The latest scientific observations of rising sea levels suggest that it is not enough. A report by the United Nations (2009) published in time for the climate change talks in Copenhagen at the end of the year, suggests a sea level rise of a metre over the next century, with 5 or 10 times that rise in the following centuries.  The reason for this more recently published concern is that scientific observations since the turn of the millennium have indicated an average sea level rise of about 3mm per year compared with an average of about 1.7mm for the 20^th century (i.e. a rate that is nearly double those of last century). 

Scientists attribute the rising sea levels to thermal expansion of the oceans (water expands as it heats up), the melting of glaciers and icecaps in regions such as the Himalayas, the high Arctic and Patagonia, melting of the ice sheets of Antarctica and Greenland, and additions to the ocean from land, as water is pumped from ancient aquifers for surface use, and then released to rivers and streams.

The Ministry for the Environment advise is too conservative in my view because:

·         Coastal areas tend to be sites of high capital investment (e.g. expensive holiday homes, marinas, tourism establishments);

·         Construction of infrastructure such as roads, jetties and port facilities,  has long-term consequences for subsequent  land use (i.e. when roads are built, houses and businesses tend to follow);

·         Peak oil and the rising cost of energy alternatives to fossil fuels will mean that the cost of redesigning and reconstructing coastal infrastructure and coastal developments is likely to be much greater in future.

·         Many coastal ecosystems are vulnerable to damage or destruction as a consequence of sea level rise (for example, the Miranda shell banks, which support  thousands of shore birds, tidal flats and estuaries which provide habitat for shellfish and juvenile fish).

·         Coastal areas are likely to be subject to multiple stresses and hazards, including storms, tsunamis, high winds (particularly on the west coast) and flooding of low-lying areas.

In my view, a precautionary approach would be to plan for sea level rises of a metre or more.  I would expect provisions to include shoreline setbacks for building and roads to a height of at least a metre, and the extent of coastal access strips and riparian margins to be determined on the basis of a height above sea level rather than a distance from mean high water or the edge of a river.