1. The Eawag Workshop on Climate and Water Preliminary summary of results and implications for bundling relevant future research at Eawag

2. Special thanks to the working group leaders: Jürg Beer (Global issues) Flavio Anselmetti (Palæolimnology) Bas Ibelings (Aquatic ecosystems) Ole Seehausen (Fish) Olaf Cirpka (Groundwater) Urs von Gunten (Drinking water and water technology) Andreas Klinke (Societal issues) and to all the rest of you who participated!

3. Brief history of the topic Preliminary summary of main results of workshop Some suggestions for common research Plenary discussion Summary

4. Climate and zooplankton, UK George & Harris (1985): Nature 316, 536-539. "Year-to-year fluctuations in the biomass of crustacean zooplankton in Lake Windermere are strongly correlated with variations in water temperature, but poorly correlated with the abundance of the dominant planktivorous fish.” Air and water temperatures in the Lake District are strongly related to the sea-surface temperature to the west of the UK, implying a large-scale climatic influence. "This represents the first conclusive evidence of climatologically induced variability in a freshwater planktonic system." George & Taylor (1995): Nature 378, 139. Zooplankton biomass related to position of the north wall of the Gulf Stream

5. Climate-related regional coherence Magnuson, Benson & Kratz (1990): Freshw. Biol. 23, 145-159. Lakes in N. Wisconsin connected by: (i) common climatic forcing (ii) groundwater flow "Coherence between lakes was greater for limnological variables directly influenced by climatic factors than for variables either indirectly affected by climate of complexly influenced by other types of factors"

6. “Lake 239” (ELA, Ontario), 1969-1988 Schindler, Beaty, Fee, Cruikshank, DeBruyn, Findlay, Linsey, Shearer, Stainton & Turner (1990): Science 250, 967-970.

7. EU projects (with Eawag involvement) Coordinated by Glen George EU FP4 project "REFLECT" (1998–2000) EU FP5 project "CLIME" (2001-2003) Coordinated by Rick Battarbee EU FP3 project "MOLAR" (1996-1999) EU FP5 project "EMERGE" (2000-2003) EU FP6 project "Euro-limpacs" (2004- 2009) Relevant international research networks (initiated by John Magnuson and coworkers) LTER (Long Term Ecological Research) LIAG (Lake Ice Analysis Group) GLEON (Global Lake Ecological Observatory Network)

8. Global aspects What contribution can we make to solving global-scale climate-change problems? 1)Work is already ongoing on global-scale problems relevant to climate change For example: - Greenhouse gases (CH 4 ) - Solar forcing (Be in Greenland ice) - Adapt approach to existing global-scale problems to allow for the expected impacts of climate change? E.g. SODIS; Arsenic in groundwater. 2)The predicted main changes are a shift in mean values and, more importantly, an increase in variability - Reconstruction of past climate change and “intelligent monitoring” of present climate change at carefully selected sites 3)“Space-for-time substitution” and “Space-for-space substitution” Climate change results in a horizontal shift of climate zones over hundreds to thousands of kilometres. Translated to altitude, the same shifts correspond merely to hundreds of metres. The selection of 3-4 ecosystems at different altitudes in the Alps would offer the opportunity to study large-scale climate shifts within Switzerland (analogues) 4)Water availability and water quality in mountain regions Many aspects apparently specific to the Alps are actually also relevant to other mountain regions: transfer of know-how.

9. Palæolimnology Using the past as the key to the future 1) Lake sediments enable us to quantify natural climate variability, thus allowing predicted changes to be put into historical perspective Warmer time windows in the Holocene can be used as analogues for future climate scenarios (How will the future be? Look into the past!) 2) Climate change as a driver of ecosystem change in the past Lake sediments archive various proxies that document past physical, chemical and biological changes in the ecosystem in response to various past climates. This allows the impact of past climate change on these ecosystems to be assessed. 3) A gap to be filled: past and future changes in precipitation The natural range in precipitation (extreme events/floods and background values) have so far not been quantified, although these are crucial in future climate scenarios and for the assessment of natural hazards. Investigation of critical proxies for precipitation. 4) Again: “space-for-space substitution” Climate change has a stronger impact at high latitudes than at low latitudes. The impact of past climates on a vertical gradient of environments (rather than a horizontal one) could be investigated in the Alpine area.

10. Aquatic ecosystems From monitoring to understanding, predicting and managing the effects of climate change on aquatic ecosystems 1) Monitoring - Set up and maintain ‘clever’ monitoring systems that will capture the true dynamics of changing aquatic ecosystems, e.g. community dynamics. (GLEON...) 2) Understanding - Which changes in water quality and in aquatic ecosystems can be demonstrably attributed to climate change? - What determines the resilience of the response of ecosystems to change? - What is the capacity of ecosystems to adapt? 3) Predicting Use a deepened understanding of the effects of climate change on aquatic ecosystems to improve, calibrate and validate ecosystem models. 4) Managing Incorporate the adaptive responses of society into the study of ecosystem change.

11. Fish Background, objectives and current limitations Objective of a research program “climate and fish”: Understanding and predicting responses of fish assemblages to climate change Current limitations: 1.Lack of quantitative data on fish communities in Swiss lakes and rivers 2.Limited understanding of relative importance of and interaction between abiotic and biotic climate-driven stressors 3.Limited understanding of potential responses of fish species to climate change Broad agreement that: 1.Fish communities are changing rapidly. Patterns are poorly documented, drivers are poorly understood. There are strong indications that climate change is an important driver. 2.Switzerland is a hotspot of diversity and endemism of cold-adapted fish species. Several have already become extinct 3.Switzerland is geographically uniquely positioned for research on climate change impacts on fish, and we think it is highly relevant to Eawag‘s mission

12. Fish An integrated programme “climate and fish” would include: 1.Literature analyses and formal meta-analyses, relying on data mostly from other regions of the world, but also Swiss grey literature. These would address a number of key issues that would guide the data collection strategy. 2.Generation of a time zero+ baseline data set on fish community composition and genetic diversity in the major Swiss lakes and rivers. 3.Establishment of long-term data series in a network of waters covering elevational gradients and the biogeographical regions. 4.Hypothesis-driven experimental work to quantify the potential of evolutionary response to climate change in key species. 5.Theoretical and quantitative ecological and genetic modelling to integrate these parallel approaches.

13. Groundwater The impact of climate and environmental change on aquifers 1) Direct impacts of climate change on groundwater bodies are probably less important than indirect impacts - Changes in land use, agricultural practice, legislation - Factor environmental change into integrated water resources management 2) In CH: Impact of droughts is more important than the impact of warming - Needed: Vulnerability study of Swiss aquifers 3) Key project in CH: Follow the process chain from environmental changes to groundwater quality - Needed: Well studied aquifer system + calibrated model - Hypothesis: Change in hydrology  change in groundwater hydrogeochemistry  threat to current practice of groundwater use 4) Eawag‘s contribution to climate and groundwater in semi-arid regions: Geogenic pollution in a changing climate

14. Drinking water and water technology issues 1) Changes in river discharge (proportion of wastewater) → Effect on groundwater quality? Upgrading of wastewater treatment? 2) Changes in agricultural practices (irrigation, changes in application of fertiliser, manure, pesticides) → Effects on groundwater quality and quantity 3) Changes in temperature and mixing regimes of lakes → Effect on phytoplankton and cyanobacterial population, taste and odour, cyanotoxins. Adequate treatment? 4) Institutional/organisational problems in coping with the effects of climate change on water supplies

15. Societal issues Governance and research approaches 1) Governance in Switzerland - Resilience and flexibility of current water management systems - Adequacy of current regulations and management practices (including monitoring) to tackle the relationship between water resources and climate - Integration of stakeholders to understand and deal with emerging problems better - Integrated water resource management 2) Governance in developing and transition countries - High vulnerability of urban water systems - Development of technological and organisational solutions - Capacity building and empowerment 3) Interdisciplinary and transdisciplinary research approaches 4) Involvement of Eawag with international bodies (e.g., WMO, IPCC, FAO, UNESCO, UNEP...)

16. Some common and important issues 1) Reconstructing the past and monitoring the present - “intelligent monitoring” (referring to human intelligence) and “clever monitoring” (referring to the capabilities of the monitoring system) 2) Understanding processes - because understanding is a prerequisite to robust modelling 3) Broadness of approach - interdisciplinary, international, cooperative, involving stakeholders and external partners 4) Distinguish between: (i) environmental change that is the direct result of climate change; (ii) environmental change that is the indirect result of climate change; and (iii) environmental change that is unconnected with climate change.

17. Some common and important issues 4) Distinguish between: (i) environmental change that is the direct result of climate change; (ii) environmental change that is the indirect result of climate change; and (iii) environmental change that is unconnected with climate change. Direct: - Interface between climate and aquatic physics (e.g., shifts in the heat balance of lakes and rivers; shifts in the phenology of ice and of mixing). But there are some direct biological and chemical effects (e.g. impact of changes in cloud cover on photosynthesis; impact of changing air temperature on pH in catchments). Indirect: - Interface between aquatic physics and other aquatic disciplines - climate is not directly involved. E.g. Impacts of higher water temperatures on phytoplankton (mesocosm experiments) or on fish habitats. Unconnected: - Impacts of urbanisation, new technologies, global and local economics, population shifts, legislation changes, agricultural practices etc. etc. etc..... Essentially unpredictable in the long term.

18. Some common and important issues 4) Distinguish between: (i) environmental change that is the direct result of climate change; (ii) environmental change that is the indirect result of climate change; and (iii) environmental change that is unconnected with climate change. So why should we bother studying the impacts of climate change on water resources when the impacts of other types of environmental change (e.g. social change) that are much less quantifiable are likely to be greater? - What we can predict, we should. - It is important to establish a “framework of thought” well in advance of the strongest impacts - i.e., to be intellectually prepared. The models (even intellectual, conceptual models) have to be in place in good time so they can be employed, refined and made more quantifiable closer to the time of impact, when the social changes are easier to predict than now.

19. Water resources as an endangered species  Agriculture  Industrial / urban / natural contamination  Conflicts: ecology  groundwater protection  Climate: quantity (spring water!) Quality (change in redox, input of nutrients, physical conditions, hygiene, etc...) Agriculture U-Chem Eco  GWP Eco, Surf, W+T Contamination Ing, Sandec, U-Chem, U-Mik Contamination W+T, WRQ Climate Siam Climate Surf, W+T, Eco Climate W+T Some questions addressed by: QP: Wave 21, WRQ CCES: Record Record Wave 21 WRQ 3 points to discuss 'WRQ' maps: CH  climate Natural analogues Lakes: integrated models coupling: climate, physics, water quality & biology 3 points to discuss 'WRQ' maps: CH  climate Natural analogues Lakes: integrated models coupling: climate, physics, water quality & biology

20. Vertical “space-for-time” or “space-for-space” analogue Using altitudinal shifts as a proxy for climate warming Choose ~4-5 lakes covering an altitudinal gradient, e.g. Hagelseewli 2339 m a.s.l. / 19 m / 25x10 3 m 2 Seebergsee 1831 m a.s.l. / 15 m / 58x10 3 m 2 Hinterburgseeli 1514 m a.s.l. / 11 m / 45x10 3 m 2 (Schwarzsee 1046 m a.s.l. / 10 m / 455x10 3 m 2 ) Burgseewli 613 m a.s.l. / 19 m / 53x10 3 m 2

21. Impact of climate change on water quality Lakes - Impacts of increased water temperatures in the epilimnion - Cyanobacterial blooms (potentially toxic) - Impacts of a longer stratification period and a shorter period of circulation on oxygen and nutrient concentrations - Impacts of shifts in the timing of physical and biological events - match/mismatch Rivers - Impacts of increased water temperatures on fish habitat - Impacts of a reduction in residual water flow on biota - Impacts of an increased proportion of waste water during dry periods - Cooling problems for large industrial complexes Groundwater - Impacts of a sinking groundwater table on geogenic contamination (e.g., summer of 2003) - Increase in nutrient concentrations (e.g. nitrate) - Changing redox conditions due to higher temperatures - “WRQ maps” for climate change in Switzerland

22. International cooperation For example, cooperating internationally in deploying high-resolution ‘clever’ monitoring involvement on a global scale, e.g. within the expanding international network GLEON...

23. The Global Lake Ecological Observatory Network (GLEON) A grassroots network of –ecologists, engineers, information technology experts –institutions and programs –instruments –data Linked by a common cyberinfrastructure With a goal of understanding lake dynamics at local, regional, continental, and global scales Yuan Yang Lake, Taiwan ; photo by Matt Van de Bogert gleon.org