Illustration by Eric Lobbecke. Source: The Australian

The controversy has two main aspects: is the alarming rise in sea level projected by CSIRO reliable? And is moving people from near-shore sites the correct response?

The CSIRO projection is extreme, but before explaining why, I would note that the world’s main source of alarmism is the Intergovernmental Panel on Climate Change. This is not really a scientific body but one that adjusts data and subjects it to mathematical modelling before passing its “projections” on to politicians.

The CSIRO and Bureau of Meteorology, then further adjust data and produce models with even more extreme scenarios.

In The Weekend Australian on November 7, 2009, the director of the National Tidal Centre of the BOM, Bill Mitchell, reported an Australian average sea-level rise of 1.7mm a year. This is a reasonable level accepted by most sea-level watchers outside the IPCC and CSIRO and gives a sea-level rise of about 15cm by 2100. He said the “upper end was 3mm a year”, which gives a 27cm rise by 2100.

At 8.30am on November 18, 2009, ABC Radio National had a program on sea-level changes. National Sea Change Taskforce executive director Alan Stokes said: “The IPCC estimate of rise to 2100 was up to 80cm.” No new data was provided to explain the leap and, in fact, the worst estimate by IPCC in its last report was 59cm.

Note that the IPCC estimates have been falling with each report. In its second assessment report the high-end projection of sea-level rise to 2100 was 92cm, in the third assessment report 88cm, and the fourth 59cm. It is good for the reader to look at sea-level measurements. You can see the sea-level data for the US and a few other countries at http://tidesandcurrents.noaa.gov/sltrends/sltrends.shtml. Most stations show a rise of sea level of about 2mm a year, but note the considerable variations even within a single state, though these are no cause for alarm.

The CSIRO uses figures far in excess of even the IPCC, which until now were the greatest alarmists. In its 2012 report, State of the Climate, the CSIRO says that since 1993 sea levels have risen up to 10mm a year in the north and west. That means that somewhere has had a 19cm-rise in sea level since 1993. Where is this place? The European satellite says that sea levels have been constant for the past eight years.

How does the CSIRO arrive at its figures? Not from new data but by modelling. Models depend on what is put into them. For example a 2009 report, The Effect of Climate Change on Extreme Sea Levels in Port Phillip Bay, by the CSIRO for the Victorian government’s Future Coasts Program, based its model on temperature projections to 2100 of up to 6.4C. That compares with the most extreme, fuel-intensive scenario of the IPCC and implies unbelievable CO2 concentration levels in 2100 of about 1550 parts per million.

Using all known fossil fuel reserves would achieve only half this and continuing the current rate of increase in concentration levels would result in only 550ppm by 2100. The result is a CSIRO prediction of sea-level rise for Port Phillip Bay by 2100 of 82cm and, with the help of the BOM, a further increase due to wind to 98m. That is well above even the top level projected by the latest IPCC report. This example is from Victoria but sea levels must have roughly the same rises and falls all over the world. So the whole world should be alarmed. Indeed, the IPCC and CSIRO try to alarm the world with stories of the drowning of low islands, such as Tuvalu. But detailed mapping has shown that Tuvalu, and many other coral islands, have actually grown during the past 20 years.

The Netherlands is particularly vulnerable to any large rise of sea levels. It is also a leader in coastal science and engineering, and the Dutch are not alarmed. In the December 11, 2008, issue of NRC/Handelsblad (Rotterdam’s counterpart to The Australian) Wilco Hazeleger, a senior scientist in the global climate research group at the Royal Netherlands Meteorological Institute, wrote: “In the past century the sea level has risen 20cm. There is no evidence for accelerated sea-level rise. It is my opinion that there is no need for drastic measures. Fortunately, the time rate of climate change is slow compared to the lifespan of the defence structures along our coast. There is enough time for adaptation.”

This brings us to the second part of the debate. We should adapt to changes in the shoreline, as do the Dutch. We should reject draconian rules to save folk from a remote and dubious peril. If Tim Flannery is allowed to take his chance living on his Hawkesbury property near sea level, Port Macquarie’s retirees should be permitted to do so too. They should not be evicted to “save” them from a dire fate they will never see.

Cliff Ollier is a geologist, geomorphologist, emeritus professor at the University of Western Australia.