Peyto Glacier is one of the best studied glaciers in North America and one of 30 global ‘benchmark’ glaciers.
One of the most important measurements of a glacier’s health is mass balance. Glacier mass balance is the sum of mass gained by a glacier (primarily through snowfall) and mass lost (primarily through surface melt). If more mass is gained than lost the glacier has positive mass balance and grows, if less mass is gained than lost the glacier has negative mass balance and shrinks.
The plot below shows the cumulative net mass balance (in meters of snow water equivalent) of Peyto Glacier from 1966 to 2009. When this plot descends it is showing years of successive negative mass balance. The few jumps back up show years where Peyto Glacier had positive mass balance. The trend of ongoing negative mass balance is clear.
The data in the graph above includes date from Natural Resources of Canada and the Geological Survey of Canada (1966 – 2007) and from the World Glacier Monitoring Service (2008-2009).
For further information on global glacier mass balance (including Peyto Glacier) a good place to start is this publication by the United Nations Environment Programme and World Glacier Monitoring Service:
Demuth, M. N., Skerka, J., and Bertollo, S., 2009, Glacier mass balance observations for Peyto Glacier, Alberta, Canada (updated to 2007), Spatially referenced data set contribution to the National Glacier-Climate Observing System, State and Evolution of Canada’s Glaciers, http://pathways.geosemantica.net/WSHome.aspx?ws=NGP_SECG&locale=en-CA, Geological Survey of Canada, Her Majesty the Queen in Right of Canada, 2009.
Zemp, M., Nussbaumer, S. U., Garnter-Roer, I., Hoelzle, M., Paul, F., and Haeberli, W. (eds.), 2011, WGMS Glacier Mass Balance Bulletin: Bulletin No. 11 (2008-2009), ICSU (WDS), IUGG (IACS), UNEP, UNESCO, WMO.