Rolleston rushfires a nasty surprise for Canterbury fire fighters


Kia Ora

Just when we were sympathising with our Australian neighbours and their bushfire woes, caused by a so-called dome of heat – really a broad mass of very hot (up to 49 degrees Celsius)air slowly moving across continental Australia – out of nowhere today pops a grass fire near Rolleston (sorry New Zealand viewers only). Within minutes, it has quickly gotten established and moves on neighbouring properties. Before very long, four properties are ablaze and New Zealand has just had a brutal dose of what Tasmanian’s, Victorian’s, South Australian’s and people in New South Wales have been experiencing all week.

There is no doubt that in Australia if one lives in rural or urban areas, with eucalyptus trees in predominantly dry areas, come summer and the passage of continental heat coming out of the interior, conditions exist for bush fires. In 1967, 1983, 1994, 1999, 2003 and 2009 bush fires have claimed large numbers of lives and property. The 2009 Victorian bush fires destroyed hundreds of homes and killed over 200 people, decimating entire towns, wiping out huge numbers of stock and wild life. Video coverage showed tornadoes of fire moving
faster than a man could run tearing up a hill; gale winds blowing embers well ahead of the fire front forcing people to flee their houses and eucalyptus trees exploding as their oil ignited.

New Zealand has not been subjected to the same extremes, largely because of its geography and maritime climate where the continental heat extremes are absent. The summers however, in Otago and Canterbury, Hawkes Bay and Marlborough can be very hot with temperatures occasionally exceeding 40 degrees, but usually stopping in the mid-30 degree Celsius range. The drying effect of the northwesterly wind, known elsewhere around the world as the Fohn wind or the Chinook wind can quickly dry out the ground and sustained days of the westerly airstream crossing the Southern Alps, whilst dropping rain on the West Coast can push the fire risk to extreme quite quickly.

New Zealanders are undoubtedly horrified by the fire conditions that can arise and the danger posed, but until they have to fight an out of control bush fire themselves, it is a different story. The summer period often sees, mainly from lightning strikes or burn offs ignoring conditions and common sense, scrub fires break out in New Zealand. The ones that break out in the Otago or Canterbury high country usually require helicopters and water bombing aircraft to bring them under control. Some of them can incinerate thousands of hectares easily before conditions permit a semblance of control to be gained. But occasionally the unsettling thought that someone has delibrately lit a fire to satisfy their pyromaniac fantasies has to be entertained. At this time there is no thought that the Rolleston fire was the work of fire bugs, and it could have been something really innocent like a person using welding or other equipment requiring or likely to generate sparks or a naked flame.

As bush fires do not occur very frequently here, they cannot be blamed on climate or other environmental change. However that is not to say that a drier, more arid environment would not be conducive to bush fires. Nor is it to say that heat extremes could not create on a lesser scale, the sorts of conditions that occurred in Australia on Tuesday, and which continue to threaten vast swathes of the country. It would be useful for New Zealand meteorology if geographers were to study models of air masses over New Zealand specifically to look for possible indicators of extreme heat or heatwaves in anticipation of possible fire issues as a natural hazard in the future.

And as I wind up this article, it has come to my attention another fire has started near West Melton.

Take Care,

Rob

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