieldwork in Kassel and many trees were displaying visible distress signals with their brown leaves and dead branches. But still, urban green was seen as the most effective adaptation measure for the city to alleviate heat stress from dwellers (Gangwisch et al. 2023; Lüder 2023, pp. 225-294). However, during the summer of 2019, the concerns of my interlocutors did not stop at our human distress caused by the heat. Many conversations began by discussing how desperately trees needed water, and how dead, brown-leaved branches were becoming increasingly visible throughout the city. Trees are not only a solution to climate change issues. In fact, they are under pressure themselves from the climate change induced heat and drought that threaten their health condition. Climate change is apparently a multispecies phenomenon, too.

In order to provide shade and cooling, trees need to be healthy with a dense, green canopy under which human bodies can find relief from overheating climates (Kabisch & van den Bosch 2017). This effect is not subjective, but rather a result of the tree's physical properties (Schwaab et al. 2021), making trees important inhabitants of cities.

Council workers in Kassel were compelled to better care for trees, firstly, because of what they had felt in their daily lives. They made sense of the scientific advice that is included in their professional training (e.g. through networks, professional societies and collaborations with the University of Kassel) to use the effects of plants for urban planning with so-called ‘nature-based solutions‘ (Kabisch et al. 2017) or ‘green infrastructure‘ (Voghera & Giudice 2019) through combining it with their own experiences. Secondly, they see the brown leaves and dried out branches and they know that changing the way city trees are treated is inevitable. This shows how bodily experiences of heat, measurements of temperatures and precipitation and anticipation of ongoing effects like health issues of trees and humans are the three critical elements for climate-sensing in Kassel. Climate-sensing involves both humans and trees.

Climate-sensing can also be seen in a broader perspective as being response-able to one's own and others' environment(s). Thinking with Donna Haraway, this means that species are able to find ways to respond to each other without dissolving their differences (Haraway 2008: 71). I combine Haraway’s concept of being response-able with Jane Bennett’s notion of vibrant matter (Bennett 2010) in order to show what climate-sensing means in a multispecies world. Vibrant matter in Bennett’s understanding is a form of being that exerts effects as part of heterogeneous assemblages (Bennett 2010: 3, 23). A tree, for example, affects who can live in a specific area or designs the pavement with cracks by its bigger roots; it affects how much shade is on the bench under it during the day and how cool the surrounding air gets in the night. It is part of a street assemblage – together with concrete, other plants, buildings, vehicles, humans and other species like birds, squirrels and dogs, to name just a few. Drawing on Haraway’s and Bennett’s thinking, I argue that trees are lively things and respond to the places that humans have designed and constructed for them by their vibrancy or by their prolonged death.

Trees exert effects through their health condition. If they are healthy with a dense, green canopy, they cool down the area around them. In contrast, branches gone dead are potentially dangerous when breaking off due to severe weather. As a result, governance of urban green spaces is compelled to rethink and restructure how trees are managed and cared for. Trees respond to climate change and to urban habitats that leave them with too little water. Green space managers and city planners respond to the trees’ suffering by trying to find new ways of designing urban areas with more green and by urging for more resources (in Kassel, most of all for personnel) to take care of them, such as providing them with proper watering and a more biodiverse habitat.

Local authorities are developing new experiences with the trees they plant, water and care for. By measuring and comparing different characteristics that help trees to cope with urban climates, many city authorities in Germany are compiling a list of tree species that are more resistant to new climatic conditions (available in German here: https://epaper.galk.de/index.html#36). By climate-sensing, they become response-able to the trees’ needs who, in return, affect climate-sensing as vibrant matters. Trees retain their influence in city assemblages as the basic environmental conditions have changed, putting a strain on all species living in urban environments. They enter urban green space governance as active parts of climate assemblages by the climate-sensing of city planners and green space managers. To conclude, that means that in climate changed cities, climate governance and climate-sensing complement each other.

References

Bennett, J. (2010): Vibrant Matter: A Political Ecology of Things. Durham, London: Duke University Press.

Callison, C. (2014): How Climate Change Comes To Matter. The Communal Life of Facts. Durham, London: Duke University Press.

Chakrabarty, D. (2018): Anthropocene time. In: History and Theory 57(1), 5–32.

Gangwisch, M.; Saha, S.; Matzarakis, A. (2023): Spatial neighborhood analysis linking urban morphology and green infrastructure to atmospheric conditions in Karlsruhe, Germany. In: Urban Climate 51, 101624.

Haraway, D. (2008): When Species Meet. Minneapolis: University of Minnesota Press.

Hepach, M.G.; Lüder, C. (2023): Sensing weather and climate: Phenomenological and ethnographic approaches. In: Environment and Planning F 2/3, 350–368.

IPCC -Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.) (2021): Climate Change 2021. The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, UK/New York, USA: Cambridge University Press. Kabisch, N.; Korn, H.; Stadler, J.; Bonn, A. (eds.) (2017): Nature-Based Solutions to Climate Change Adaptation in Urban Areas. Cham: Springer.

Jasanoff, S. (2010): A new climate for society. In: Theory, Culture and Society 27(2), 233–253.

Kabisch, N.; Korn, H.; Stadler, J.; Bonn, A. (eds.) (2017): Nature-Based Solutions to Climate Change Adaptation in Urban Areas. Cham: Springer.

Kabisch, N.; van den Bosch, M. A. (2017): Urban Green Spaces and the Potential for Health Improvement and Environmental Justice in a Changing Climate. In: Kabisch, N.; Korn, H.; Stadler, J.; Bonn, A. (eds.) (2017): Nature-Based Solutions to Climate Change Adaptation in Urban Areas. Cham: Springer, pp. 207-220.

Lüder, C. (2023): Klimawandel im Gefüge städtischer Alltagspraktiken. Bedeutungsvolle Praktiken, unsichere Kompetenzen und sterbendes Stadtgrün als lokale Herausforderungen. Hildesheim, München: Georg Olms Verlag/UB der LMU München.

Morton, T. (2013): Hyperobjects – Philosophy and Ecology after the End of the World. Minneapolis: University of Minnesota Press.

Quaranta, E., Dorati, C.; Pistocchi, A. (2021): Water, energy and climate benefits of urban greening throughout Europe under different climatic scenarios. In: Scientific Reports 11, 12163.

Roudiak-Gould, P. (2013): ‘We have seen it with our own eyes’: Why we disagree about climate change visibility. In: Weather, Climate & Society 5(2), 120–132.

Rousi, E. Fink, A. H.; Andersen, L. S.; Becker, F. N.; Beobide-Arsuaga, G.; Breil, M.; Cozzi, G.; Heinke, J.; Jach, L.; Niermann, D.; Petrovic, D.; Richling, A.; Riebold, J.; Steidl, S.; Suarez- Gutierrez, L.; Tradowsky, J. S.; Coumou, D.; Düsterhus, A.; Ellsäßer, F.; Fragkoulidis, G.; Gliksman, D.; Handorf, D.; Haustein, K.; Kornhuber, K.; Kunstmann, H.; Pinto, J. G.; Warrach- Sagi, K.; Xoplaki, E. (2023): The extremely hot and dry 2018 summer in central and northern Europe from a multi-faceted weather and climate perspective. In: Natural Hazards and Earth System Sciences 23/5, 1699–1718.

Schwaab, J.; Meier, R.; Mussetti, G.; Seneviratne, S.; Bürgi, C.; Edouard, L. D. (2021): The role of urban trees in reducing land surface temperatures in European cities. In: Nature Communications 12, 6763.

Voghera, A.; Giudice, B. (2019): Evaluating and Planning Green Infrastructure: A Strategic Perspective for Sustainability and Resilience. In: Sustainability 11/10, 2726.