This thesis is focused on determining the rate at which the climate of western North America (WNA) has changed in recent history, and looks at the impact that projected future climatic changes will have on a large glaciated watershed in the Canadian Rocky Mountains. The rate of change over WNA is quantified for 485 climate stations for the period 1950-2005 using indicators developed by the World Meteorological Organization (WMO). Results of the analysis show statistically significant historical trends across the study area. To gauge the effect of climate change on glaciers, a mass balance model was developed and integrated with the University of Lethbridge GENESYS hydrometeorological model. GCM future climate scenarios were used to model change in the Upper North Saskatchewan River Basin through 2100. Results forecast dramatic declines (> 80%) in total glacier area, ice volume, and streamflow contribution by 2100. / ix, 137 leaves ; 29 cm