Catherine StewartSydney’s new suburbs will be most affected global warming

Sydney weather

By 2050, Sydney’s new outer suburbs will be much worse affected by global warming than the city, due to a lack of green spaces, tree cover and open water say researchers at the ARC Centre of Excellence for Climate System Science.

Overnight temperatures remain higher in new housing subdivisions which are mostly on the western and south western fringes of the city. This is due to heat island effects, where heat absorbing surfaces hold and then reradiate heat at night, as well as prevent the cooling effects of surface evaporation. These higher overnight temperatures will also increase resident’s reliance on air conditioning for overnight cooling during summer.

Newer subdivisions

15 year old Sydney subdivision

Dr Paul Osmond from UNSW Built Environment says that changing planning guidelines to place greater emphasis on street trees, green open space and incorporating lakes into urban design could help reduce this heat island effect.

While you might expect that older parts of the city that are more built-up would have a higher temperature increase, climate change modelling predicts that the new outer suburbs will have a temperature rise of 1.1 to 3.7 degrees C, compared to city changes of only 1.1 to 2.5 degrees C.

older suburb

70 year old Sydney suburb

I think the conversation needs to be about more than just street trees per se. My observations are that:

1. many newer suburbs have indigenous street trees which are either barely more than shrubs (like bottlebrush) or not great shaders. I love my eucs and indigenous plants but the truth is that the exotic trees found through older suburbs provide much denser shade over roads and residential hard surfaces.

2. houses in newer subdivisions have almost no back or front yards and therefore nowhere to plant a large shrub, let alone a proper shade tree. They also tend to be populated by newer migrants to Australia who do not come from cultures where trees are either valued or planted. When confronted by the choice of planting and maintaining a shade tree in their tiny yard or using air conditioning, of course they’ll choose an aircon every time.

130 year old Sydney suburb

130 year old Sydney suburb

 

Interestingly, very old suburbs with detached terrace-style housing have quite a lot of tree cover when you look at Google maps, so I think it’s as much to do with house block shapes, house design and residents’ choices as it is total size.

 

 

 

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Catherine Stewart

About Catherine Stewart

Award-winning garden journalist, blogger and photographer; writer for garden magazines and co-author of 'Waterwise Gardening'; landscape designer turned landscape design judge and critic; compulsive networker and lover of generally putting fingers in lots of pies. Particularly mud pies. Original creator of GardenDrum. South Coast NSW.

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