Likely sealevel rise not as bad as you think

DUNEDIN is very fortunate in that it has a long data set of sea levels available at both Dunedin itself and at Port Chalmers. The data is freely available for anyone to obtain online.

For this reason, I find the article in the ODT (1.2.19) to be a case of scaremongering.

The range of sealevel rise for Dunedin predicted by Nasa is from a low of 30cm to a high of 1.3m, while Niwa gives a much tighter range of a low of 40cm to a high of 1m.

The scaremongering part comes from the part of the story where it reports that ‘‘Even under a 1m sea level rise scenario, $446 million worth of infrastructure would be left exposed’’.

This is the very upper limit of the Niwa scenario and well into the upper range of the Nasa estimate, but the use of the words ‘‘Even under . . .’’ suggests that a 1m rise is at the lower end of probabilities.

The likely range is actually much lower than either the Nasa or Niwa report and is quite easy to calculate. The mean sea level (MSL) trend at Dunedin is +1.32 mm/year with a 95% confidence interval of +/0.19 mm/year, based on monthly mean sea level data from 1900 to 2016, and has a rate of change of 0.00887mm per year.

From this, it is very easy to calculate the likely sea level increase by 2100. Assuming CO2 continues to increase at the current rate then we can expect to see an increase in sea level in Dunedin of between 13cm and 16cm.

Malcolm Taylor

Alexandra

K92 locomotive

IT was really amazing to see the locomotive K92 back in full glory and running at Mandeville. Hats off to all involved.

I was wondering how the Fiordland vintage club found the locomotive’s location. I would like to add this to the trip. P. Quinn

Oamaru

[K92 was placed in the Oreti River, near Lumsden, for erosion control. She was retrieved by the Fiordland Vintage Machinery Club in 1985 and later restored. — Ed.]