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.

Climate Change in the Baltic Sea Region: A Summary

“…Events in the Baltic Sea region (Rutgersson et al, 2021): extremes in wind, waves, and sea level, sea-effect snowfall, river floods, hot and cold spells in the atmosphere, marine heat waves, droughts, ice seasons, ice ridging, phytoplankton blooms and some implications of extreme events for society (including forest fires, coastal flooding, offshore wind mills and shipping). (Weisse et al, 2021): sea level dynamics and coastal erosion in past and future climates.…”

“…All data sets presented here are publicly online available. For further details on various datasets, the reader is referred to Rutgersson et al (2021).…”

“…Extreme air temperatures can be high or low, but extended periods of extreme temperatures (spells or waves) are often the most influential. Averaged over land areas, warm spell duration increased during recent decades (Rutgersson et al, 2021). For some regions, the average annual days defined as warm spells increased from 6-8 to 14 during recent decades.…”

Coupled regional Earth system modeling in the Baltic Sea region

“…Apart from the representation of mean climate, many airsea coupling processes are important in generating hazardous events such as extreme precipitation, storm track paths or flooding (see also Rutgersson et al, 2021). Often these events are generated remotely over the open ocean and, thus, require a realistic representation of the ocean's surface.…”

“…Such a framework allows for modeled natural and managed ecosystems to respond to climate and environmental change and to influence local and regional climate through the biophysical feedback mechanisms outlined above. RCA-GUESS was the first published and evaluated RESM (Smith et al, 2011) to include the terrestrial biosphere as an integral dynamic component, and it couples LPJ-GUESS to the RCA3 RCM (Samuelsson et al, 2011). In its RCA-GUESS configuration, LPJ-GUESS is driven by the daily mean temperature, soil water content, precipitation and downward shortwave radiation simulated by RCA3, and the CO 2 concentration is read from the same source used to force RCA.…”