Council is sticking to these two benchmarks, despite the fact  the government policy has been removed, and is instead relying on expert advice from CSIRO, which invented the benchmarks. 

There is another side to this.  

I have been actively involved with every council workshop and community forum on sea-level rise since the first one at Belmont 16 Footers in April 2013. I do believe sea level is rising, I do believe we need an adaption plan and I have made constructive contributions to that end. But I also believe the council has jumped the gun on the issue, implementing unnecessary non-negotiable controls. 

There are three points in relation to the benchmarks they use to justify these controls.

First, the two benchmarks are derived from two different sources. The 0.4-metre projection in 2050 comes from the outdated 2001 Intergovernmental Panel on Climate Change (IPCC) report. The 0.9-metre projection comes from the current 2007 IPCC report. Without getting too technical, this means there is a significant step change in 2050 when the sea-level rise has to change curves.  I’m not challenging the science itself, but the way it has been presented to the public is definitely not good science.

Second, CSIRO added 10centimetres in 2050 and 14centimetres in 2100 to the global projections and applied them to NSW, and only NSW, based on their own modelling of the impact of the east coast current. It is a linear model, so you can easily extrapolate back to 2000 to deduce that NSW sea level should already be six centimetres higher than all the other states. The Bureau of Meteorology has 31 weather stations in Australia with 25 to 100 years of data. The three in NSW (Newcastle, Fort Denison and  Port Kembla) have been rising at a rate 35per cent lower than the Australian average, and the Australian average is 25per cent lower than the global average. It is hard to imagine how we could already be sixcentimetres higher than the other states and the rest of the world.

And finally, council (CSIRO) has justified using the top-end projections of the range predicted by IPCC because actual measurements of sea level by both satellite and tide gauges around the world fit exactly over the top curve. The problem is that when you check the CSIRO website you find that the satellite trend is twice the tide gauge trend and both are linear, so they cannot fit exactly over each other, let alone a curve and they are both under the curve.

Sea-level rise is a very emotive issue in my suburb. The residents raise the question of validity of the science at every forum. People look out their window and have not noticed any change in lake levels in their lifetimes. In fact, over the past 28 years the lake has  risen seven centimetres at Belmont. Given that the tide varies by 30 to 40centimetres twice daily and the smallest wave exceeds seven centimetres, people can be excused for not noticing. 

‘‘Why don’t you fix the drains first? They are a problem now!’’ the residents say.

Even though council works on our behalf, and councillors/local members are elected by us, they don’t seem to be too interested in us. I’d like to publicly challenge council to tell us: Why do you use one current and one outdated IPCC report as the basis of your sea-level rise benchmarks?

What evidence is there to support a higher projection in NSW compared with the rest of the world and the rest of Australia?

Convince us that Lake Macquarie is trending towards the top end of the CSIRO-modified IPCC projections.

 Frank Mieszala, now retired, was the environment manager at Eraring Power Station and is an active member of the Pelican Area Sustainable Neighbourhood Group