Lauren Fuge
Extreme heat is behind 7.3% of the heart disease burden in Australia, according to new research. This translates to an average of 49,483 years of healthy life lost to cardiovascular disease each year – and this figure could more than double by 2050.
Cardiovascular disease is the leading cause of death globally and in Australia, and it is sensitive to extreme heat.
“When the weather is hot, our hearts have to work harder to help us cool down,” explains lead researcher Peng Bi, environmental health expert from the University of Adelaide.
“This added pressure can be dangerous, especially for people with cardiovascular disease.”
Researchers have been sounding the alarm about the different ways climate change poses a fundamental threat to human health, including heat exposure, extreme weather events, air pollution, and the increased transmission of deadly infectious diseases.
These factors can worsen the symptoms of existing health conditions, from asthma to mental health to heart disease.
“Many of us have experienced how a warming climate can make us feel unwell, particularly during longer periods of extreme heat,” Bi says.
“However, it’s still not clear exactly how many people are living with serious heart disease or dying early because of higher temperatures, and we need to understand how this burden will increase in the future.”
Delving into the data
To begin to quantify this, Bi and colleagues drew on the Australian Burden of Disease Database to look at illness or death caused by cardiovascular disease. Focusing on a 15-year period between 2003 and 2018, they applied a statistical model to determine how much of this illness or death could be attributed to heat in different areas of the country.
They found that over this period, Australians lost an average of 49,483 years of life each year to cardiovascular disease attributable to high temperatures. These are referred to as disability-adjusted life years (DALYs).
Most of these years were lost due to death, not illness. The highest burden was in South Australia, while the lowest was in the Northern Territory.
But the team wanted to see how these numbers might change in the future – which will depend on what actions we take now to eliminate fossil fuel emissions and reduce the future impacts of climate change.
To account for the different paths we may take, they drew on two potential future scenarios used by the Intergovernmental Panel on Climate Change: a pathway where emissions stabilise and Austrtalia’s annual average temperatures increase by 0.6-1.3 °C by 2030, (Representative Concentration Pathway 4.5 or RCP4.5), and a business-as-usual pathway known as “high emissions” where emissions rise, population grows, and there are no adaptation efforts (RCP8.5).
In both cases, the research found that there would be a steady increase in cardiovascular disease burden.
Under the RCP4.5 scenario, Australians will lose 90,779.7 DALYs due to heart disease caused by hot weather by 2030, and 139,828.9 DALYs by 2050.
Under RCP8.5, the worst-case scenario, DALYs are projected to increase by to 95,343 by 2030 and 161,095 by 2050.
This means the cardiovascular disease burden would nearly double, as compared to the current baseline. The Northern Territory will see the most significant increase, in terms of rate and proportion of the burden attributable to hot weather.
“This study combines several key factors – climate change, population shifts, and adaptation strategies – to give a full picture of the disease burden across Australia,” Bi says.
“This makes our study one of the first of its kind globally.”
Though the research is based on Australian data, its findings will also apply more broadly.
“While the specific risks may vary depending on local climates, population demographics and levels of adaptation, the overall trend – that higher temperatures lead to more cardiovascular disease burden – is likely relevant in many parts of the world,” Bi says.
Next steps
The most effective way to reduce the health impacts of climate change is to stop burning fossil fuels and begin the process to curb rising temperatures.
But the impact of hot weather on heart disease can also be significantly lowered using adaptation strategies.
These include individual measures like staying hydrated, remaining in a cool place and seeking medical help. However, adaptation strategies also need to be structural, as Bi and colleagues points out in their paper.
“As adaptation capacity can be related to socioeconomic status, financial support for cooling and subsidies for air conditioning/electricity costs may likely benefit those with fewest resources,” they write.
“Furthermore … it is prudent for clinicians to provide practical advice relating to increasing fluid intake and plant-based diets, reducing outdoor activity levels, and guidelines for storing heat-sensitive medications.”
The study highlights the urgent need for improving public health policy in relation to climate – “including urban cooling plans, public health campaigns and improved emergency responses during hot weather,” Bi concludes.
Their study is published in the European Heart Journal.