Storms (CLIM 005) - Assessment published Nov 2012
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Climate change (Primary topic)
Typology: Descriptive indicator (Type A – What is happening to the environment and to humans?)
- CLIM 005
Key policy question: What is the trend in extreme wind speeds across Europe?
- Storm location, frequency and intensity have shown considerable variability across Europe over the past century, making it difficult to identify clear trends. A recent reanalysis suggests that storminess has increased over the past century in northern and north-western Europe but this finding is not yet robust.
- Climate change projections for storms in the North Atlantic and Europe region show no clear consensus in either the direction of movement or the intensity of storm activity. However, a recent study involving 20 climate models projects enhanced extreme wind speeds over northern parts of central and western Europe, and a decrease in extreme wind speeds in southern Europe.
Trends in the extreme wind speeds in the period 1871-2008 based on reanalysis
Note: Trends in the annual 95th percentile of daily maximum wind speeds in the 20th century reanalysis data set (ensemble mean) during the period 1871–2008. The trend is given in the units of the interannual standard deviation and plotted only when significant. The coloured circles indicate trends in the number of 'gale days' (an index that represents the number of extremely windy days) over the period at the specific locations.
- Reanalysis suggests long-term upward trend in European storminess since 1871 provided by American Geophysical Union (AGU)
Projected changes in extreme wind speed based on GCM and RCM ensembles
Note: Ensemble mean of changes in extreme wind speed (defined as the 98th percentile of daily maximum wind speed) for A1B (2071–2100) relative to 1961–2000. Left: based on 9 GCMs. Right: based on 11 RCMs. Coloured areas indicate the magnitude of change (unit: m s−1), statistical significance above 0.95 is shown by black dots.
- Reanalysis suggests long-term upward trend in European storminess since 1871 provided by Natural Hazards and Earth System Sciences (NHESS)
Studies of past changes in extra-tropical storms have used a variety of methods for analysing their activity in the storm track regions, making it difficult to compare the results of different studies or to assess if there is any underlying climate change signal . Storm location and intensity in Europe has shown considerable variation over the past century. Locally, increases in maximum gust wind speeds have been observed over recent decades  but there is evidence for decreases in storm frequency since the 1990s (Ulbrich et al., 2009). Wind data at the local or regional levels can show a series of decreases and increases continuing over several decades. Long records of wind speed for various regions across Europe indicate that storminess has not significantly changed over the past 200 years . They also indicate relatively high levels of storminess in north-western European during the 1880s, followed by below average conditions between the 1930s and 1960s, a pronounced increase in storminess until the mid-1990s, and average or below activity afterwards. Somewhat similar patterns were observed in other parts of Europe.
Reanalyses for the time span 1871 to 2008 suggest an increasing long-term trend in storminess across north-western Europe. Storminess towards the end of the 20th century reached unprecedented values in the north-eastern North Atlantic, the North Sea and the Baltic Sea region (Figure 1) . However, somewhat different results were found in another reanalysis .
The simulation of extra-tropical cyclones in climate models remains a scientific challenge in spite of significant recent progress. Climate change projections show no clear consensus in either the direction of movement (poleward or equator-ward) or the intensity of extra-tropical cyclone activity in the North Atlantic region of western Europe . Earlier models showed some agreement on a future poleward shift in storm tracks, which would increase the frequency of the most intense wind events in higher latitudes . However, more recent projections with climate models that include a higher resolution stratosphere show an equator-ward shift in the Atlantic storm track which could double the predicted increase in winter rainfall over western and central Europe compared to other climate projections . It should be noted that the measure used to identify ‘storm tracks’ is different to that for ‘cyclone tracks’, so caution should be exercised when comparing these two measures.
Several studies suggest decreases in the number of storms in Europe but increases in the strongest, most damaging storms, in particular in northern and western Europe . A recent study involving ensemble simulations with 9 GCM and 11 RCM projects enhanced extreme wind speeds over northern parts of central and western Europe in most simulations and in the ensemble mean, and a decrease in extreme wind speeds in southern Europe  (see Figure 2).
 G.A. Meehl et al., “Global Climate Projections. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change” (Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA., 2007); U Ulbrich, G.C. Leckebusch, and J.G. Pinto, “Extra-tropical Cyclones in the Present and Future Climate: a Review,” Theoretical and Applied Climatology 96 (2009): 117–131, doi:10.1007/s00704-008-0083-8; X. L Wang et al., “Trends and Low-frequency Variability of Storminess over Western Europe, 1878–2007.,” Climate Dynamics (2011), doi:10.1007/s00382-011-1107-0.
 T. Usbeck et al., “Increasing Storm Damage to Forests in Switzerland from 1858 to 2007,” Agricultural and Forest Meteorology 241 (2010): 189–199.
 C Matulla et al., “European Storminess: Late Nineteenth Century to Present,” Climate Dynamics 31, no. 2–3 (2007): 125–130, doi:10.1007/s00382-007-0333-y.
 M. G. Donat et al., “Reanalysis Suggests Long-term Upward Trend in European Storminess Since 1871,” Geophysical Research Letters 38 (2011), doi:10.1029/2011GL047995.
 Wang et al., “Trends and Low-frequency Variability of Storminess over Western Europe, 1878–2007.”
 Meehl et al., “Global Climate Projections. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change”; Ulbrich, Leckebusch, and Pinto, “Extra-tropical Cyclones in the Present and Future Climate: a Review”; R McDonald, “Understanding the Impact of Climate Change on Northern Hemisphere Extra-tropical Cyclones,” Climate Dynamics 37 (2011): 1399–1425, doi:10.1007/s00382-010-0916-x.
 G. Gastineau and B. J. Soden, “Model Projected Changes of Extreme Wind Events in Response to Global Warming,” Geophysical Research Letters 36, no. L10810 (2009), doi:10.1029/2009GL037500.
 A.A. Scaife, “Climate Change Projections and Stratosphere–troposphere Interaction,” Climate Dynamics 1, no. 9 (2011), doi:10.1007/s00382-011-1080-7; McDonald, “Understanding the Impact of Climate Change on Northern Hemisphere Extra-tropical Cyclones.”
 J. G. Pinto et al., “Changes in Storm Track and Cyclone Activity in Three SRES Ensemble Experiments with the ECHAM5/MPI-OM1 GCM,” Climate Dynamics 29 (2007): 195–210, doi:10.1007/s00382-007-0230-4; Jens Boldingh Debernard and Lars Petter Røed, “Future Wind, Wave and Storm Surge Climate in the Northern Seas: a Revisit,” Tellus A 60, no. 3 (May 2008): 427–438, doi:10.1111/j.1600-0870.2008.00312.x; Paul M. Della-Marta and Joaquim G. Pinto, “Statistical Uncertainty of Changes in Winter Storms over the North Atlantic and Europe in an Ensemble of Transient Climate Simulations,” Geophysical Research Letters 36 (July 17, 2009): L14703, doi:10.1029/2009GL038557; Joaquim G. Pinto et al., “Factors Contributing to the Development of Extreme North Atlantic Cyclones and Their Relationship with the NAO,” Climate Dynamics 32, no. 5 (2009): 711–737, doi:10.1007/s00382-008-0396-4; Markus G. Donat et al., “European Storminess and Associated Circulation Weather Types: Future Changes Deduced from a Multi-model Ensemble of GCM Simulations,” Climate Research 42, no. 1 (May 20, 2010): 27–43, doi:10.3354/cr00853.
 M. G. Donat et al., “Future Changes in European Winter Storm Losses and Extreme Wind Speeds Inferred from GCM and RCM Multi-model Simulations,” Natural Hazards and Earth System Science 11, no. 5 (May 12, 2011): 1351–1370, doi:10.5194/nhess-11-1351-2011.
Future changes in European winter storm losses and extreme wind speeds
provided by Freie Universität Berlin
provided by Freie Universität Berlin
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