Global Warming to Intensify in Sydney’s Urban Areas

Saturday, July 20th, 2013
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A recent study launched by the Australian Research Council (ARC) Centre of Excellence for Climate System Science maintains that average temperatures in Sydney’s urban areas will increase by as much as 3.7 degrees Celsius by the year 2050.

The study, Temperature Response to Future Urbanization and Climate Change, examines the impact of the expansion of Sydney’s suburbs using a simulated climate scenario that incorporates the projected changes in the urban area of Sydney.

A comparison between areas with projected land use changes and their surroundings was conducted to analyse how urbanization and global warming will affect the local climate. The results revealed that future urbanization will have a huge impact on minimum temperature, while a smaller impact was detected for maximum temperature.

According to the report, the minimum temperature changes will be visible throughout the entire year. However, during winter and spring these differences will be particularly large and the increase could double due to global warming by 2050.

“Interestingly, we found that overnight temperatures increased far more than temperatures during the day,” said Study leader Dr. Daniel Argueso. “This has implications for health problems related to heat stress accumulation and at an economic level where the higher energy consumption needed to power air conditioning overnight may lead to higher power bills.”

The urban expansion in Sydney’s western area is bringing about new development on the city’s fringes, with the area expected to house more than 100,000 residents. New urban areas such as this are expected to experience the largest change in temperature, mostly due to the increased heat capacity of urban structures, urban heat island effects, and reduced evaporation in the city environment.

Western Sydney Suburbs

Western Sydney Suburbs

“Current research shows that along with other strategies green spaces, street trees  and bodies of water can have a marked effect on reducing urban heat island effect,” said Dr. Paul Osmond, a Green Star Accredited Professional involved in the research. “Not only do these help keep suburbs cooler, there is also a knock-on effect where these places gain social advantages through additional amenities and recreational areas.”

Urban structures are able to store and eventually release more heat than the green/land areas, meaning that the more buildings a city has, the higher the local temperatures will be. The urban heat island effect that causes nighttime temperatures to exceed those recorded during the day is maximized when the heat stored by buildings throughout the day is released at night.

The researchers’ most important recommendation is that both urban planners and architects must make an effort to ensure that projects for future suburbs built in Sydney in the coming years incorporate green spaces, trees and bodies of water.

Five years ago, a report presented by not-for-profit environmental organisation Greening Australia suggested 10 ways to reduce Western Sydney’s urban heat island effect that can be applied to future projects. Many of them can also be incorporated into existing urban areas to help reduce temperatures.

Sydney Royal Botanic Gardens

Sydney Royal Botanic Gardens

The techniques suggested to reduce the urban heat island effect are:

  • The preservation of all large patches of vegetation
  • The inclusion of street trees to shade pavements and roads
  • Light coloured roofing to increase reflectivity
  • Increased vegetation cover across the landscape
  • The maintenance of green open spaces
  • Landscaping with vegetation to reduce solar radiation reaching buildings and thereby reducing heat storage
  • Water sensitive urban design that promotes water retention on properties and natural water features including wetlands, streams and water courses
  • Sustainable street design measures
  • A reduction in energy use and the promotion of energy efficiency in urban design
  • Promoting mass transport to reduce private vehicle usage, which is a large contributor of anthropogenic heating in urban areas

While both studies focused on western Sydney, they provide valuable concepts for regional climate assessments that apply to cities across Australia and around the world.

“We need to develop a complete profile of temperature changes for different cities taking into account their various urban expansion prospects and locations. With this information, we can provide an invaluable tool to help with the future development of Australian cities and the environment many of us live in,” Argueso said.

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