Climate change impacts and vulnerability in Europe 2016

Climate change impacts on environmental systems
An improved understanding of how climate change
will affect species interactions in novel communities
established under a novel climate can be utilised
to assess the extinction risk of species of particular
conservation concern. It will also enhance our ability
to assess and mitigate potential negative effects on
ecosystem functions and services. Despite increasing
knowledge of the effects of climate change on pairwise
species interactions and on complete ecological
networks, quantitative assessments of these effects are
still lacking.
Past trends
A wide variety of plant and animal species in Europe
have moved northwards and uphill during recent
decades. Mountain top floras across Europe have
shown significant changes in species composition
between 2001 and 2008, with cold-adapted species
decreasing and warm-adapted species increasing
in number (Gottfried et al., 2012). On average,
most species have moved uphill. These shifts have
had opposing effects on the species richness of
summit floras in boreal-temperate mountain regions
(+ 3.9 species on average) and Mediterranean
mountain regions (– 1.4 species) (Pauli et al., 2012).
Data from Switzerland collected over an altitudinal
range of 2 500 m over a short period of eight years
(2003–2010) revealed significant shifts in communities
of vascular plants towards warm-dwelling species at
lower altitudes. However, rates of community changes
decreased with altitude (Roth et al., 2014). There is
further evidence of increases in the distribution range
due to climate change for several plant species (Berger
et al., 2007; Walther et al., 2007; Pompe et al., 2011).
The distributions of many terrestrial animals have
recently shifted to higher elevations. In Britain, the
distributions of spiders, ground beetles, butterflies,
grasshoppers and allies have shifted to higher
elevations at a median rate of 11 m per decade, and
to higher latitudes at a rate of 17 km per decade, but
with substantial variability across and within taxonomic
groups (Chen et al., 2011). These range shifts are partly
attributable to observed changes in climatic conditions,
but land-use and other environmental changes also
play a role (Schweiger et al., 2010, 2012). A study in
the Netherlands covering the period between 1932
and 2004 found that half of the investigated bird
species were overwintering significantly closer to
their breeding site than in the past, most likely due to
warmer winters (Visser et al., 2009). A long-term trend
analysis of 110 common breeding birds across Europe
(1980–2005, 20 countries) showed that species with the
lowest thermal maxima showed the sharpest declining
trends in abundance (Jiguet et al., 2010). In other words,
cold‐adapted species are losing territory most quickly.
Observations for most species show an expansion
at the leading edge (i.e. by expanding the range
northwards and/or uphill), whereas there is less
evidence for contractions at the trailing edge (i.e. at
the southern margins). However, bumblebees, which
are an important pollinator for agricultural and
natural ecosystems, showed a different response
to the observed warming in recent decades. They
suffered from strong range contractions at their
southern margins of up to 300 km in southern
Europe during the last 40 years, but failed to expand
northwards, thereby experiencing a substantial
compression of their range (Kerr et al., 2015). The
Community Temperature Index (CTI) is a measure
of the rate of change in community composition in
response to temperature change. As the CTI increases,
butterfly communities become increasingly composed
of species associated with warmer temperatures.
For example, the CTI of butterfly communities across
Europe has increased by 0.14 °C per decade from
1970 to 2007. However, temperature has increased by
0.39 °C per decade in the same period, that is, almost
three times faster than the butterfly community could
move northwards (van Swaay et al., 2008). The finding
that the movement of animal species is unable to keep
pace with climate change has been confirmed in an
analysis of the CTI of several thousand local bird and
butterfly communities across Europe (see Map 4.15)
(Devictor et al., 2012).
A comprehensive review study on amphibians and
reptiles found that 20 out of the 21 amphibian and
four out of the five reptilian species assessed in Europe
were already affected by climate change. The reported
effects were negative, mainly through population
declines, reductions in habitat suitability, and reduced
survival and range sizes, in more than 90 % for
amphibians and in more than 60 % for reptiles (Winter
et al., 2016). A review study on ducks (Anatidae), which
are major elements of wetland biodiversity, reports
shifts in winter distribution range and phenology.
Nevertheless, a phenological mismatch between
the periods of peak energy requirements for young
and peak seasonal food availability was not found in
general with regard to ducks (Guillemain et al., 2013).
The contribution of the Arctic to global biodiversity is
substantial, as the region supports globally significant
populations of birds, mammals and fish. The Arctic
Species Trend Index (ASTI) has been tracking trends in
306 Arctic species. An analysis of the ASTI over 34 years
(1970–2004) has shown that the abundance of High
Arctic vertebrates declined by 26 % whereas Low Arctic
vertebrate species increased in abundance. Sub-Arctic
species did not show a trend over the whole time
period, but seem to have declined since the mid-1980s
(McRae et al., 2010).
168 Climate change, impacts and vulnerability in Europe 2016 | An indicator-based report