Storms (CLIM 005) - Assessment published Nov 2013
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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 show considerable variability across Europe over the past century, such that no clear trends are apparent. 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 from a recent climate model ensemble study show a small increase in extreme wind speeds over northern parts of central and western Europe, and a decrease in southern Europe. The results of studies into changes in winter storm tracks show no clear signal.
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, but Northern Hemisphere storm tracks and intensity have likely shifted northwards since at least 1970 [i]. 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 [ii]. 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 [iii]. They also indicate relatively high levels of storminess in north-western Europe 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.
A single reanalysis study for the period 1871 to 2008 suggests an increasing trend in storminess across north-western Europe, with storminess towards the end of the 20th century reaching its highest values in the north-east North Atlantic, the North Sea and the Baltic Sea region (Figure 1) [iv]. However from other research there is evidence that both conflicts and agrees with this result [v]. Thus the results presented here have low confidence, especially over the question of the robustness of the reanalysis results for extreme wind speeds before the middle of the 20th century [vi].
The simulation of extra-tropical cyclones in climate models remains a scientific challenge in spite of significant recent progress in modelling techniques. Climate change projections show no clear consensus in the direction of movement (poleward or equator-ward) of extra-tropical cyclone activity in the North Atlantic region of western Europe [vii]. Earlier models showed some agreement on a future poleward shift in storm tracks, which would also increase the frequency of the most intense wind events in higher latitudes [viii]. 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 [ix]. 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 [x]. The most recent research with a multi-model ensemble projects a small increase in the magnitude of the strongest winter storms over northern parts of central and western Europe, and a decrease in southern Europe, under a high emissions scenario (Figure 2) [xi]. The results are largely consistent with those of a recent study based on the GCM projections underlying the IPCC Fifth Assessment Report [xii].
[i] D. L. Hartmann, A. M. G. Klein Tank, and M. Rusticucci, “Observations: Atmosphere and Surface (Final Draft Underlying Scientific-Technical Assessment),” in Climate Change 2013: The Physical Science Basis (Intergovernmental Panel on Climate Change (IPCC), 2013), Chapter 2, http://www.climatechange2013.org/images/uploads/WGIAR5_WGI-12Doc2b_FinalDraft_Chapter02.pdf.
[ii] Ulbrich, Leckebusch, and Pinto, “Extra-Tropical Cyclones in the Present and Future Climate: A Review”; T. Usbeck et al., “Increasing Storm Damage to Forests in Switzerland from 1858 to 2007,” Agricultural and Forest Meteorology 241 (2010): 189–199.
[iii] 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.
[iv] 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.
[v] S. Brönnimann et al., “Extreme Winds at Northern Mid-Latitudes since 1871,” Meteorologische Zeitschrift 21, no. 1 (February 1, 2012): 13–27, doi:10.1127/0941-2948/2012/0337; 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; Xiaolan L. Wang et al., “Is the Storminess in the Twentieth Century Reanalysis Really Inconsistent with Observations? A Reply to the Comment by Krueger et Al. (2013b),” Climate Dynamics (n.d.): 1–13, accessed October 24, 2013, doi:10.1007/s00382-013-1828-3.
[vi] Oliver Krueger et al., “Inconsistencies between Long-Term Trends in Storminess Derived from the 20CR Reanalysis and Observations,” Journal of Climate 26, no. 3 (February 2013): 868–874, doi:10.1175/JCLI-D-12-00309.1; Wang et al., “Is the Storminess in the Twentieth Century Reanalysis Really Inconsistent with Observations?”.
[vii] Hartmann, Klein Tank, and Rusticucci, “Observations: Atmosphere and Surface (Final Draft Underlying Scientific-Technical Assessment).”
[viii] 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.
[ix] 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; Adam A. Scaife et al., “Climate Change Projections and Stratosphere–troposphere Interaction,” Climate Dynamics 38, no. 9–10 (May 27, 2011): 2089–2097, doi:10.1007/s00382-011-1080-7.
[x] Pinto et al., “Changes in Storm Track and Cyclone Activity in Three SRES Ensemble Experiments with the ECHAM5/MPI-OM1 GCM”; 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; Giuseppe Zappa et al., “A Multimodel Assessment of Future Projections of North Atlantic and European Extratropical Cyclones in the CMIP5 Climate Models*,” Journal of Climate 26, no. 16 (2013): 5846–5862, doi:10.1175/JCLI-D-12-00573.1.
[xi] 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; Hartmann, Klein Tank, and Rusticucci, “Observations: Atmosphere and Surface (Final Draft Underlying Scientific-Technical Assessment).”
[xii] Zappa et al., “A Multimodel Assessment of Future Projections of North Atlantic and European Extratropical Cyclones in the CMIP5 Climate Models*.”
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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