Mike Finlayson: Climate change a concern

Reading this now, in relatively fine weather, last week's storms don't seem as much of a threat.

Images of the Hunua Falls raging, New Lynn underwater and Coromandel campers being almost washed away have started to fade in our minds eye and will soon be forgotten.

Only landowners with pasture underwater, damaged access tracks or other storm related damage will still be acutely aware of the power of Mother Nature.

What did the damage was a semi stationary tropical cyclone parked west of us in the Tasman Sea.

Although not a 'monster' cyclone it managed to lash us twice within a few days, sending campers scurrying for higher ground and school kids home early.

Seemed like a week before things were scorchingly hot, literally in fact if you lived in the Port Hills near Christchurch where tussock, trees, farms and houses almost spontaneously combusted after an intense hot dry period.

The link between global temperature rise and atmospheric carbon is rock solid.

From pre industrial levels of 280 parts per million we have recently reached a new high of 400ppm.

Some climate scientists believe we have already passed the 'tipping point' to keep global temperature rise beneath 2 degrees C.

2015/16 have been the two hottest years ever recorded. And the lag between atmospheric carbon and rising temperatures means, even if we stopped using fossils fuels right now, the temperature is going to rise even more.

This means more water vapour in the atmosphere pumping bigger and bigger weather systems.

Kaitaia has been built on a floodplain that drains three major catchments upstream. We have been seriously lucky we have never had a storm of the intensity that hit the Hunuas.

The maximum flow measured to date has never exceeded 150 cubic meters/second.

Modelling indicates that an intense 1 in 100 storm hitting all three catchments simultaneously would cause around 250 cu m/s to surge through our town.

Looking at the flood maps in this scenario is not a pretty picture. All the stop banks have been breached, the town is way past 'knee deep' and some residential areas are metres under water.

The damage would be massive and the threat to life significant. And this is without factoring in the impact that climate change will have on intensifying storm systems.

So, as chairman of the Awanui Drainage Scheme Liaison Committee I am more than a little worried about the future prospects for our town.

It is not a matter of 'if' but 'when' the biggy is going to hit us.

Your Regional Council is currently spending just under $400,000 per year on maintenance and minor improvement.

To make the radical improvements needed to safeguard our town would be in excess of $10 million. And that's a lot of money for a town of just 5000 residents.

I would be very interested in your comments.

Would you accept a rates increase to cover this? How much risk have we got an appetite for ?

Email Mike here: mikef@nrc.govt.nz