REFRESH – Adaptive Strategies to Mitigate the Impacts of Climate Change on European Freshwater Ecosystems | Umweltbundesamt

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. REFRESH will use a co-ordinated approach to develop a scenario framework based on the IPCC Special Report on Emissions Scenarios (SRES - IPCC Third Assessment Report "Climate Change 2001"), 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).

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 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.

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).

changes in water levels and flow regimes

1961-2100

The Project considers how freshwater ecosystems (rivers, lakes, reservoirs, and riparian wetlands) in Europe will change over the next fifty years and it uses a combination of novel experiments and modelling to generate the understanding and tools needed to implement an adaptive management strategy.

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.

One of the specific objectives of this project is to develop new indicator systems and vulnerability assessment methods for wetland ecosystems facing climate change.

REFRESH will evaluate the merits of various adaptation, mitigation and restoration methods to counteract effects of climate and land-use change on the structure and function of rivers. Existing strategies at the local scale in different European climate zone will be reviewed and the success rate and cost-effectiveness of projects according to water type and measure will be assessed. Differences in success rates for similar restoration methods across climatic zones, taking current land-use into consideration, will be highlighted. The main drivers of recovery of biodiversity and ecosystem structure and functioning in rivers will be identified. Additionally REFRESH will evaluate current lake adaptive management and restoration measures (reducing nutrient and organic matter load, reducing internal loading, biomanipulation) in relation to climate change. Predictive modelling will be applied to assess which strategies will be most successful in the future, given changes in temperature, water level fluctuations and nutrient loading. The predictions will be used to generate guidelines for climate-proof, adaptive and feasible restoration targets across Europe and provide recommendations for management of riparian wetlands.