One hundred and seventy thousand is approximate number of glaciers left in the world. (Vaughn et al., 2013). Glaciers that have been around for hundreds of thousands of years are melting to extinction. Since 2007, there is very high confidence that essentially all of the glaciers worldwide have continued to shrink proven by the time series of measured changes in glacier length, area, volume and mass. (Vaughn et al., 2013). From glaciers that meet the sea to glaciers high in mountains on the equator, rising atmospheric temperatures are having lasting impacts on the massive, slow moving hunks of ice. (Vaughn et al., 2013).
British Columbia and Alaska are two regions of the world that are home thousands of glaciers of varying types. (Vaughn et al., 2013). Land terminating glaciers in Southern British Columbia to tidewater glaciers in Inside Passage, Southcentral and Southwest regions of Alaska are thinning and receding causing a slew of literal “downstream” effects. This region, the Pacific Northwest region of North America, contains some of the least anthropogenically impacted ecosystems in the world, yet they are reaping the devastating effects of a warming climate and a warming climate. (Romero-Lankao et al., 2014). “In British Columbia (BC) alone, for example, glaciers cover 3% of the landmass (30,000 km2) and serve as frozen freshwater reservoirs that supplement snowmelt and rainfall runoff during summer and early autumn. Glaciers represent a substantial source of renewable energy, contribute to the sustainability of ecosystems, and bolster the tourism economy in both the United States and Canada.” (Moore et al., 2009). Alaska is home to 23,112 glaciers covering approximately 89,267km2 of land. Western Canada and the US have 15,073 glaciers covering 14,503.5km2. (Vaughn et al., 2013). The mass rates of change are rather frightening for those two regions. In Alaska, –570 ± 200kg m2 is being lost whereas –930 ± 230kg m2 is being lost in Western Canada and the US. In this paper, the types of glacial retreat in the study regions will be explained and elaborated upon and the impacts evaluated. The downstream impacts on ecosystems and how they affect mountain and skiing communities will be determined.
Glacial Retreat & Terminus:
The terminus of glaciers is a natural process. Glaciers slowly move downhill due to the natural forces of gravity. (Moore et al., 2009). Higher elevation glaciers that can typically be found in southern/warmer climates are, in most cases, land terminating glaciers meaning that a drainage stream is found at the end of a glacier. (United States Geological Service, 2013). Lake terminating glaciers occur when the tongue of the glacier is met by a lake that has formed in a basin as a result of glacial erosion. (Moyer et al., 2016). The glacier calves into the lake, often in dramatic fashion. This creates a positive feedback thus accelerating the rate of glacial melt due due the increased glacial flow rate. (Moyer et al., 2016). The appropriate term for when the ocean meets the tongue of the glacier is a tidewater glacier. These also calve into the water, often on a larger scale than lake terminating with a slightly more significant positive feedback system due to the nature of the oceans, also accelerating the rate of ice flow. (USGS, 2013), (Moyer et al., 2016). It is difficult to quantify which type of glacier melts at faster rates as each glacier is unique in terms of mass, density, velocity, age, rates of accumulation and ablation in combination other factors.
Exposure and Vulnerability
Warming trends = longer melt seasons
Seasonally earlier peak melt
Short term increased streamflow
Long term decreased streamflow
Change in stream dynamics
Sea level rise