Science Centres: Climate

Samoa keeps a wary eye on the sea

Average maximum hourly sea level relative to mean sea level for Apia.

Much of the population of Samoa lives on low lying coastal areas, and is vulnerable to extreme high tides, storm surges, and other coastal hazards.

A Climate Risk Profile (CRP, see reference) prepared for Samoa in 2007 describes a number of present and future climate risks to Samoa, among which are:

• an observed average sea level rise of 5.2 mm/year, and
• an observed average maximum hourly sea level rising ata rate of 8.2 mm/year.

The adjacent figure, taken from the CRP report, shows average maximum hourly values of sea level for Apia, relative to an historical mean sea level.

Exceptionally high sea levels have caused flooding of coastal communities, accelerated coastal erosion, and salt water intrusion into groundwater. Some very high sea levels have been associated with El Niño events. Historical data show that an average hourly sea level height of 1.7 m above mean sea level is estimated to be a 1-in-40 year event. An hourly sea level of 1.8 m above the mean is estimated to occur only about once in 230 years.

The CRP notes the large interannual variability, but also a long-term trend of increasing average sea level. The report estimates that a mean sea level rise of 36 cm is likely by 2050, and that the frequency of high sea level events is likely to increase with climate change.

The cover picture of this publication shows a section of coastal protection work undertaken by the Government of Samoa, designed to protect coastal communities from current and future adverse coastal conditions.

Reference:
Climate Risk Profile for Samoa. Wairarapa J Young, Samoa Meteorological Division, Ministry of Natural Resources and Environment, Samoa. (March 2007).