Sea level rise is the direct result of warming temperatures that trigger increased melting of glaciers and ice caps, as well as the thermal expansion of warming oceans . Glacial coverage in BC has declined since 1985, and the volume of glacial ice declined by an average rate of 21.9 km3 from 1985-2000 . In the coastal mountain area of BC, which includes the MaPP region, glacier area decreased by approximately 6.4% from 1985-2000 . Sea levels are also affected by ocean and weather patterns such as wind, currents, and salinity, and also by subsidence and uplift of the adjacent land mass due to geological processes. Changes in sea level threatens coastal systems through coastal erosion, seawater inundation, contamination of freshwater systems, and can affect food crops grown in low lying areas.
Global mean sea levels increased 10-20 cm during the 20th century, and have been increasing by 3.2 mm/year since 1993 [32,36]. In BC, the average sea level between 1910-2014 has risen along most of the coast, at a rate of 13.3 cm/century at Prince Rupert, 6.6 cm/century at Victoria, and 3.7cm/century at Vancouver . Sea levels at Prince Rupert and Victoria continue to increase, while off the west coast of Vancouver Island tectonic uplift (isostatic rebound from the weight of ice age glaciers) offsets sea level rise such that water levels appear to be declining (removing this uplift would result in a sea level increase of 13.5 cm per century) [10,11].