Heatwaves are particularly troublesome in cities, because cities are typically hotter than the surrounding countryside. Australia is the most urbanised nation on earth, with 60% of the population living in cities of one million people or more, which places our communities at significant risk of heat-related impacts.
One important way we can cool our cities and reduce the risk and severity of heatwaves, is by revegetating our urban areas. Not only is expanding our urban vegetation good for reducing heat-related deaths, but it can create jobs (helping with COVID-19 economic recovery), provide habitat for our native wildlife, and help address climate change by absorbing more carbon dioxide from the air.
This report presents evidence that strong action to increase urban vegetation will become imperative in our three largest cities to reduce serious heatwave impacts by 2060–2080, even with strong climate action. Without strong climate action — and continuing business-as-usual — Brisbane, Melbourne and Sydney will regularly experience temperatures above recommended health thresholds. Green infrastructure (like planting native trees and plants) takes time to establish to its maximum effectiveness, so acting early is critical for meeting future needs. This study also finds that local areas more vulnerable to additional city heat are typically more disadvantaged suburbs with lower levels of protective vegetation cover.
- Hot summer days in Brisbane and Melbourne are expected to regularly top 40°C by 2060-2080, and up to 50°C in Sydney, with a phenomenon known as the Urban Heat Island (UHI) effect likely to add several degrees on top of this in highly vulnerable suburbs.
- The areas most vulnerable to the additional heat caused by the UHI effect are typically disadvantaged suburbs with less protective tree canopy cover.
- Hobart is the only capital city that has more tree cover in 2020 than it did in 2013.
- More vegetation in cities helps address rising temperatures, improves physical and mental health, extends the life of infrastructure, captures carbon emissions, provides habitat for wildlife and reduces the economic burden of heat-related impacts.