Saturday, February 11, 2017

A sizzling Saturday - extreme heat, breezeways and the meaning of catastrophic fire danger

It's been a sizzling Saturday, with temperatures exceeding 40C (104F) in over 50 suburbs, towns and villages across NSW. Animals have been suffering as well as people. The koala photo comes courtesy of the ABC"s twitter feed.

The highest temperature in the state on Saturday was Ivanhoe at 47.6C (117.68F); still below the highest record for anywhere in NSW recorded in 1939 at 49.7C (121.46F). A number of centres exceeded their previous record highs including.

  • Penrith (Western Sydney) reached 46.9C (116.42F), beating its previous record of 46.5C (115.7F)
  • Forbes (Western NSW) recorded 45.5C (113.9F), with its previous record 44C (111.2F)
  • Williamtown (Hunter Valley) also reached 45.5C after a previous high of 44.7C (112.46).

In addition to the formal temperature readings, there is the felt temperature, how the temperature feels taking humidity into account. Here some parts of Western Sydney reached 51C (123.8F). Then is there is the ground temperature which can exceed the recorded temperature by a considerable margin where the earth or pavement is exposed to direct sunlight. I have no idea here, but one council at least sprayed water to prevent the tar on the main road bubbling.

Saturday came following a period of sustained hot weather in South Eastern Australia as a consequence of a block of hot air forcible suspended over part of the continent by other systems with temperatures in many places at or over 40C.

In the heat, I became curious about the comparison between these heats and global record temperatures, Looking at wikipedia, the temperatures are very high by global standards if still below the maximums set elsewhere.

While I generally accept the arguments about climate change, including the role human related emissions are playing in the process, my experience with previous heatwaves and the response to them makes me very cautious about attributing particular climatic events to climate change. It has lead to some very silly policy responses, especially in NSW. What we can certainly say is that this type of heat forces behavioral responses including cancellation of sporting events, a rush to buy fans and air-conditioners and to get some place cool. In turn, this has placed some pressure on the electricity supply system.

I live in a house without air-conditioning or, indeed, any fans. I'm also working from home at the moment, so the heat is especially trying. For that reason, my only practical response lies in managing the house to create breezeways and minimise sun impacts.

I was surprised to discover that the word breezeways is apparently US in origin, dates to the twentieth century and refers to a porch or roofed passageway open on the sides, for connecting two buildings, as a house and a garage.  I first came across it in looking at Australian colonial architecture where the phrase was used more broadly to describe an element of house construction, especially in hotter areas.

A lot of thought went into house design and there was actually a fair bit of variety. This a shot of Lanyon Homestead  in the ACT. The large verandahs shielded the walls and provided sheltered outdoor living space. Doors opened onto verandahs allowing the interior of the house to be ventilated. The twentieth century moved away from this approach, especially in modern houses whose design increasingly came to be dependent on the availability of air-conditioning.  

My place is older and it is possible to manage it to some degree to reduce impact of heat and create breezeways to some degree. It's still been bloody hot!

Towards the end of the day, the NSW Rural Fire Service started warning of catastrophic or code red conditions in some parts of NSW. Code red conditions stretch from the Hunter Valley up the Western Slopes.

I have written about the introduction of  the catastrophic or code red system before (here, here). In 2013 when the then Premier declared code red in parts of the State on the grounds that it was the most catastrophic fire danger the state had ever faced, the advice was:
“If you live in bushland or an isolated area where there is a catastrophic fire danger rating your only option is to leave early. You could move to a built up area, away from bushland, such as the centre of a town.’’
Now the advice appears to be something along the same lines with an added urban twist including chilling out in an air-conditioned shopping centre or at a swimming pool. If you look at the scale of the area covered by the catastrophic and extreme fire danger warnings, I just don't understand how things might work. How do you select the centre, how might these be defended, do you just give up areas?

There may be answers to all this, but I don't know,  


2 tanners said...

It has been reasonably hot in Canberra too. I miss those old verandahs! We have a deck, but the roof isn't tin, it's translucent plastic which doesn't help much in this weather. In a piece of nanny-statism the result of which I quite like, the ACT has forced homeowners to show how well their houses are passively heated/cooled when they come to sell. Owners of 'Tuscan' style houses have to admit that you need heating and cooling year round - i.e. you might like the look but you'll pay for it in cash or, in the case of a blackout, in discomfort. Mind you, my west facing fibro house complete with tin roof rates 0.5 on the 6 point scale so that'll come back to bite me one day!

Just to get it off the table, the disaster scenario for climate change is a world-wide average 4 degree rise. Not a blistering day in Forbes, however uncomfortable that may be. Back to the current weather...

The heat and high winds have led to brittle gums (can't remember their proper name) snapping off sizeable branches all over our neighbourhood. I tend not to walk in high winds at the moment - some of those branches are a hundredweight or more. And I remember the tar bubbling in the streets of Adelaide as a more-or-less annual event.

Jim Belshaw said...

Morning, 2t. Interesting comment on the houses. By Tuscan,do you mean what we used to call Italian modern as compared to Yugoslav Gothic? Intuitively, I would have assumed tuscan style to be suitable for hot weather. Mind you, having just done a web search and looked at some modern examples, not at all sure of that!

Many gums do shed branches even at the best of times. Totally sympathise re walking around in winds!

2 tanners said...

The Tuscan style came to Canberra about a decade ago. Tile roof (usually black!) with eaves about 6 inches wide, or no eaves at all, just a gutter. At the time I viewed it as yet another way for builders to cut costs. Hate to live in one.

Jim Belshaw said...

I agree with you