Introduction - Climate Change Impacts on Freshwater Ecosystems - page 11

these cannot be included and the output of the model is a reflection of the perceptions
of its perpetrators. The same is true of observational techniques and practical
experiments. Through choice of variables or of initial experimental conditions, the
conclusions are partly predetermined. Nonetheless, the failures of both models and
experiments to replicate reality are valuable indicators of what might be missing
from their designs. Such gaps are inexpensive to plug in modelling, if not in repeated
large-scale experiments, and the behaviour of whole river systems, regions or the
biosphere can ultimately be only the province of modelling.
The organization of Euro-limpacs reflected these advantages and uncertainties
by using a range of approaches. It had to build on existing experience and facilities
for the most part and could not achieve the ideal of using all the approaches on
a single habitat and a single aspect of climate change, even if such singularity
exists. Understanding increases nonetheless, even if tidy systems of operating are
inevitably confounded by the realities of funding and personal preferences. In the
end, opinion will depend on expert judgement based on all lines of evidence, for
precise prediction is only possible for simple systems, and nothing in earth system
science, with its underpinning of living organisms, not least the human ones, is
remotely simple.
Applications and the Water Framework Directive
Euro-limpacs included substantial components concerning the application of the
emerging scientific understanding. In Europe at present, water management is
very much focussed on the Water Framework Directive (EC/2000/60). The
Directive changes the previous approach to monitoring waters in Europe by
emphasising a whole-basin approach and by requiring determination and
restoration of ecological quality, as opposed simply to chemical water quality.
This must be done with respect to reference systems, which are defined in the
Directive as those unaltered or only negligibly altered by human activity. There
are few, if any, such systems left in Europe, so great has been the impact of large
population densities over several centuries, so determination of the schemes to
determine ecological quality is problematic. Nonetheless, tools for determining
the status of phytoplankton, aquatic plants, macroinvertebrates and fish are being
developed (UKTAG 2007), often using particular indicator species or families.
Climate change will inevitably upset these schemes as species become eliminated
or new ones move into previous cooler habitats.
There is also the underlying issue that since climate is now strongly influenced by
people, the establishment of reference pristine standards has become conceptually
impossible (Moss 2007, 2008). These issues are discussed in Chapter 9. The
Directive also requires restoration of aquatic systems to good ecological status,
defined as only slightly different from the high ecological status of the reference
standards. At this stage, the uncertainties become so great that schemes are
needed to help the appraisal of the available scientific information by agencies
and governments, and this issue is considered in Chapter 11.
Several reports have pointed out the economic consequences of climate change.
The Stern Report (2006) concluded that climate change could be mitigated at the