Climate change impacts and vulnerability in Europe 2016

Climate change impacts on environmental systems
Map 4.4
Trend in relative sea level at selected European tide gauge stations
-30°
-20°
-10°
0°
10°
20°
30°
40°
50°
60°
70°
Trend in relative sea level at
selected European tide gauge
stations, 1970–2014
mm/year
< – 4
– 4 to – 3
– 3 to – 2
– 2 to – 1
– 1 to – 0.5
– 0.5 to 0.5
0.5 to 1
1 to 2
2 to 3
3 to 4
> 4
60°
50°
50°
Outside coverage
40°
40°
0 500 0° 1000 150010°
km
20°
30°
40°
Note:
These measured trends for 1970–2014 are not corrected for local land movement. No attempt has been made to assess the validity of
any individual fit, so results should not be treated as suitable for use in planning or policymaking. Geographical coverage reflects the
reporting of tide gauge measurements to the Permanent Service for Mean Sea Level (PSMSL).
Source: Holgate et al., 2012; PSMSL, 2016.
Past trends: extreme sea level along the European
coastline
Producing a clear picture of either past changes or
future projections of extreme high water levels for
the entire European coastline is a challenging task
because of the impact of local topographical features
on surge events. While there are numerous studies
for the North Sea coastline, fewer are available for the
Mediterranean Sea and the Baltic Sea, although this
situation is starting to improve.
Extreme sea levels show pronounced short- and
long-term variability. A recent review of extreme
sea level trends along European coasts concluded
that long-term trends are mostly associated with
the corresponding mean sea level changes. Changes
in wave and storm surge climate mostly contribute
to interannual and decadal variability, but do not
show substantial long-term trends (Weisse et al.,
2014). When the contribution from local mean sea
level changes and variations in tide are removed
from the recent trends, the remaining effects of
changes in storminess on extreme sea level are much
smaller or even no longer detectable (Menéndez
and Woodworth, 2010; Hov et al., 2013; Weisse et al.,
2014). Additional studies are available for some
European coastal locations, but these typically focus
on more limited spatial scales (Araújo and Pugh, 2008;
Haigh et al., 2010; Marcos et al., 2011; Dangendorf
et al., 2014). The only region where significant
increases in storm surge height were found during
the 20th century is the Estonian coast of the Baltic Sea
(Suursaar et al., 2009).
In conclusion, while there have been detectable
changes in extreme water levels around the European
coastline, most of these are the result of changes in
local mean sea level. The contribution from changes
in storminess is currently small in most European
locations and there is little evidence that any trends
can be separated from long-term natural variability.
128 Climate change, impacts and vulnerability in Europe 2016 | An indicator-based report