Blacktown is experiencing a rise in annual temperatures above what would be expected from global warming. Photo: Adam HollingworthWestern Sydney is not waiting for Greg Hunt’s trees.
This week,the acting Cities Minister announced a federal government pledgeto increase tree coverage in Australian cities each decade to 2050, an effort to “green” and “cool” the city.
Amid the decade-by-decade goals to develop urban canopies, the commitment will see the government “look at building rooftops with green cover”.
But in western Sydney, where the heat is worst felt, councils aren’t waiting for the Turnbull government’s plan. In fact, many have already got their own strategies well under way.
In western Sydney, where the sea breeze stops around Strathfield, development is rapidly increasing and lost tree cover is not always replanted.
The region is the perfect setting for the urban heat island effect, where localised warming occurs due to dark-coloured and paved surfaces, buildings and the emission of heat from human activities.
It is a reality that has spurred the Western Sydney Regional Organisation of Councils into action.
Over the past 40 years, western Sydney weather stations have recorded a rise in annual temperatures above what would be expected through global warming.
The effect is strongest in Blacktown but also apparent in Richmond, Camden, Liverpool and Parramatta.
“The problem is not the iconic city centres where there is money to invest in urban renewal, but in the suburbs in western Sydney,” said Dr Brent Jacobs, research director for the Institute of Sustainable Futures and the University of Technology, Sydney.
“We have a legacy of past development that didn’t account for urban heat islands and pressure for new, affordable housing developments to accommodate population growth.”
Over the next 20 years, the population of western Sydney will grow by almost 1 million people, while 180,000 homes are set to be built in “priority growth areas” over the next 15 years.
The Office of Environment and Heritage estimates that development of these areas will increase urban heat in the west, with 10 extra “extremely hot” days by 2030.
Dr Jacobs said the problem is that “we keep repeating the same mistakes”.
“We keep producing the same types of residential development and we have big legacy effects from where we’ve had residential development in the past and we haven’t really revegetated after development has gone in.”
In an urban heat island scenario, paved ground surfaces transport more solar heat downwards than soil. This heat is then released overnight.
Both Parramatta and Penrith councils have conducted aerial heat mapping of their local area in order to identify extreme heat pockets.
Further west, Blacktown City Council’s urban heat project, The Cool Streets, is assessing how street trees can mitigate heat build-up in residential areas.
“We have designed streetscapes that lower temperatures by combining deciduous and evergreen trees to provide different shade cover throughout the year,” said the acting mayor of Blacktown City Council, Jacqueline Donaldson.
In Penrith, the city council’s sustainability team is exploring ways to combat the urban heat island effect, working with Dr Jacobs’ team at UTS and the CSIRO.
“We completed a ‘Cooling the City Strategy’, with more than 50 actions in the areas of policy and planning, community engagement, green infrastructure and water-sensitive urban design that will help cool the city,” said Jenny Guice, senior sustainability planner.
The strategy will see greater planning for water features and schools, the use of lighter-coloured building materials and up to 4000 new trees planted in Leonay and Emu Plains.
Every new tree will go towards achieving the202020 Vision, a national plan to increase the amount of green space in urban areas by 20 per cent, by 2020.
Last year, a report by the Institute of Sustainable Futures mapped tree canopy coverage across Australia.
Among the 139 local government areas assessed, it found 47 per cent of Australia was grass-bare ground, 39 per cent tree canopy cover, 8 per cent hard surface and 6 per cent shrub.
Dr Jacobs said a lot of interest was generated by the report, prompting contact from various councils around Australia.
“A lot of those councils have started to work with local landscape designers and academics,” he said, but added, it would be a long time before technological innovation found its way through to everyday use.
“We’ve got new materials, like porous concrete which people could use for car parks, but these haven’t found their way into standard practice in the building industry yet.”
The story Beat the heat: Western Sydney tackles the urban heat island effect originally appeared on The Sydney Morning Herald.