As urban expansion generates ever more concrete and asphalt, new research suggests that sections of Australia’s cities will be up to 3.7 degrees hotter by the year 2050.
According to researchers from the University of NSW, the ”urban heat island effect” – rising temperatures in built-up areas – is going to amplify climate change, in particular along the suburban fringes.
”Today, if you’re living along the edge of a city, you’ll notice the change in temperature, mainly through the minimum temperature change at night,” says Daniel Argueso, the lead author of the study prepared at the Centre for Excellence in Climate System Science. ”There is also the fact that urban canyons prevent winds from moving around freely and cooling things down,” he said.
For decades scientists have studied the precise effects that urban heat has, although one simple test it is to simply touch a brick wall which has been exposed to full sun for an afternoon and yet remains warm long into the evening.
In addition to retaining heat longer than undisturbed earth or rock, artificial structures also absorb less moisture, meaning there is less cooling through evaporation.
Cities also produce more heat because there is a greater density of road traffic, electrical generators and industry, all of which generate small amounts of heat that all add up, and hang around for extended periods of time.
”The ground heat ﬂux daily cycle barely changes in the surrounding areas, but its amplitude increases considerably over areas of urbanisation,” according to the paper, Temperature Response to Future Urbanisation and Climate Change. ”This validates the picture of a surface with increased ground heat storage that is released later during the night.”