Modelling Catchment-Scale Responses to Climate Change - Climate Change Impacts on Freshwater Ecosystems - page 258

Secondly, a methodology has been developed to convert outputs of temperature
and precipitation from GCMs to values appropriate for use in the catchment-
scale models. This standardized method for downscaling can be used with the
INCA family of models to assess the likely impacts of climate change on freshwater
quality (see “The Euro-limpacs modelling strategy” Section).
And thirdly, a semi-automated sensitivity and uncertainty tool has been
developed that can be used to assess the effect of different parameter values on
model performance and quantify the spread of modelled outcomes when making
projections of future flow and water quality conditions.
The techniques of converting GCM output to meaningful inputs for catchment-
scale models and the techniques of sensitivity and uncertainty analysis are not new,
and other methods of uncertainty analysis are widespread. The novelty is the creation
of a methodology that can now be consistently applied to river systems across Europe
to assess changes in the flow and water quality for a broad range of water quality
indicators, derive precipitation and temperature inputs to models in a clearly defined
way and use a common methodology in sensitivity and uncertainty analysis that can
be applied allowing comparison of the results at the pan-European scale.
The questions posed in the introduction can be mainly answered affirmatively.
Models are never going to provide exact and unequivocal predictions of the
effects of climate change on freshwater ecosystems. But the models developed
during the Euro-limpacs project have been able to make useful predictions,
qualified as they are by estimates of uncertainty. Models have also been used to
explore plausible outcomes, to identify fruitful areas for further research so that
future predictions will be less uncertain, to increase understanding of processes
and to explore management options. Predictions concerning hydrology seem to
be better founded than those concerning water quality, and ecological predictions
are the most uncertain of all, reflecting a trend of increasing complexity and
reduced understanding. There is still much research to do before we are close to
being able to predict the effects of climate change on aquatic ecosystems.
References
Andersen, H.E., Kronvang, B., Larsen, S.E., Hoffmann, C.C., Jensen, T.S. & Rasmussen, E.K. (2006)
Climate-change impacts on hydrology and nutrients in a Danish lowland river basin. Science of the
Total Environment , 365 , 223-237.
Araújo, M.B. & New, M. (2007) Ensemble forecasting of species distributions. Trends in Ecology and
Evolution , 22 , 42-47.
Arnell, N.W. & Reynard, N.S. (1997) The effects of climate change due to global warming on river flows
in Great Britain. Journal of Hydrology , 183 , 397-424.
Bernal, S., Butturini, A., Riera, J.L., Vazquez, E. & Sabater, F. (2004) Calibration of the INCA Model in a
Mediterranean forested catchment: the effect of hydrological inter-annual variability in an intermittent
stream. Hydrology and Earth System Sciences , 8 , 729-741.
Berry, P.M., Dawson, T.P., Harrison, P.A. & Pearson, R.G. (2002) Modelling potential impacts of climate
change on the bioclimatic envelope of species in Britain and Ireland. Global Ecology and Biogeography ,
11 , 453-462.
Beven, K. (2006) A manifesto for the equifinality thesis. Journal of Hydrology , 320 , 18-36.
Bjerkeng, B. (1994). Eutrophication Model for the Inner Oslo Fjord . Report 2: Description of the contents
of the model [in Norwegian]. Report no. 3113. Norwegian Institute for Water Research, Oslo.