Climate change impacts and vulnerability in Europe 2016

Changes in the climate system
Map 3.12 Observed annual median and trend of the mean PHI over the period 1951–2010
-30°
Median
-20°
-10°
0°
10°
20°
30°
40°
50°
60°
70°
-30°
Trend
-20°
-10°
0°
10°
20°
30°
40°
50°
60°
70°
60°
60°
50°
50°
40°
40°
0°
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0°
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Observed annual median (left) and trend (right) of the mean Potential Hail Index (PHI) over the period 1951–2010
PHI
0 2.5 5 7.5 10 12.5 15 17.5 20 22.5 25
Outside
coverage
PHI
– 13 – 11 – 9 – 7 – 5 – 3 – 1 1 3 5 7
25 27.5 30 32.5 35 37.5 40 42.5 45 47.5 50
Not statistically significant
at the 5 % level
0
500 1 000 1 500km
Note:
Trends that are not significant at the 5 % level are cross-hatched. Significant trends are found only for values below a PHI of – 5 over the
period.
Source: Based on the logistic hail model (Mohr, Kunz, and Geyer, 2015) and reanalysis data from NCEP-NCAR (Kalnay et al., 1996).
Different RCMs have been used for assessing changes
in hailstorms at the national and sub-national
scales. A statistically significant downwards trend for
hailstones with diameters between 21 and 50 mm was
projected for the United Kingdom (Sanderson et al.,
2015). An increase in hailstorm frequency between
7 and 15 % for the period 2031–2045 compared with
1971–2000 was projected for south-west Germany
based on large-scale weather patterns (Kapsch et al.,
2012). Using the PHI and an ensemble of seven RCMs,
an increase in hail probability over most areas of
Germany was projected for the period 2021–2050
compared with 1971–2000 (Mohr, Kunz, and Keuler,
2015). The projected changes are largest in southern
Germany (values of almost 7 PHI). However, the
results are subject to large uncertainties, mainly
owing to low spatial resolution and convective
parametrisation schemes in regional climate models
(Fischer et al., 2014). Improving the convective
parametrisation schemes and increasing the spatial
resolution of models would improve the accuracy of
future hail projections.
Climate change, impacts and vulnerability in Europe 2016 | An indicator-based report
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