INNOVATION September-October 2012

f ea t u r e s

Preparing for Sea Level Rise in British Columbia: Science, Policy and Practice

Below: Storm surge water levels in Victoria Harbour on November 24, 2011. Photos taken as part of the King Tides Photo Initiative, a public event asking people to photograph shorelines during high tides and imagine the same shorelines with one meter of sea level rise.

Tina Neale Jesal Shah PEng PE

Steve Young, City of Victoria.

Introduction Sea level rise is “an inevitable consequence of global warming” 1 and preparing for it will require careful planning and collaboration among governments, the private sector and individuals. It will also require developing new methods and tools for coastal flood protection. The BC Government has been working with partners on a range of activities to learn more about how sea level rise will affect the BC coast and incorporate that learning into government roles and responsibilities. This article provides a brief overview of work to date related to incorporating sea level rise considerations into provincial flood hazard management activities. What Are We Preparing For? Global average sea level has risen about 20 cm since the industrial revolution. Scientists have estimated that sea level will continue to rise, reaching 47 to 190 cm above 1990 levels by the year 2100. 2 On the BC coast, the amount of sea level rise that will occur locally will depend on global sea level rise and local effects such as land uplift or subsidence. If global average sea level rises by 1 m, locations along the BC coast will see increases between about 0.5 and 1.2 m, depending on the rate of vertical land movement. Local relative sea level rise projections for some BC communities, assuming 1 m global sea level rise, are shown in table 1. In addition to increased average ocean water levels, sea level rise will result in: • More extreme high water levels during storm surges that coincide with high tides; • Changes in erosion and sedimentation patterns;

Relative Sea Level Rise (m) GLOBAL SEA LEVEL RISE = 1 m

location

Price Rupert

0.95

Queen Charlotte City

0.79

bella bella

0.78

port hardy

0.76

campbell river

0.62

tofino

0.75

vancouver

0.89

richmond

1.20

1 Copenhagen Diagnosis 2009. 2 IPCC, “Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation.A Special Report of Working Groups I and II of the Intergovernmental Panel on Climate Change,” 2012. Table 1. Relative sea level rise for year 2100, above 1990 levels, at specific BC tide gauge or GPS station locations. Assumes 1 m global sea level rise and includes vertical land velocity. Source: Richard Thomson, Brian Bornhold, Stephane Mazzotti, Addendum to “An examination of the factors affecting relative and absolute sea level in coastal British Columbia,” 2008.

• Migration and loss of coastal habitats; • Possible impacts on coastal aquifers.

2 6

S e p t e m b e r /Oc to b e r 2 012

i n n o v a t i o n