Case 2:Policy implications

of sea level rise

Measuring tides

Modern device similar. also measures wind speed and direction, water current speed and direction, air and water temperature, and barometric pressure.

Sea level data

Monthly observations 1959-2008, 55 sites, 6 in WA

Global mean sea level

Each point in the global mean sea level (GMSL) time series plots is the area-weighted mean of all of the sea surface height anomalies measured by the altimeter of the TOPEX A/B satellite in a single, 10-day satellite track repeat cycle (time for the satellite to begin repeating the same ground track).

Difference between gauges and satellite

Land motion• glacial rebound (millenial scale)• tectonic activity (decadal scale)

Altimeter drift• orbital drift• instrument drift

Where do the climate model values come from?

Change insea level height

Cumulative change in temperature(slow response)

Change intemperature(quick response)

Downscaling

Find a statistical relationship between global sea level change and local sea level change

Apply this relationship to global sea levels estimated from projected temperatures

Uncertainties?

Projected sea level rise in Puget Sound

Mote et al. (2008)

Scenario 2050 SLR 2100 SLR

Very low 8 cm 16 cm

Medium 15 cm 34 cm

Very high 55 cm 128 cm

Consequences for Olympia

Some thoughts

Not only mean sea level that matters

Even in the very low scenario, a combination of heavy rain, high tide, and storm surge can cause major damage

Not everyone is convinced that the threat is real

...but

Dec 17, 2012, 5.4 m tide

The task

• Develop a set of policy options regarding sea level rise for the city of Olympia

• Produce supporting projections of sea level rise with estimates of uncertainty

• Present the results and some background material on a set of linked web pages aimed at the general public