Climate change is a killer - and a new study has found "substantial underreporting" in the numbers of deaths caused by environmental crises.

The research, published in journal The Lancet Planetary Health this month, revealed that over the past 11 years, the number of deaths attributed to excessive natural heat is at least 50 times greater than is recorded on death certificates in Australia.

During that time some 340 deaths in Australia were recorded as excessive heat but experts from The Australian National University (ANU) found that 36,765 could be attributed to the environmental conditions, following statistical analysis. The study indicates that the heat-related mortality rate in Australia is actually around 2 per cent.

The doctors noted that the intense summer bushfires in the country not only killed some of those directly fighting the blazes but also those who died prematurely from smoke exposure.

Dr Arnagretta Hunter, of ANU Medical School who co-authored the study, said in a statement: "Climate change is a killer, but we don’t acknowledge it on death certificates."

She pointed to the inclusion on death certificates of pre-existing conditions and other factors.

“If you have an asthma attack and die during heavy smoke exposure from bushfires, the death certificate should include that information. We can make a diagnosis of disease like coronavirus, but we are less literate in environmental determinants like hot weather or bushfire smoke.”

The researchers said modernisation of death certification is required to account for the impact of large environmental disasters. Other countries are exploring ways of modernising death records and the researchers say that it is imperative in order to get a true picture of the consequences of climate change.

"Understanding the degree to which environmental factors affect human health is important if the impact of climate change is to be fully appreciated," the study noted.

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