Climate change impacts and vulnerability in Europe 2016

Climate change impacts on environmental systems
having advanced by 5.9 days and fruiting by 3.2 days
over the period 1943–2003, whereas leaf senescence
was delayed on average by 1.2 days (Gordo and Sanz,
2006b). For plants, a medium spring advancement of
four to five days per 1 °C increase has been observed
in Europe (Bertin, 2008; Estrella et al., 2009; Amano
et al., 2010). Short warm and cold spells also can
have a significant effect on phenological events, but
this depends strongly on their timing and the species
(Koch et al., 2009; Menzel et al., 2011).
Remote sensing data can support the estimation of
the trend of phenological phases over large areas.
Continental-scale change patterns have been derived
from time series of satellite-measured phenological
variables (1982–2006) (Ivits et al., 2012). North-eastern
Europe showed a trend towards an earlier and
longer growing season, particularly in the northern
Baltic areas. Despite the earlier leafing, large areas
of Europe exhibited a rather stable season length,
indicating that the entire growing season has shifted
to an earlier period. The northern Mediterranean
displayed on average a shift in the growing season
towards later in the year, while some instances of
earlier and shorter growing seasons were also seen.
The correlation of phenological time series with
climate data shows a cause-and-effect relationship
over the semi-natural areas. In contrast, managed
ecosystems have a heterogeneous change pattern
with less or no correlation with climatic trends. Over
these areas, climatic trends seemed to overlap in a
complex manner, with more pronounced effects of
local biophysical conditions and/or land management
practices. One study demonstrated that the growing
season was starting earlier between 2001 and 2011 for
the majority of temperate deciduous forests in western
Europe, with the most likely cause being regional spring
warming effects experienced during the same period
(Hamunyela et al., 2013).
A combination of ground observations and the
Normalized Difference Vegetation Index (NDVI) both
indicated that spring phenology significantly advanced
during the period 1982–2011 in central Europe. The
average trend of 4.5 days advancement per decade
was not uniform and weakened over the last decade
investigated, where ground observations and NDVI
observations showed different trends (see Figure 4.16).
One possible explanation for the weakening trend from
2000 to 2010 is the response of early spring species to
the cooling trend in late winter during that time frame
(Fu et al., 2014). However, while individual studies find
good agreement between in situ observations and
experimental warming, a meta-analysis (Wolkovich et al.,
2012) suggests that experiments can substantially under
predict advances in the timing of flowering and leafing of
plants in comparison with observational studies.
The phenology of numerous animals has advanced
significantly in response to recent climate change (Dunn
and Møller, 2014). Several studies have convincingly
demonstrated that the life-cycle traits of animals are
strongly dependent on ambient temperatures, in
both terrestrial and aquatic habitats (e.g. Robinet and
Roques, 2010; Schlüter et al., 2010; Tryjanowski et al.,
2010; Cook et al., 2012; Bowler et al., 2015). Mostly, the
observed warming leads to an advanced timing of life
history events. For example, temporal trends for the
appearance dates of two insect species (honey bee, Apis
mellifera, and small white butterfly, Pieris rapae) in more
than 1 000 localities in Spain have closely followed
variations in recorded spring temperatures between
1952 and 2004 (Gordo and Sanz, 2006b).
The predicted egg-laying date for the pied flycatcher
(Ficedula hypoleuca) showed significant advancement
between 1980 and 2004 in western and central Europe,
but delays in northern Europe, both trends depending
on regional temperature trends in the relevant season
(Both and Marvelde, 2007). Data from four monitoring
stations in south to mid-Norway of nest boxes of the
pied flycatcher from 1992 to 2011 show, contrary to the
regional temperature estimated trends, that there were
no significant delays in the egg-laying date for the pied
flycatcher, but there was an annual fluctuation, making
a rather flat curve for the median over these years
(Framstad, 2012).
Two studies on Swedish butterfly species showed that
the average advancement of the mean flight date was
3.6 days per decade since the 1990s (Navarro-Cano
et al., 2015; Karlsson, 2014). Of the 66 investigated
butterfly species, 57 showed an advancement of the
mean flight date, which was significant for 45 species.
A study from the United Kingdom found that each
of the 44 species of butterfly investigated advanced
its date of first appearance since 1976 (Diamond
et al., 2011). A study indicated that average rates
of phenological change have recently accelerated
in line with accelerated warming trends (Thackeray
et al., 2010). There is also increasing evidence about
climate‐induced changes in spring and autumn
migration, including formerly migratory bird species
becoming resident (Gordo and Sanz, 2006a; Jonzén
et al., 2006; Rubolini et al., 2007; Knudsen et al., 2011).
Warmer temperatures shorten the development
period of European pine sawfly larvae (Neodiprion
sertifer), reducing the risk of predation and potentially
increasing the risk of insect outbreaks, but interactions
with other factors, including day length and food
quality, may complicate this prediction (Kollberg et al.,
2013). Warmer temperatures also extend the growing
season. This means that plants need more water to
keep growing or they will dry out, increasing the risk of
164 Climate change, impacts and vulnerability in Europe 2016 | An indicator-based report