Flood Risk and Vulnerability Analysis Project - Atlantic Climate ...

3.4.4 Sea Level Rise
Figure 3-20. Predicted Annual Tropical Cyclone Frequency for the North
Atlantic Ocean (based on Effect of Climate Variability and Change in
Hurricane Activity in the North Atlantic Report, 2011)
Sea level monitoring is an important activity as the data are used directly at the planning stage
as inputs to the development of flood risk maps and at the operational level as part of flood
forecasting and emergency measures response. This is particularly relevant for a province such
as Newfoundland and Labrador with a preponderance of coastal municipalities.
Sea level is affected by short-term and longer-term causes. Short-term changes may include
tides, seasonal fluctuations due to precipitation and evaporation, and temporary sea level
changes from intense storms which result in reduced atmospheric pressure and storm surge or
wind setup; both conditions that can effectively raise the sea level at the shoreline.
For the longer term, sea level is an ocean indicator for climate change. Sea level in the
province has been observed to be rising relative to benchmarks and wharf deck elevations. The
rate of global mean sea level rise is presently estimated at about 3 mm/year, yet another
confirmation that global warming is already underway. There are regional differences. For the
North Atlantic, a comparable rate of about 2.5 mm/year is estimated. This is illustrated in Figure
3-21 which is based on satellite altimetry data 17 . These rates may increase with continued
melting of the polar ice caps and warming of the oceans.
17 satellites, such as TOPEX/Poseidon, use radar altimetry to measure ocean surface topography: radio waves are
sent to the ocean surface and timing their return gives very accurate (within a few centimeters) measurement of sea
level.
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