Recent events make it drastically clear: weather outbreaks are becoming more extreme. In July 2021, it was extreme precipitation in North Rhine-Westphalia, Rhineland-Palatinate, Bavaria and Saxony; in 2018 and 2019, Germany suffered from prolonged drought and heat. Recent climate studies show that the likelihood of both extremes will increase. It is time for a large-scale climate adaptation program. Scientists from 11 different institutions, coordinated by the Helmholtz Centre for Environmental Research (UFZ) and with the participation of the German Research Centre for Geosciences (GFZ), have defined five key principles that cities and communities should use to guide their transformation for greater climate security.

In July 2021, heavy and prolonged rainfall in the German states of North Rhine-Westphalia, Rhineland-Palatinate, Bavaria and Saxony led to destruction of infrastructures and buildings as well as injuries, missing persons and fatalities on a previously unimaginable scale. In 2018 and 2019, on the other hand, agriculture, forests, surface waters and groundwater, as well as people and ecosystems, suffered the enormous consequences of prolonged drought and heat. Recent climate studies show that the likelihood of both extremes will increase.

Each extreme weather event in itself can be existentially threatening, and recent flooding events in particular have been associated with unsustainable damage to life and limb, and loss of material, non-material and irreplaceable cultural values. This makes it all the more important to learn the right lessons. It is too early to draw comprehensive conclusions from this particular event: more detailed data and analysis are needed to better understand the mechanisms and factors that lead to these enormous humanitarian and financial impacts of extreme events, including hydrological processes, early warning and risk prevention issues, and vulnerability and land use. Only on this basis can informed goals and action requirements be derived for better and more future-proof development of communities and cities. This statement is intended to initiate a joint discussion process. Climate change poses enormous challenges for municipalities and cities in particular. Therefore, we need to work together to transform cities and towns, buildings and infrastructures, and ecosystems, and adapt to new weather dynamics.

It is time to launch a large-scale climate adaptation program, similar to climate protection. We need to further strengthen risk management of weather extremes and civil protection, as well as strategic planning in municipalities and cities. The goal must be to place the climate security of municipalities and cities on a new foundation. This will require further improvement of our knowledge base, but also cooperation among all stakeholders, including federal and state policymakers and agencies, private companies, associations, and individuals on the ground.

Five principles for climate-proof cities and communities

In the following, we present key principles that should guide the transformation of cities and communities to increase their climate resilience. The principles proposed here are well established in the professional community. Many of the demands were already made public after the great floods of 1993 and 1995 on the Rhine, or in the aftermath of the destructive floods of 2002 and 2013. This statement is intended to underscore their importance once again. The principles go beyond municipal and city boundaries, as many measures have an impact in cities but need to be decided and implemented at other spatial or federal levels. The principles are intended to help cities and towns prioritize climate security more effectively. However, solutions must always be developed in context. The challenges in the low mountains with its many small river basins are different from those in the lowlands. While some principles should be addressed immediately and implemented promptly (e.g., early warning and population protection), others can only be implemented over the longer term (restructuring infrastructure systems, increasing the storage capacity of landscapes). However, it is true that the foundations for longer-term transformation processes must also be laid in a timely manner.

The time to act is now.

Improve early warning systems and strengthen population protection:

Even for smaller river basins, it is important to improve the forecasting of flood waves and to establish reliable warning systems. In addition to the development of robust forecasting models, it is essential to establish permanent and reliable communication with representatives of cities and municipalities as well as local citizens. Only a warning that people understand and trust will lead to the desired actions.

Increase sponge capacity and storage capability:

In addition to established protection solutions, such as dikes, walls, and polders, there is an increased need to design communities, cities, and landscapes like sponges and improve water retention in the landscape. Every cubic meter of water that is not discharged into streams and rivers via the sewer system helps flatten flood waves, but cannot prevent them, as in the 2021 events. Therefore, it is necessary to increase the water retention and storage capacity of floodplains, forest and agricultural landscapes, but also in more densely populated areas through additional green and open spaces. Especially for extreme precipitation, additional storage areas and green infrastructures must be designed in such a way that they are also prepared to serve as emergency waterways in the event of an emergency. A high storage capacity for water helps not only in times of flood, but also in times of drought.

Enforce climate assessment of critical infrastructure:

In the rehabilitation, post-disaster reconstruction, and new construction of public infrastructures and buildings - especially so-called critical infrastructures - it is important to assess the consequences of climate change and renew design values accordingly. This includes consideration of cascading effects from disruption of utilities in infrastructure systems. Infrastructures (supply of water, electricity, etc.), the backbone of our modern society, must be designed to function in extreme weather or allow appropriate fallback options. It is unacceptable, especially during a crisis, for necessary communication networks, medical services and facilities to fail because they are not adequately prepared for such extreme events.

Promote climate resilience of buildings:

When rebuilding, constructing new buildings or renovating existing ones, it is important to consider the climate safety of buildings from the outset and to raise the standard of protection, especially of facilities that house particularly vulnerable groups such as children, senior citizens or people with disabilities. Similar to energy-efficient renovation, this requires financial support and incentive instruments as well as the establishment of precaution-oriented insurance premiums. Appropriate information about heavy rain or flood hazards should also be systematically provided and requested in building applications and property sales. It will not be enough to master future challenges in the building stock solely by appealing to the public or reactively.

The will to shape and implement is just as necessary as cooperation and solidarity:

The transformation requires the will to innovate and shape on the part of cities, municipalities, investors and private individuals, as well as the use of financing and incentive instruments on the part of the federal government and the states. There is a need for assertive planning instruments and coherent and standardized frameworks and procedures. Furthermore, the benefits and burdens of the transformation to climate-proof cities and municipalities must be shared in a spirit of solidarity. To cite just one example: Communities that create more space for water in the upper reaches of rivers will benefit only indirectly; but communities in the lower reaches will benefit directly, as the risk of flooding is reduced.

The full statement: www.ufz.de/index.php?de=48382

Authors:
Prof. Dr. Christian Kuhlicke (UFZ), Prof. Dr. Christian Albert (Ruhr University Bochum), Prof. Dr. Daniel Bachmann (Magdeburg-Stendal University of Applied Sciences), Prof. Dr. Jörn Birkmann (University of Stuttgart), Prof. Dr. Dietrich Borchardt (UFZ), Prof. Dr. Alexander Fekete (Cologne University of Applied Sciences), Prof. Dr. Stefan Greiving (TU Dortmund), Prof. Dr. Thomas Hartmann (TU Dortmund), Prof. Dr. Bernd Hansjürgens (UFZ), Prof. Dr. Robert Jüpner (TU Kaiserlautern), Prof. Dr. Sigrun Kabisch (UFZ), Prof. Dr. Kerstin Krellenberg (University of Vienna), Prof. Dr. Bruno Merz (GFZ), Prof. Dr. Roland Müller (UFZ), Prof. Dr. Dieter Rink (UFZ), Dr. Karsten Rinke (UFZ), Prof. Dr. Holger Schüttrumpf (RWTH Aachen), Prof. Dr. Reimund Schwarze (UFZ), Prof. Dr. Georg Teutsch (UFZ), Prof. Dr. Annegret Thieken (Uni Potsdam), Dr. Maximilian Ueberham (UFZ), Prof. Dr. Martin Voss (FU Berlin).

Text: UFZ press release