Commentary and Analysis on the Whitehead & Associates 2014 NSW Sea-Level Report
SummaryIn July 2014, Whitehead & Associates Environmental Consultants, in consultation with Coastal Environment and with funding from the NSW Government, produced a report for Eurobodalla Shire Council and Shoalhaven City Council titled “South Coast
In July 2014, Whitehead & Associates Environmental Consultants, in consultation with Coastal Environment and with funding from the NSW Government, produced a report for Eurobodalla Shire Council and Shoalhaven City Council titled “South Coast Regional Sea Level Rise Policy and Planning Framework, Exhibition Draft.” The conclusion of the following commentary and analysis is that this report does not provide reliable guidance to the complicated issues of measuring, forecasting, and responding to sea-level rise.
The image below presents the unmistakeable pattern of wide variations in rates of tectonic uplift (points above the red zero baseline) and subsidence (points below) in different locations around the world at particular times. In such circumstances, no effective coastal management plan can rest upon speculative computer projections regarding an idealised future global sea-level, such as those provided by the United Nations’ Intergovernmental Panel on Climate Change (IPCC).
Coastal management must instead rest upon accurate knowledge of local geological, meteorological and oceanographical conditions, including, amongst other things, changes in local relative sea level.
For the central and southern New South Wales (NSW) coast of Australia, this requires basing management policies on the range of long-term rates of sea-level rise of 0.63-0.94 mm/yr that have been measured at the nearby Sydney (Fort Denison) tidal gauge.
The implied 6.3-9.4 cm of rise in the next hundred years is similar to the rise which occurred during the preceding hundred years. This did not require, nor receive, any policy formulation over and above the application of historic 20th century coastal planning regulations.
Elevation v. age plotted for individual intertidal shoreline deposits from around the world over the last 10,000 years (Holocene) (Newman, 1986).