Sea-level trend analysis for coastal management

A proper coastal management requires an accurate estimation of sea level trends locally and globally. It is claimed that the sea levels are rising following an exponential growth since the 1990s, and because of that coastal communities are facing huge challenges. Many local governments throughout Australia, including those on the coast, have responded to the various warnings about changes in climate and increases in sea levels by undertaking detailed climate change risk management exercises. These exercises, which use projections passed on by the relevant state bodies, are expensive, but still a fraction of the cost of the capital works that they recommend. Several councils have complained to an Australian Productivity Commission report on climate change adaptation they do not have the money for the capital works required. It is shown here that the exponential growth claim is not supported by any measurement of enough length and quality when properly analysed. The tide gauge results do not support the exponential growth theory. The projections by the relevant state bodies should therefore be revised by considering the measurements and not the models to compute the future sea level rises for the next 30 years following the same trend experienced over the last 30 years.

► Various natural and human processes affect the sea level and the shoreline.
► Understanding the periodical oscillations is important to evaluate the accelerating trends.
► Australia has non-accelerating sea levels strongly influenced by periodical oscillations.
► Non-linear fittings with periodic functions permit to determine the periodic fluctuations.