Change in Snowpack in B.C. (1950-2014)
Snow accumulation and its characteristics are the result of air temperature, precipitation, storm frequency, wind and the amount of moisture in the air. Changes in these and other climate properties can therefore affect snowpack. This indicator measures changes in snow depth and changes in snow water content—also called snow water equivalent, the amount of water that is contained in the snowpack. Results are provided for each of the nine terrestrial ecoprovinces in British Columbia.
- Snow depth and the water content of snow both significantly decreased in three of B.C.'s ecoprovinces. Snow depth and snow water content decreased at a rate of 11 and 7 percent per decade in the Southern Interior, 10 and 5 percent per decade in the Central Interior, and 7 and 5 percent per decade in the Southern Interior Mountains. In addition, snow depth decreased by 6 percent per decade in the Georgia Depression with no observed change in snow water content.
- Trends in snow depth and snow water content are not uniform across B.C. No significant trends were detected in snow depth or water content of snow in the the Northern Boreal Mountains, Taiga Plains, Boreal Plains, Sub-Boreal Interior and Coast and Mountain ecoprovinces.
- Snow density overall has increased in four ecoprovinces. Together, snow depth and snow water content provide information about snow density. Snow depth decreased at a faster rate than the water content of snow in three ecoprovinces (Southern Interior, Central Interior and Southern Interior Mountains), and snow depth decreased in the Georgia Depression while the water content of snow showed no change. In general, density increases when snow water content increases for the same volume of snow, or as depth decreases while snow water content remains constant.
- Winter warming is the most likely cause of increasing snow density. As winter temperatures warm, more winter precipitation is likely to fall as heavy "wet" snow. Rain or sleet may compact snow already on the ground, and warmer air temperatures can cause snow already on the ground to melt onto itself.
Why Is Snowpack Important?
Snow acts as a temporary storage system for winter precipitation.
When snow melts the water becomes available to fill reservoirs and rivers, recharge groundwater aquifers and replenish soil moisture.
Changes in snowpack affect the amount of water that is stored over the winter and released in the spring and summer.
Observed Change in Snow Depth in B.C. (1950-2014)
Snow depth has decreased in 4 ecoprovinces during the last century.
Observed Change in Snow Water Equivalent in B.C. (1950-2014)
Snow water content has decreased in 3 ecoprovinces during the last century.
Interpreting the Trend Information:
- This assessment was conducted by the Pacific Climate Impacts Consortium using data from the Province of British Columbia.
- Trends are based on data collected at provincial snow survey monitoring stations in Spring (April 1) between 1950 and 2014. Most stations are located between 1,000 and 2,000 metres above sea level.
- Results were found to be significant at the 95 percent level. This means that there is a less than 5 percent probability that the results arose randomly.
- Where the data fail to reveal a trend that is statistically significant at the 95 percent level, data are annotated with an "NS" to indicate that the trend is not significant.
More About Changes in Snowpack
- The Intergovernmental Panel on Climate Change (IPCC) has concluded that there is a highly significant correlation between increases in surface temperatures and decreases in the extent of snow and ice in the Northern Hemisphere.
- The amount of precipitation that falls as snow will continue to vary from year to year in response to natural climate cycles. Climate models project, however, that as the Earth continues to warm, the extent of snow cover in the Northern Hemisphere will continue to decrease during the 21st century.
The methods used to develop this indicator and more about change in snowpack and other climate indicators are available in Indicators of Climate Change for British Columbia (2015-16 Update) (PDF, 4.5MB). The R code for creating the graphs presented on this page is available on GitHub.
References and Other Useful Links
- Learn about change in air temperature, precipitation and size of glaciers in B.C.
- Learn about snow survey data in B.C.
- Learn more about climate science from the Pacific Institute for Climate Solutions online courses: Climate Insights 101
- B.C. Environment: Climate Change
- Pacific Climate Impacts Consortium
- Pacific Climate Impacts Consortium Data Portal
*By accessing these datasets, you agree to the licence associated with each file, as indicated in parentheses below.
Updated February 2017