The Urban Heat Island Effect

The following is a summary of a position statement by the Australian Institute of Landscape Architects titled, Cooling Cities – The Heat Island Effect.

It is now indisputable that average temperatures are on the increase, giving rise to elevated urban heat island, (UHI) effects. With now more than three quarters of our population living in urban areas, more people are becoming susceptible to health issues that can be directly related to the UHI.

On this 'heat map' of England, London, Liverpool, Manchester etc, are easy to locate!

 Simply put, an urban heat island is a city or other urban area that is significantly warmer than the surrounding areas due to human activities. UHI is caused by the presence of heat absorbing materials – concrete, asphalt, etc, the clearing of green spaces and in cities, the building of skyscrapers resulting heat trapping canyons.  

In 2013, research undertaken by Melbourne City Council determined that the average temperature in the CBD was 4°C higher than the surrounding suburbs. At night, because the heat absorbing materials then release their heat, the difference is as much as 12° higher.

Heat related deaths in Melbourne in 2013 totaled approximately 200. The state road toll for 2013 was 243! UHI effects increase the health risks particularly to the young and the elderly.

A report commissioned by the City of Melbourne concluded that “… the total impact of the UHI effect contributes a cost of approximately $300 million dollars …”

Drouin's tree cover is worth saving.

Among other conclusions, the AILA advocates for

# Greater protection of existing tree cover through increased value assessment of their worth.

# Commitment from all levels of government to annually increase tree canopy cover in urban areas.

# Greater awareness of the value in greening new and existing urban spaces.

Further reading links...

‘Melbourne city centre a death trap as heat-island effect takes its toll’ – The Age Jan17, 2014.

‘Beat the heat: western Sydney tackles the urban heat island effect’ – The Sydney Morning Herald Jan22, 2016.

‘Responding to the Urban Heat Island: A Review of the Potential of Green Infrastructure’ – Victorian Centre for Climate Change AdaptationResearch (1.38MB pdf).