1Managed by UT-Battelle for the Department of Energy Overview_kpt_0730 Current Fresh Water “Mass Balance”  Water Demand –Resident Population (2003): 150 thousand –Visitors: 1 million per year  Similar yearly demand as about 20 thousand resident  Assuming ~2 weeks average stay per visitor  Water Supply –80% drinking water from ground water –North: 180 wells, 35 Mgal/d  Nearly all wells in North  Primarily limestone aquifer –South: Surface runoff, 9.9 Mgal/d  Surface water runoff over weathered volcanic rock  Occurs locally only after intense rain (high permeability)  “Supply Adequate to Meet Current Needs” (2003 Estimates) –Supply ~ 45 Mgal/d –Demand (proportional to population) ~ 170 thousand –Provides an estimate of average “consumption rate” Source: U.S. Geological Survey (USGS)

2Managed by UT-Battelle for the Department of Energy Overview_kpt_0730 Change in Climate Variables  Temperature –Current: Mean–26 o C; High–30 o C; Low–24 o C –Warming Rate: < 2 degree Celsius per 20 years –Projected: 2010–26 o C; 2015–27 o C; 2030–29 o C  Rainfall –Current Annual Mean: 96 in (2.4 m) / yr –Current Annual Range: in / yr –Current: 70% in Jul-Dec; 12% from Typhoons –Mean Change till 2030: Marginal (<0.1m); Uncertain –Change in Typhoons: Marginal; Uncertain Source: U.S. Global Change Research Program: The Pacific Assessment Source: U.S. Geological Survey (USGS)

3Managed by UT-Battelle for the Department of Energy Overview_kpt_0730 Projected Fresh Water “Mass Balance”  Water Demand –Population 2010: 180K (200K)Water: ~ 53 Mgal/d –Population 2015: 225K (245K)Water: ~ 65 Mgal/d –Population 2030: 250K (270K)Water: ~ 72 Mgal/d  Water Supply –Wells: Current = 35 Mgal/d  The current yield is about 50% of sustainable yield  Sustainable yield: 70 Mgal/d –Surface runoff: Current = 9.9 Mgal/d  Limited projected change under climate change  Occurs locally only after intense rain (high permeability)  Potential Shortfalls: None till 2030 –Total sustainable supply: 79.9 Mgal/d –Estimated demand in 2030: 72 Mgal/d Source: Western Pacific Institute of Guam

4Managed by UT-Battelle for the Department of Energy Overview_kpt_0730 Conclusions  Population change dominates climate change in water supply-demand equation (at least till 2030)  Now till 2030: No anticipated freshwater shortfall; 2030 is about “break-even”  Beyond 2030: Surge in population could cause water scarcity; Climate change impacts still secondary  Beyond 2030: The warming rate could cause slight increase in demand beyond 2050  Large uncertainties for climate change impacts on typhoons; Some uncertainty for non-typhoon rainfall  Change in temperature appears too small for impacts on energy usage  Change in rainfall appears small enough not to impact operations in US DOD facilities

5Managed by UT-Battelle for the Department of Energy Overview_kpt_0730 Recommendations / Guidance  Climate change is not a major concern for freshwater, especially in the next few decades  Population growth may need to be carefully monitored to ensure sustainable freshwater through 2030  Beyond 2030, new ways to generate freshwater may be required  Climate change effects on freshwater may be felt more towards the latter half of the century  Climate change may exacerbate potential water scarcity caused by population

6Managed by UT-Battelle for the Department of Energy Overview_kpt_0730 Related studies Conclusion agree with related studies  Morel, A. and B. Morel (2006): From Global Warming to Water Scarcity: What Are the Most Urgent Environmental Problems of the Region. Report of the Discussion Group on Environmental Security, NATO Security through Science Series,  Vorosmarty, C.J., Green, P., Salisbury, J., and R.B. Lammers (2000): Global Water Resources: Vulnerability from Climate Change and Population Growth. Science, 289 (5477):