20-09-11 Climate Change in the tropical Andes and its impacts on glaciers: observations and projections Rocio Urrutia & Ambarish Karmalkar (Univ. Oxford, UK) Mathias Vuille Department of Atmospheric and Environmental Sciences University at Albany, State University of New York Irmgard Juen & Georg Kaser (Univ. Innsbruck, A) Douglas Hardy & Ray Bradley (Univ. of Massachusetts, USA) Bernard Francou & Bolivar Caceres (IRD, INAMHI, Quito, ECU) Waldo Lavado (SENAMHI, Lima, PE) Rene Garreaud (Univ. de Chile, Santiago, Chile) Dana McGlone & Eric Franquist (Univ. at Albany, SUNY, USA) Part I: Current observations Observations of glacier retreat Glacier Espejo, Pico Bolivar (5002 m) Venezuela 1910 Photos courtesy Eduardo Carillo 1988 < 2 km2 of ice left in Venezuela 2008 Jahn [1931]; Schubert [1992, 1999] 1
2009 Photo B. Francou 2
The retreat of 10 tropical glaciers in Ecuador, Peru and Bolivia Vuille et al., Earth Sci. Rev., [2008] Glacier mass and energy balance Chacaltaya, Bolivia Antizana, Ecuador Vuille et al., Earth Sci. Rev., [2008] Changes in cloud cover (net radiation is main energy flux measured on glacier surface) Changes in humidity (partitioning of available energy into melt and sublimation) Rate and timing of snowfall determines albedo Sensible heat flux is not main component of glacier energy balance, however integrates all above aspects through temperature 3
Sensitivity of glacier mass balance to temperature and precipitation in the Cordillera Blanca, Peru Temperature Precipitation Gray circles: p<0.05 Black circles: p<0.01 Vuille et al., Global Planet Change, [2008] 20th century temperature trends in the tropical Andes Near-surface temperature increase of 0.68 C since 1939 (~0.1 C decade -1 ) Vuille & Bradley, Geophys. Res. Lett., [2000] Vuille et al., Climatic Change, [2003] Vuille et al., Earth Sci. Rev., [2008] 4
Rising freezing line in the tropical Andes Daily maximum air temperature (hourly averages) on Quelccaya Ice Cap, Peru summit (5680 m) Bradley et al., Geophys. Res. Lett., [2009] The impact of glacier retreat on runoff Monthly hydrologic mass balance at glacier Yanamarey (Cordillera Blanca, Peru) Bury et al., Climatic Change [2011] 5
Part II: Future Projections Option 1: Consider free tropospheric temperature change 9000 60 40 20 0-20 m 8000 7000 6000 5000 4000 3000 2000 Mountain peaks 7 6.5 6 5.5 5 C 4.5 4 3.5 3 2.5 1000 2-40 -160-140 -120-100 -80-60 -40-20 0 20 40 60 South North Latitude Projected change in temperature (1990-99) to (2090-99) along the American Cordillera, from Alaska to Chile (mean of 8 GCMs (IPCC AR4) scenario A2) Bradley et al., Science, [2006] Option 2: Use of high-resolution regional climate models (RCM s) PRECIS RCM Had RM3, nested in HadCM3 50 km horizontal resolution Tropical South America (10º N-27º S; 86º W-44º W) Ctrl (1961-90), ERA (1957-2001) A2 (2070-2100): 15 billion people, 850 ppm of CO 2 by 2100 B2 (2070-2100): 10.4 billion people, 550 ppm of CO 2 by 2100 6
21 st century GHG emissions in the context of the past million years 2100 High emission scenario 2100 Low emission scenario 2011: 392 ppm Annual mean temperature change for B2 and A2 (2070-2100) minus Ctrl (1961-90) B2 A2 Urrutia & Vuille, J. Geophys. Res., [2009] 7
Change in near-surface Andean temperature distribution in 2 emission scenarios CTRL (1961-90) B2 (2071-2100) A2 (2071-2100) Annual mean Temperature along western Andean slopes Urrutia & Vuille, J. Geophys. Res., [2009] PRECIS Model-Domain Karmalkar et al., GRL, [2008] Urrutia & Vuille, JGR, [2009] PRECIS (HadRCM3) Garreaud et al., Univ. de Chile, [2009] 8
The impact of glacier retreat on runoff Relevance of this process: - most important in regions such as Peru, where rivers drain into seasonally arid lowlands Kaser et al., PNAS, [2010] - less relevant in inner tropics where paramos can take on regulating function and where precipitation is less seasonally biased Buytaert et al., Earth Sci. Rev. [2006] Kaser et al., J. Hydrol., [2003] - similar processes at play in extratropical Andes, but seasonal snow cover of higher relevance (snow cover is not a significant seasonal storage term in the tropics) Wagnon et al., J. Geophys. Res., [2009] Simulated changes in runoff (relative to 1961-90) in different catchments of the Cordillera Blanca ParÛn Llanganuco Chancos delta Q [%] delta Q [%] 0 20-40 -20 0 20 40-40 -20 40 wet dry 40.9% 31.0% delta Q [%] 10 12 1 2 3 4 5 6 7 8 9 10 12 1 2 3 4 5 6 7 8 9 month (Oct - Sept) month (Oct - Sept) Quillcay Pachacoto wet dry 17.4% -40-20 0 20 40 delta Q [%] -40-20 0 20 40 wet dry wet dry 9.7% delta Q [%] -40-20 0 20 40 wet 24.1% 10 12 1 2 3 4 5 6 7 8 9 month (Oct - Sept) b1-2050 a2-2050 b1-2080 a2-2080 dry Runoff change in % in 2050 and 2080 for B1 and A2 scenarios 10 12 1 2 3 4 5 6 7 8 9 month (Oct - Sept) 10 12 1 2 3 4 5 6 7 8 9 month (Oct - Sept) Juen, PhD Univ. Innsbruck, [2006]; Vuille et al., Earth Sci. Rev., [2008] 9
Adaptations in water use and management Technological Adaptation - creation of water reservoirs - exploit new water resources - conservation measures - construction of water treatment plants Scientific strategies - improve monitoring network - better assimilation of new data systems (GIS, remote sensing) - advance regional climate projections (downscaling) Policy instruments - regional training and capacity building - improve collaboration between scientists, stakeholders, water managers - scientific results need to be accessible and translated into language that is understandable by non-scientists Goal must be to reduce the vulnerability and increase the resilience of water users Towards a sustainable development Adaptations for future generations are needed Photo: M. Vuille Jones and Mearns, [2004] Goal must be to reduce the vulnerability and increase the resilience of water users 10
Temperature change as a function of elevation Temperature Change (A2 Ctrl) along western Andean slopes Urrutia & Vuille, J. Geophys. Res., [2009] 11