Natural Hazards and Extreme Events in the Baltic Sea region

Abstract

Abstract. A natural hazard is a naturally occurring extreme event with a negative effect on people and society or the environment. Natural hazards may have severe implications for human life and they can potentially generate economic losses and damage ecosystems. A better understanding of their major causes, probability of occurrence, and consequences enables society to be better prepared and to save human lives and to invest in adaptation options. Natural Hazards related to climate change are identified as one of the Grand Challenges in the Baltic Sea region. We here summarise existing knowledge of extreme events in the Baltic Sea region with the focus on past 200 years, as well as future climate scenarios. The events considered here are the major hydro-meteorological events in the region and include wind storms, extreme waves, high and low sea level, ice ridging, heavy precipitation, sea-effect snowfall, river floods, heat waves, ice seasons, and drought. We also address some ecological extremes and implications of extreme events for society (phytoplankton blooms, forest fires, coastal flooding, offshore infrastructures, and shipping). Significant knowledge gaps are identified, including the response of large scale atmospheric circulation to climate change, but also concerning specific events, for example, occurrences of marine heat waves and small-scale variability of precipitation. Suggestions for future research includes further development of high-resolution Earth System models, and the potential use of methodologies for data analysis (statistical methods and machine learning). With respect to expected impact of climate change, changes are expected for sea-level, extreme precipitation, heat waves and phytoplankton blooms (increase) and cold spells and severe ice winters (decrease). For some extremes (drying, river flooding and extreme waves) the change depends on the area and time period studies.