Multi-hazards in Scandinavia: impacts and risks from compound heatwaves, droughts and wildfires

Abstract. In the summer of 2018, large parts of Scandinavia faced record-breaking heat and drought, leading to increased mortality, agricultural water shortages, hydropower deficits, and higher energy prices. The 2018 heatwave coupled with droughts leading to wildfires are described as multi-hazard events, defined as compounding, cascading or consecutive events. Climate change is driving an increase in heat-related events and, subsequently, shows the necessity to prepare for such hazards, and to assess suitable mitigation strategies. To better understand the interplay of heatwaves, droughts, and wildfires across sectors, and to support disaster risk management in multi-hazard settings, we analyze their occurrence in Scandinavia using a spatial assessment of compound events. To assess their potential direct and indirect economic impacts we use the global Computable General Equilibrium (CGE) model GRACE (Global Responses to Anthropogenic Changes in the Environment) and the 2018 heatwave-drought period as a baseline to map multi-hazard risk. We find that multi-hazard events are pronounced in the summer months in Scandinavia and the 2018 multi-hazard events did not occur in isolation. The 2018 multi-hazard events led to a 0.08 % GDP drop in Scandinavia, with forestry experiencing a 3.04 % decline, affecting agriculture, electricity, and forestry exports, which dropped by 29.39 %, impacting Europe's trade balance. This research shows the importance of ripple effects of multi-hazards, specifically compound heatwave, drought and wildfire, and that forest management and a better understanding of their direct and indirect societal impacts are vital to reducing the risks of heat-related multi-hazards in vulnerable areas.