Change in Sea Level in B.C. (1910-2014)
Sea level changes when the overall volume of water in the ocean increases or decreases and when land moves vertically from geological processes. Thermal expansion—when the atmosphere warms, sea water warms and expands in volume—is a major influence on past changes in sea level and is expected to make the greatest contribution to a rising sea level over the next century. This indicator measures changes in the average level of the sea relative to the adjacent land based on records from 1910 to 2014 at four tide gauges along the British Columbia coast.
- Average sea level has risen along most of the B.C. coast over the past century. Average sea level rose at a rate of 13.3 centimetres per century at Prince Rupert, 6.6 centimetres per century at Victoria and 3.7 centimetres per century at Vancouver. In contrast, average sea level fell at Tofino at the rate of 12.4 centimetres per century.
- Sea level trends identified for coastal B.C. reflect the combined impacts of climate change and vertical land movements. The coast of B.C. is still rising from a geological process called post-glacial rebound—the rising of land due to past thinning and retreat of the massive ice sheet that once covered much of the province. In addition, the shifting of the tectonic plates generates vertical land motion in coastal B.C. causing parts of Vancouver Island to rise.
- Variation in sea level change between the four B.C. sites is largely explained by different amounts of vertical land movement. Land along the southwest coast of Vancouver Island is rising at about 25 centimetres per century, while vertical land motion of Prince Rupert is negligable, thus explaining the approximately 25 centimetres difference in sea-level change between Tofino and Prince Rupert.
Observed Change in Sea Level in B.C. (1910-2014)
Average sea level has risen along most of the British Columbia coast over the past century.
Interpreting the Trend Information:
- This assessment was conducted by the Pacific Climate Impacts Consortium using data from Fisheries and Oceans Canada.
- Relative sea level data is collected at tide gauges at numerous locations along the coast of Canada. Trends were calculated at four long-term stations on the B.C. coast that all have data as early as 1910. Large gaps exist for some records in the 1920s and 1930s, however the selected trend estimator accomodates such gaps.
- 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.
More About Sea Level
- Sea level also changes when the overall volume of water in the ocean increases or decreases. As glaciers, ice caps and ice sheets lose mass from melting, water previously stored on land as ice and snow is added to the ocean. This additional water is expected to contribute substantially to a rise in global sea level over the next century.
- Climate models project a further rise in global mean sea level of 26 to 98 centimetres by 2100. The rate and magnitude of this rise in sea level will not be uniform over the globe. It will vary from one basin to another, reflecting variations in the amount of ocean warming and the way in which ocean currents redistribute heat and mass.
The methods used to develop this indicator and more about change in sea level 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 size of B.C. glaciers and sea surface temperature 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 January 2017