Scenarios of Change

In any assessment of the impact of climate change on freshwater ecosystems, scenarios are needed not only for climate but also for associated changes in land-use, nitrogen deposition and water resource demand. In REFRESH we will use a co-ordinated approach to develop a scenario framework based on the IPCC Special Report on Emissions Scenarios (SRES), which outlines different pathways for future socio-economic development and on the exploratory scenarios used by the Millennium Ecosystem Assessment. The scenario framework will be used to develop a series of coherent storylines which will then be further explored with stakeholders in terms of their consistency and relevance for eight case studies (demonstration catchments). The scenarios will drive the catchment models at each of these sites.

Climate change scenarios 

Detailed projections of future climate change are required to evaluate its impacts on functioning of aquatic ecosystems and to develop strategies for ecosystem management at the catchment scale. The most appropriate approach is that developed by the EU Framework 6 Project, ENSEMBLES, which generated an ensemble prediction system (i.e. multiple numerical predictions are conducted using slightly different initial conditions) for climate change based on the principal state-of-the-art, high resolution, global and regional Earth System Models. These allow an objective probabilistic estimate of uncertainty in future climate at the seasonal to decadal and longer timescales. In REFRESH we will initially use ENSEMBLES output to generate climate scenarios (using A1B scenarios from 1961-2100) for eight demonstration catchments.

Above: SRES (IPCC Special Report on Emission Scenarios) temperature change scenarios over the period 1990 to 2100. The globally averaged surface temperature is projected to increase by 1.4 to 5.8°C over the period 1990 to 2100. These results are for the full range of 35 SRES scenarios based on a number of climate models.

Source:IPCC Third Assessment Report "Climate Change 2001". IPCC Summary for Policymakers


Land-use change scenarios

Between the present and 2060 there are likely to be significant changes in land-cover as a result of both climate change and other socio-economic drivers. Although the uncertainty associated with projecting future land-cover is high, it is possible to construct scenarios that can be used to test the sensitivity of catchment models and explore the effectiveness of different adaptation and mitigation strategies (e.g. the construction of buffer strips or planting of woodland for biofuel). We propose to develop further the scenario tool LandSFACTS and apply it at the catchment scale to each of the REFRESH case study catchments.

Right: LandSFACTS demonstration output

The Macaulay Land Use Research Institute



Nitrogen deposition scenarios

Whilst sulphur dioxide emissions have fallen significantly across Europe over recent decades, emissions and deposition of nitrogen continue to remain high and remain a significant source of nutrient input to surface waters in many parts of Europe. Responsibility for emissions reductions across Europe lies with the Convention on Long-range Transboundary Air Pollution (CLTAP) and the European Monitoring and Evaluation Programme (EMEP) in Oslo. EMEP provides European-scale data that can be used for surface water modelling. The N deposition scenarios will provide a framework with which to assess effects of changing nitrogen deposition loads on adaptation, mitigation and restoration measures.

Galloway N deposition

Above: Spatial patterns of total inorganic nitrogen deposition (mg N/m2/y)

  1. 1860
  2. early 1990s
  3. 2050
Source: Galloway et al., (2004). Nitrogen cycles: past, present, and future. Biogeochemistry 70:153-226


Water resource scenarios

The future of Europe's freshwater ecosystems will not only be influenced by changes in climate, land-cover and pollution but also by future changes in water availability, especially the competition between the needs of ecosystems and the needs of human society for water supply. Scenarios for freshwater resources are being developed in Europe at different scales. At the continental scale the WaterGap model has been applied to quantify the changes in water availability and water use. At the catchment scale the SCENES project is developing scenarios using both quantitative modelling approaches and more qualitative storyline generation. REFRESH will draw upon the results from the SCENES and other European projects to review existing scenarios for water resources in Europe, highlight uncertainties for future water availability and vulnerable ecosystems, and downscale scenarios for the eight demonstration catchments.

Left: WaterGAP model developed at the Center for Environmental Systems Research (CESR) of the University of Kassel 

Source: SCENES Web site