Lead author Yuming Guo, an associate professor of environmental epidemiology and biostatistics at Monash University, says the findings are a warning to governments to introduce adaptation strategies such as better urban planning and public education campaigns.
"If the Australian government cannot put effort into reducing the impacts of heatwaves, more people will die because of heatwaves in the future," Assoc Prof Guo said as the study was published in the journal PLOS Medicine on Wednesday.
"The current heatwave in the northern hemisphere is serious and many people are concerned about their health.
"That highlights how important our study is in providing evidence for governments to do something, particularly in Australia where the government has cut off a lot of funding for climate change research."
Much of Europe, parts of Asia and North America have spent the past few weeks sweltering through heatwave conditions.
Canada and Japan have each recorded at least 30 heat-related deaths as temperatures soared during July.
Previous studies have warned of a future increase in the number and severity of heatwaves as a result of climate change, but the research by Assoc Prof Guo and his team is the first to look at the potential impact heatwaves may have on death rates around the world.
The researchers describe heatwaves as a critical public health problem because they can cause heatstroke and cramps, as well as induce the onset of conditions including cardiovascular disease, respiratory diseases and diabetes.
The models used to estimate future heatwave-related deaths included data on future greenhouse gas emissions, population growth, and hypothetical changes governments could introduce to help communities cope with warmer temperatures.
They then applied that data to estimate links between heatwaves and deaths in 412 communities across 20 countries.
They found that if governments don't introduce any measures to help communities adapt, heatwave-related deaths are expected to rise most in tropical and sub-tropical countries, with Colombia, the Philippines and Brazil facing the biggest increases.
If adaptations are made, mortality rates are still expected to rise in most countries but at a smaller rate.