Climate change impacts and vulnerability in Europe 2016

Climate change impacts on environmental systems
system. Currently, EU-wide soil indicators are (partly)
based on estimates and modelling studies, most of
which have not yet been validated. It is still common
to use precipitation (sometimes combined with
evaporation-based indicators, such as the SPI or the
Palmer Drought Severity Index) to describe changes
in soil moisture, despite the high sensitivity of the
assessment to the specific method used (Samaniego
et al., 2013).
Generally, observations for popular species groups
such as vascular plants, birds, other terrestrial
vertebrates and butterflies are much better than for
less conspicuous and less popular species. Similarly,
owing to (1) extensive existing networks, (2) a long
tradition and better means of detection of rapid
responses of the organisms to changes, and (3)
general knowledge, phenological changes are better
observed and recorded than range shifts. Projections
of climate change impacts on phenology rely crucially
on the understanding of current processes and
responses. For most cases, only a few years of data
are available and they do not cover the entire area of
the EU but are restricted to certain well-monitored
countries with a long tradition, for example, in the
involvement of citizen scientists. Based on the short
time series, the quantification of impacts and their
interpretation thus has to rely on assumptions (Singer
and Parmesan, 2010). One of the greatest unknowns
is how quickly and closely species will alter their
phenology in accordance with a changing climatic
regime (van Asch et al., 2007; Singer and Parmesan,
2010). Even experimental studies seem to be of little
help, as they notoriously tend to underestimate the
effects of climate change on changes in phenology
(Wolkovich et al., 2012).
Observing range shifts (and projecting responses
to climate change) crucially depends on good
distributional data, which is better for popular groups
of species than for other species. There are also large
regional differences in the quality of observational data,
with better data generally available in northern and
western Europe than in southern Europe. As neither
data quality nor lack of data is properly recorded,
the true quality of projections of range shifts, as
well as the likelihood of unobserved range shifts, is
largely unknown (Rocchini et al., 2011). Some studies
found unexpected results, such as range shifts of
terrestrial plants towards lower elevations, which may
be explained by the characteristics of local climate
change or by taxonomic and methodological shortfalls
identified in the simulation of range shifts (Lenoir and
Svenning, 2015).
Species distribution models (also known as habitat
models, niche models or climate envelope models)
suffer from a variety of limitations because species are
currently not in equilibrium with climate, and because
species dispersal and biotic interactions are largely
ignored (Bellard et al., 2012; Zarnetske et al., 2012).
Furthermore, climate change projections for Europe
include climate conditions for which no analogue
climate was available for the model calibration. Some
models still do not include such climates, which may
lead to misinterpretations of projected changes.
When documenting and modelling changes in soil,
biodiversity and forest indicators, it is not always
feasible to track long-term changes (signal) given
the significant short-term variations (noise) that may
occur (e.g. seasonal variations of soil organic carbon
as a result of land management). Therefore, detected
changes cannot always be causally attributed to
climate change. Human activity, such as land use and
management, can be more important for terrestrial
ecosystem components than climate change, both for
explaining past trends and for future projections.
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