Storms and storm surges in Europe (CLIM 005) - Assessment published Sep 2008
Climate change (Primary topic)
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)
- CLIM 005
Key policy question: .
- There has been considerable variation, but no clear long term trend in storminess in Europe. Storm frequency was relatively high during the late 19th and early 20th century; then decreased in central and northern Europe. The recent high level is similar to the late 19th century level of storminess.
- Despite the variation in storminess, water levels along most vulnerable European coastlines of the North Sea and Mediterranean Sea have shown no significant storm-related variation.
- Extra-tropical storm tracks are projected to move pole-wards, with consequent changes in wind, precipitation, and temperature patterns, continuing the broad pattern of observed trends over the past half-century.
- Climate models indicate a slight decrease in the number of storms and an increase of the strength of the heaviest storms.
- Projections to the end of the 21st century show a significant increase in storm surge elevation for the continental North Sea and south-east England.
Storm index for various parts of Europe 1881-2005
Note: Positive values of the index mean higher storminess.
Matulla, C.; Schöner, W.; Alexandersson, H.; von Storch, H. and Wang. X. L., 2007. European storminess: late nineteenth century to present. Climate Dynamics, DOI 10.1007/s00382-007-0333-y. See read free version: here.
Projected relative change of annual maximum daily mean wind speed between 1961-2000 and 2050 using different models
Note: Data are calculated for 10 m height using the + 2 oC scenario for 2050 (IPCC-SRES A1B emission scenarios) and the reference climate (1961-2000) from three similar models (left) and one different model, MIROCHi (right).
van den Hurk, B.; Klein Tank, A.; Lenderink. G.; van Ulden, A.; van Oldenborgh, G. J.; Katsman, C.; van den Brink, H.; Keller, F.; Bessembinder, J.; Burgers, G.; Komen, G.; Hazeleger, W. and Sybren Drijfhout, S., 2006. KNMI Climate Change Scenarios 2006 for the Netherlands, KNMI Scientific Report WR 2006-01, 3730 AE De Bilt.
Change in the height of a 50-year return period extreme water level event to the end of the 21st century for different scenarios
Note: The water level is measured relative to the present day tide, due to changes in atmospheric storminess, an increase in mean sea level and vertical land movements
Lowe, J. A. and Gregory, J. M., 2005. The effects of climate change on storm surges around the United Kingdom. Proceedings of the Royal Society of London. Series A: 363: 1313-1328.
Storminess in Europe has shown considerable variation over the past century, but with no clear long-term trend. This is illustrated by means of the storm-index time series (Figure 1), based on air-pressure data. These series show that storminess in north-western, northern and central Europe was relatively high during the late 19th and early 20th century; then decreased in central Europe and northern Europe. The subsequent rise in the late 20th century was most pronounced in north-western Europe, while slow and steady in central Europe. Most recent years have shown average or calm conditions (Matulla et al., 2007). On the local scale, station wind data can show different behaviour. Decreases and increases continuing over several decades can be seen at particular locations. For example a strong decrease in wind storms has been observed over the Netherlands during the past 40 years (Smits et al., 2005).
Evaluating high tide levels along the North Sea in the past century showed clear changes in mean levels (related to sea-level rise) but no storm-related variations (von Storch et al., 2002). Similarly, in the northern Adriatic Sea the trends for high sea levels and the subsequent occurrence of storm surges can not be associated with any trends in storminess (Lionello, 2005).
Extra-tropical storm tracks are projected to move pole-ward, with consequent changes in wind, precipitation, and temperature patterns, continuing the observed trends over the last half-century (IPCC, 2007a). The total number of storms is projected to decrease, but the strengths of the heaviest storms may increase, depending on the model used (see Figure 2 showing different regional maximum wind distributions with different models). Note that these projections are still very uncertain and model-dependent.
During historic times, storminess and large-scale temperature variations were mostly decoupled, but the projections show a closer relationship. Some projections, based on the high emissions IPCC SRES A2 scenario, show a related increase in temperature and the frequency of heavy storms in the North Atlantic Ocean. The future storminess in this region depends on projections of sea surface temperature, retreat of Arctic ice and changes in the air pressure field (Fischer-Bruns et al., 2005).
Projections of storm surges are closely connected with future storminess. The projections for the end of 21st century show a significant increase of storm surge elevations for the continental North Sea coast, by between 15 and almost 25 cm (Woth, 2005). For the UK coastline, a large increase in relative surge height is projected for the high IPCC SRES scenario A2 and the intermediate scenario B2, especially along the south-east coast of England, where the changes in storminess will have their largest effect and where the land is sinking most rapidly (Lowe and Gregory, 2005; Figure 3).
provided by Freie Universität Berlin
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