How cities can prepare for the future

"The extreme weather conditions are highly stressful for humans and the natural world. To limit their impact, we are working on a new, green, future-ready urban concept," says Prof. Werner Lang, head of the Centre for Urban Ecology and Climate Adaptation at the Technical University of Munich (TUM).

"It's not only about climate protection strategies," says Lang. "We also want to develop sustainable living concepts for major population centres."

Bavaria's State Minister of the Environment and Consumer Protection Ulrike Scharf emphasises: "Climate change is progressing worldwide, and Bavaria is no exception. This is why we have to act now. This research project will provide municipalities with examples of how it is possible to adapt to climate change in the city and protect nature at the same time."

To make cities future-ready, researchers from the fields of architecture, urban planning, and landscape architecture and design are cooperating closely with experts in ecology, biology and sociology.

"The interdisciplinary approach is important because any measures taken to adapt cities to climate change will impact the interplay of the human, animal and plant worlds," says Lang, who heads the Institute of Energy Efficient and Sustainable Design and Building at TUM.

The complexity of these interactions is illustrated by the study of three model settlements conducted under the subproject "Climate protection and green infrastructure in the city". The researchers compared three residential areas:

Munich's Maxvorstadt district, where buildings are grouped around inner courtyards, the Neuaubing settlement outside Munich, with its spaced low-rise buildings, and Würzburg, which has a medieval town layout.

In all three, the researchers measured the energy needs of the buildings and simulated the microclimate impact of roof, façade and open space vegetation. At the same time they investigated the animal and plant species that can be integrated into the three settlement types and their positive effects on biodiversity.

At the Symposium for Climate Research, Urban Ecology and Climate Adaption, the TUM team and their cooperation partners presented their results to the University of Würzburg, the University of Kassel and the Bavarian State Office for Viticulture and Horticulture.

"The biggest challenge for sustainable urban development is taking the differing interests of humans and nature into account, but also giving due consideration to climate protection priorities," says Prof. Stephan Pauleit, the head of the Chair for Strategic Landscape Planning and Management and the deputy head of the Centre for Urban Ecology and Climate Adaptation.

For example, as increasing numbers of people move to urban centres, they need housing. Open spaces are filled in. But this densification, as the process is known, results in the loss of green space.

The consequences: Water runoff is prevented, plants lose habitat, and there are fewer trees to provide shade, generate oxygen and cool the surrounding air through the evaporation of water on leaf surfaces.

Many animal species also lose their habitat and the microclimate deteriorates. The warming resulting from climate change amplifies these effects. This can lead to intolerable heat in the summer.

Those who understand these interrelationships can take corrective action now: by using regenerative energy sources wherever possible, planning for traffic calming areas and green spaces, planting trees, and constructing buildings with vegetation on roofs and facades.

The greening of the city not only improves the air quality, but also reduces the energy needs of buildings because the need for active cooling in the summer is eliminated or at least reduced. Not all autochthonal plants are suitable for life in the city, however: In Bavaria the lengthy heat waves and droughts caused by climate change are already impacting deciduous trees.

In the subproject "City Trees II", a group of researchers are studying whether the plane trees frequently used in the Mediterranean region, but also in these parts, or the black locust from North America, are better able to withstand climate stresses than the native small-leaved lime tree. They are also looking at the possible effects of future climate conditions on the growth and performance of the species under investigation.

The results can benefit municipalities and building departments. The researchers are planning to publish guidelines in July as an aid to future climate-adapted urban planning. The work is being supported by the Bavarian State Ministry of the Environment and Consumer Protection.