Hydrology and Earth System Sciences www.hydrol-earth-syst-sci.net 1027-5606 1607-7938 14 7 2010 10.5194/hess-14-1247-2010 http://www.hydrol-earth-syst-sci.net/14/1247/2010/ http://www.hydrol-earth-syst-sci.net/14/1247/2010/hess-14-1247-2010.html http://www.hydrol-earth-syst-sci.net/14/1247/2010/hess-14-1247-2010.pdf 1247 1258 2010-07-15 Uncertainties in climate change projections and regional downscaling in the tropical Andes: implications for water resources management W. Buytaert w.buytaert@imperial.ac.uk M. Vuille A. Dewulf R. Urrutia A. Karmalkar R. Célleri Imperial College London, Civil and Environmental Engineering, London, UK Univ. at Albany, State Univ. of New York, Dept. of Atmospheric and Environmental Sciences, Albany, USA Wageningen Univ., Public Administration and Policy Group, Wageningen, The Netherlands Univ. Austral de Chile, Laboratorio de dendrocronología, Valdivia, Chile Univ. of Massachusetts Amherst, Climate System Research Center, Amherst, USA Univ. de Cuenca, Centro para el Análisis de Sistemas Naturales, Cuenca, Ecuador Climate change is expected to have a large impact on water resources worldwide. A major problem in assessing the potential impact of a changing climate on these resources is the difference in spatial scale between available climate change projections and water resources management. Regional climate models (RCMs) are often used for the spatial disaggregation of the outputs of global circulation models. However, RCMs are time-intensive to run and typically only a small number of model runs is available for a certain region of interest. This paper investigates the value of the improved representation of local climate processes by a regional climate model for water resources management in the tropical Andes of Ecuador. This region has a complex hydrology and its water resources are under pressure. Compared to the IPCC AR4 model ensemble, the regional climate model PRECIS does indeed capture local gradients better than global models, but locally the model is prone to large discrepancies between observed and modelled precipitation. It is concluded that a further increase in resolution is necessary to represent local gradients properly. Furthermore, to assess the uncertainty in downscaling, an ensemble of regional climate models should be implemented. Finally, translating the climate variables to streamflow using a hydrological model constitutes a smaller but not negligible source of uncertainty. Allen, M R. and Ingram, W J.: Constraints on future changes in climate and the hydrologic cycle, Nature, 419, 224–232, 2002. Allen, R G., Pereira, L S., Raes, D., and Smith, M.: Crop evapotranspiration. Guidelines for computing crop water requirements, FAO Irrigation and Drainage Paper 56, FAO, Rome, 1998. Bates, B C., Kundzewicz, Z W., Wu, S., and Palutikof, J.: Climate Change and Water. Technical Paper of the Intergovernmental Panel on Climate Change, IPCC Secretariat, Geneva, 2008. Beniston, M.: Climate change in mountain regions: a review of possible impacts, Climatic Change, 59, 5–31, 2003. Beven, K. and Binley, A.: The Future of Distributed Models: Model Calibration and Uncertainty Prediction, Hydrol. Process., 6, 279–298, 1992. Beven, K J.: Rainfall-runoff modelling. The primer, John Wiley & Sons, Chichester, 2001. Bradley, R S., Vuille, M., Diaz, H F., and Vergara, W.: Threats to water supplies in the tropical Andes, Science, 312, 1755–1756, 2006. Bradley, R S., Keimig, F T., Diaz, H F., and Hardy, D R.: Recent changes in freezing level heights in the tropics with implications for the deglacierization of high mountain regions, Geophys. Res. Lett., 36, L17701, \doi10.1029/2009GL037712, 2009. Brugnach, M., Dewulf, A. R. P J., Pahl-Wostl, C., and Taillieu, T.: Toward a relational concept of uncertainty: about knowing too little, knowing too differently, and accepting not to know, Ecol. Soc., 13, 30, 2008. Buytaert, W., De Bièvre, B., Wyseure, G., and Deckers, J.: The use of the linear reservoir concept to quantify the impact of changes in land use on the hydrology of catchments in the Andes, Hydrol. Earth Syst. Sci., 8, 108–114, doi:10.5194/hess-8-108-2004, 2004. Buytaert, W., Célleri, R., De Bièvre, B., Hofstede, R., Cisneros, F., Wyseure, G., and Deckers, J.: Human impact on the hydrology of the Andean páramos, Earth-Sci. Rev., 79, 53–72, 2006a. Buytaert, W., Célleri, R., Willems, P., De Bièvre, B., and Wyseure, G.: Spatial and temporal rainfall variability in mountainous areas: A case study from the south Ecuadorian Andes, J. Hydrol., 329, 413–421, 2006b. Buytaert, W., Célleri, R., and Timbe, L.: Predicting climate change impacts on water resources in the tropical Andes: the effects of GCM uncertainty, Geophys. Res. Lett., 36, L07406, doi:10.1029/2008GL037048, 2009. Célleri, R. and Feyen, J.: The Hydrology of Tropical Andean Ecosystems: Importance, Knowledge Status, and Perspectives, Mt. Res. Dev., 29, 350–355, 2009. Célleri, R., Willems, P., Buytaert, W., and Feyen, J.: Space-time variability of rainfall in the Paute River basin of South Ecuador, Hydrol. Process., 21, 3316–3327, 2007. Chapman, T G.: Modelling stream recession flows, Environ. Modell. Softw., 18, 683–692, 2003. Croke, B. and Jakeman, A.: A catchment moisture deficit module for the IHACRES rainfall-runoff model, Environ. Modell. Softw., 19, 1–5, 2004. da Rocha, R P., Morales, C A., Cuadra, S V., and Ambrizzi, T.: Precipitation diurnal cycle and summer climatology assessment over South America: An evaluation of Regional Climate Model version 3 simulations, J. Geophys. Res., 114, D10108, doi:10.1029/2008JD010212, 2009. Dercon, G., Govers, G., Poesen, J., Sánchez, H., Rombaut, K., Vandenbroeck, E., Loaiza, G., and Deckers, J.: Animal-powered tillage erosion assessment in the southern Andes region of Ecuador, Geomorphology, 87, 4–15, 2006. Dessai, S. and Hulme, M.: Assessing the robustness of adaptation decisions to climate change uncertainties: A case study on water resources management in the East of England, Global Environ. Chang., 17, 59–72, 2007. Dessai, S., Hulme, M., Lempert, R., and Pielke Jr, R.: Climate prediction: a limit to adaptation?, in: Adapting to Climate Change: Thresholds, Values, Governance, edited by: Adger, W N., Lorenzoni, I., and O'Brien, K., 64–78, Cambridge University Press, Cambridge, 2009. Diaz, H F., Duncan, J. K. E C., and Bradley, R S.: Variability of freezing levels, melting season indicators and snow cover for selected high elevation and continental regions in the last 50 years, Climatic Change, 59, 33–52, 2003. Fowler, H J., Blenkinsop, S., and Tebaldi, C.: Linking climate change modelling to impacts studies: recent advances in downscaling techniques for hydrological modelling, Int. J. Climatol., 27, 1547–1578, 2007. Francou, B., Vuille, M., Favier, V., and Cáceres, B.: New evidence for an ENSO impact on low-latitude glaciers: Antizana 15, Andes of Ecuador, 0°28'S, J. Geophys. Res., 109, D18106, \doi10.1029/2003JD004484, 2004. Garreaud, R. and Falvey, M.: The coastal winds off western subtropical South America in future climate scenarios, Int. J. Climatol., 29, 543–554, \doi10.1002/joc.1716, 2009. Haylock, M R., Peterson, T C., Alves, L M., Ambrizzi, T., Anunciacao, M T., Baez, J., Barros, V R., Berlato, M A., Bidegain, M., Coronel, G., Corradi, V., Garcia, V J., Grimm, A M., Karoly, D., Marengo, J A., Marino, M B., Moncunilland, D F., Nechet, D., Quintana, J., Rebello, E., Rusticucci, M., Santos, J L., Trebejo, I., and Vincent, L A.: Trends in total and extreme South American rainfall in 1960–2000 and links with sea surface temperature, J. Climate, 19, 1490–1512, 2006. Heltberg, R., Siegel, P B., and Jorgensen, S L.: Addressing human vulnerability to climate change: Toward a `no-regrets' approach, Global Environ.l Chang., 19, 89–99, 2009. Insel, N., Poulsen, C J., and Ehlers, T A.: Influence of the Andes mountains on South American moisture transport, convection and precipitation, Clim. Dynam., in press, \doi10.1007/s00382-009-0637-1, 2010. IPCC: Climate Change 2001: Impacts, Adaptation and Vulnerability, Cambridge University Press, Cambridge, 2001. IPCC: Climate Change 2007 – Impacts, Adaptation and Vulnerability, Cambridge University Press, Cambridge, 2007. Jones, R G., Noguer, M., Hassell, D., Hudson, D., Wilson, S., Jenkins, G., and Mitchell, J.: Generating high resolution climate change scenarios using PRECIS, Met Office Hadley Centre, Exeter, 2004. Karmalkar, A V., Bradley, R S., and Diaz, H F.: Climate change scenario for Costa Rican montane forests, Geophys. Res. Lett., 35, L11702, doi:10.1029/2008GL033940, 2008. Kingston, D G., Todd, M C., Taylor, R G., Thompson, J R., and Arnell, N W.: Uncertainty in the estimation of potential evapotranspiration under climate change, Geophys. Res. Lett., 36, L20403, doi:10.1029/2009GL040267, 2009. Maraun, D., Wetterhall, F., Ireson, A M., Chandler, R E., Kendon, E J., Widmann, M., Brienen, S., Rust, H W., Sauter, T., Themeßl, M., Venema, V. K C., Chun, K P., Goodess, C M., Jones, R G., Onof, C., Vrac, M., and Thiele-Eich, I.: Precipitation downscaling under climate change. Recent developments to bridge the gap between dynamical models and the end user, Rev. Geophys., in press, \doi10.1029/2009RG000314, 2010. Marengo, J A., Jones, R., Alves, L M., and Valverde, M C.: Future change of temperature and precipitation extremes in South America as derived from the PRECIS regional climate modeling system, Int. J. Climatol., 29, 2241–2255, 2009. New, M., Hulme, M., and Jones, P.: Representing twentieth-century space-time climate variability. Part I: Development of a 1961-90 mean monthly terrestrial climatology, J. Climate, 12, 829–856, 1999. New, M., Lister, D., Hulme, M., and Makin, I.: A high-resolution data set of surface climate over global land areas, Clim. Res., 21, 1–25, 2000. Oudin, L., Michel, C., and Anctil, F.: Which potential evapotranspiration input for a lumped rainfall-runoff model? Part 1, Can rainfall-runoff models effectively handle detailed potential evapotranspiration inputs?, J. Hydrology, 303, 275–289, 2005. Pahl-Wostl, C.: Transitions towards adaptive management of water facing climate and global change, Water Resour. Manag., 21, 49–62, 2007. Soares, W R. and Marengo, J A.: Assesments of moisture fluxes east of the Andes in South America in a global warming scenario, Int. J. Climatol., 29, 1395–1414, 2009. Stainforth, D A., Allen, M R., Tredger, E R., and Smith, L A.: Confidence, uncertainty and decision-support relevance in climate predictions, Philos. T. R. Soc. A, 365, 2145–2161, 2007a. Stainforth, D A., Downing, T E., Washington, R., Lopez, A., and New, M.: Issues in the interpretation of climate model ensembles to inform decisions, Philos. T. R. Soc. A, 365, 2163–2177, 2007b. Still, C J., Foster, P N., and Schneider, S H.: Simulating the effects of climate change on tropical montane cloud forests, Nature, 398, 608–610, 1999. Timbe, E.: Disgregacion temporal de datos diarios de precipitacion en microcuencas de páramo, Master's thesis, Universidad de Cuenca, 2004. Urrutia, R. and Vuille, M.: Climate change projections for the tropical Andes using a regional climate model: Temperature and precipitation simulations for the end of the 21st century, J. Geophys. Res., 114, D02108, \doi10.1029/2008JD011021, 2009. Vera, C., Silvestri, G., Liebmann, B., and Gonzalez, P.: Climate change scenarios for seasonal precipitation in South America from IPCC-AR4 models, Geophys. Res. Lett., 33, L13707, \doi10.1029/2006GL025759, 2006. Viviroli, D., Archer, D. R., Buytaert, W., Fowler, H. J., Greenwood, G. B., Hamlet, A. F., Huang, Y., Koboltschnig, G., Litaor, M. I., López-Moreno, J. I., Lorentz, S., Schädler, B., Schwaiger, K., Vuille, M., and Woods, R.: Climate change and mountain water resources: overview and recommendations for research, management and politics, Hydrol. Earth Syst. Sci. Discuss., 7, 2829–2895, doi:10.5194/hessd-7-2829-2010, 2010. Vuille, M., Bradley, R S., and Keimig, F.: Climate variability in the Andes of Ecuador and its relation to tropical Pacific and Atlantic sea surface temperature anomalies, J. Climate, 13, 2520–2535, 2000. Vuille, M., Bradley, R S., Werner, M., and Keimig, F.: 20th century climate change in the tropical Andes: observations and model results, Climatic Change, 59, 75–99, 2003. Vuille, M., Francou, B., Wagnon, P., Juen, I., Kaser, G., Mark, B G., and Bradley, R S.: Climate change and tropical Andean glaciers: Past, present and future, Earth-Sci. Rev., 89, 79–96, \doi10.1016/j.earscirev.2008.04.002, 2008. World Meteorological Organisation: Guide to Hydrological practices, WMO Publication 168, WMO, Switzerland, 1995.