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TitleRelative and absolute sea level rise in western Canada and northwestern United States from a combined tide gauge-GPS analysis
AuthorMazzotti, S; Jones, C; Thomson, R E
SourceJournal of Geophysical Research vol. 113, C11019, 2008, 19 pages, (Open Access)
Alt SeriesEarth Sciences Sector, Contribution Series 20070616
Mediapaper; on-line; digital
File formatpdf
ProvinceWestern offshore region; British Columbia
AreaWashington; Oregon; California; Alaska; Canada; United States of America
Lat/Long WENS-136.0000 -120.0000 58.0000 40.0000
Subjectsenvironmental geology; marine geology; Nature and Environment; sea level changes; sea level fluctuations; coastal environment; environmental analysis; environmental studies; environmental impacts; global positioning system; climate change
Illustrationslocation maps; tables; plots
ProgramEnhancing resilience in a changing climate
Released2008 11 21
AbstractEmpirical studies and climate models suggest large variations of absolute sea level (ASL) changes between oceanic basins. Such potential variations raise concern on the applicability of global mean ASL predictions to specific regions and on estimates of relative sea level (RSL) hazards. We address this issue for the western Canada and northwestern United States coastline by estimating the 20th century ASL rate using a combination of 34 colocated tide gauge and Global Positioning System (GPS) stations. The tide gauge data are quality controlled and corrected for spatially and temporally correlated sea level transients in order to derive robust RSL trends and standard errors. Reference frame and other GPS-specific issues are considered as part of the error budget in absolute GPS vertical velocities. Our combined tide gauge-GPS analysis, aligned to the International Terrestrial Reference Frame 2000, indicates a northeast Pacific ASL rise of 1.8 ± 0.2 mm/a through the 20th century, which is similar to accepted rates for the global eustatic mean. For the period 1993 - 2003, we find a regional ASL rate of -4.4 ± 0.5 mm/a consistent with satellite altimetry. On the basis of the Intergovernment Panel on Climate Change Assessment Report 4 mean scenario and our assessment of coastal motions from GPS and tide gauge data, we derive a map of predicted 21st century RSL rise in western Canada and the northwestern United States. Variations in coastal uplift strongly affect spatial RSL patterns. Subsidence of southern Puget Sound may significantly increase RSL rise in the Seattle-Tacoma metropolitan area. Conversely, tectonic uplift along parts of the outer west coast may reduce future RSL rise by up to 50 - 100%.