Supporting climate risk management with synthetic weather extremes

Climate change adaptation actions are vital in cities to prepare and adapt to advancing climate change, especially rapidly changing probabilities of extreme weather events. Although especially in Europe many cities have generated adaptation and climate risk management plans and improved decision-support also with respect to weather and climate risks, there is still much to do. Often, risk management actions are strongly activated only after experiencing negative impacts, for example, related to a severe flood causing substantial damages or even losses of lives. In a perfect world, however, in risk management all potential risks should be considered already beforehand, and either adapt to them or at least acknowledge these possible risks.

To support the Finnish cities’ preparedness for possible, yet not previously observed extreme weather events, the project LONGRISK designed a decision platform for strategic risk management, which generated an extensive dialogue between decision-makers and experts in three Finnish pilot cities (Helsinki, Tampere, Kotka). One of the main objectives of the project was to generate a “climate risk monitoring Dashboard” that demonstrates possible near-future extreme weather episodes and their impacts. More specifically, the Dashboard consisted of the synthetic reposition of the Copenhagen 2011 extreme cloudburst over each pilot city including the simulated flood impacts.

The Dashboard was a key tool in persuading city policymakers representing also the highest decision level (e.g. the Mayor) to engage in a Situation Room exercise, i.e., an internal dialogue especially on the possible gaps in their present adaptation level and chain of communication and decision-making. As a result, and especially due to the intensive internal dialogue, the decision-makers recognized their main vulnerabilities and weaknesses and generated a list of action items for further development.

This study presents the overall procedure of generating the Dashboard and running the Situation Rooms. Also, we present the method for generating the synthetic extreme weather events, such as the repositioned Copenhagen cloudburst and related urban flood simulations that are congruent with the climatological statistics and with CMIP6 climate projections.