Urban Heat Islands

The Hon. T.T. NGO (15:36): I rise today to speak on the urban heat island effect. It is well documented that during extreme hot weather the heat in Australia's urban areas intensifies and the locations that this intensified heat occurs in are known as urban heat islands. Although we may have experienced a cooler January this year, Australia is one of the world's hottest continents. In fact, on 4 January 2020, the hottest place on Earth was Penrith in Western Sydney. Its official temperature was 48.9º, keeping in mind that, according to the Bureau of Meteorology, above 35º is defined as hot and above 40º is extreme.

Dr Fiona Foo, a Sydney cardiologist, says, 'Already heat waves are silent killers, causing more deaths than other natural disasters combined.' Given that around 86 per cent of Australia's population is urbanised, the shape and planning of our cities will have a huge impact on addressing urban heat islands in Australia.

According to a report prepared by the consultancy firm Edge South Australia, many of the heat islands in Adelaide are home to our most vulnerable. The report mentioned that most of the heat islands identified in Adelaide's north-eastern suburb of Campbelltown coincided with areas of high vulnerability.

Some of the developer-led housing estates cram large houses onto small sites or build two or even three where only one previously existed. Although we have tree planting strategies in place, the trees that are planted are decades away from providing decent shade. Consequently, hard surfaces, dark rooftops, heat absorbent materials, traffic and lack of shade all contribute to making our urban temperatures 10º or 15º higher than our surrounding regional areas.

Research tells us that the most successful strategy we can use to tackle the urban heat island is to plant the right trees in the right places. Many streets in Adelaide showcase beautiful trees that were planted decades ago, showing us the value of the shade they provide today. We know all trees provide shade, hold groundwater, nurture soil and suck up carbon. The deciduous species provide us with summer shade and winter sunlight. The preferences around whether we should be planting native trees versus the deciduous European species should be viewed in terms of the location and functionality of the trees.

The Melbourne City Council was recently calling for tenders to manage and maintain its city trees. The council describes Melbourne's urban forest as one of its most valuable assets because of its crucial role in helping remove pollution and in keeping Melbourne streets cooler during hot weather. In fact, according to arboriculturist Mr Ryan Roche, Melbourne has the largest concentration of mature elm trees in the world.

We know trees need light to grow, and cities need better airflow during hot weather; however, dense clusters of high-rise buildings block both. This fact highlights the importance of city environments, including more buildings of varied height and shape.

The member for Badcoe, Ms Jayne Stinson, in the other place is Chair of the parliamentary inquiry currently responding to Adelaide's shrinking tree canopy. The parliamentary inquiry has looked at data that shows that most of Adelaide's residential suburbs have significantly less tree coverage than they did 10 years ago.

As we move towards a future that must address the urban heat island, at a time when the construction of houses, apartments and infrastructure is rising, the importance of increasing our tree canopy and repurposing our city buildings to encourage better airflow and light will be essential.