When is a thing that is definitely a thing, not a thing? When you’re a thinktank trying to convince Coalition MPs they shouldn’t be backing policies to help Australia reach net zero greenhouse gas emissions.
As reported by Guardian Australia, the Centre for Independent Studies (CIS) gave a presentation to Coalition MPs in Canberra this week, telling them “heat deaths aren’t a thing” as part of a briefing to convince them to go cold on policies to get greenhouse gas emissions to net zero.
The CIS is a free market thinktank which – like many other thinktanks in Australia – does not disclose its funding. Most recently, the CIS has been critical of the shift away from fossil fuels to renewables in Australia while advocating for nuclear energy.
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So what is this thing that is not a thing all about?
One slide presented to MPs was headlined “Heat deaths aren’t a thing” and pointed to a technical report on health that was released in September as part of the National Climate Risk Assessment.
The CIS displayed charts showing estimates of temperature-related deaths for Sydney and Melbourne and claimed the risk of dying from cold was apparently greater than the risk from extreme heat.
The CIS pointed to the grey part of the curve that shows the risk from current conditions – rather than the green area that showed the risk if the world hits 3C of global warming.
The point of the risk assessment was to outline the risks from future climate change – or, to put it another way, the green part of the chart is the important bit.
That green curve shows how global warming increases the risk of deaths from heat in the two cities.
At 2C of global heating, the risk assessment said the number of estimated heat-related deaths in Sydney would rise by almost 200%. In Melbourne, they would more than double.
A spokesperson for the Australian Climate Service, which compiled the risk assessment, said: “Australia’s National Climate Risk Assessment analysed a range [of] locations around Australia – including Melbourne, Sydney, Adelaide, Bundaberg, Sunshine Coast, Townsville, Cairns, Darwin and Perth.
“This analysis shows increases to heat-related mortality are likely at all these locations at a global warming level of 3C.”
The spokesperson said extreme heat added risk “for many of the top causes of death, including cardiovascular disease, kidney disease, dementia and diabetes”.
“Heat deaths tend to occur over a few days, which has the potential to have a significant burden on the healthcare system, while cold deaths tend to be distributed over a longer period, with lower impacts on the healthcare system.”
Bad or good timing?
The timing of the thinktank’s claim was bad (or possibly good if you didn’t want MPs that are paying attention to challenge the claim) given the release just a couple of days later of a report from the medical journal the Lancet on health and climate change.
Rather than heat deaths not being a thing, the report found that between 2012 and 2021 there had been, on average, an estimated 546,000 heat-related deaths every year around the world – a 63% increase since the 1990s. That’s one death every minute.
Some of that increase was down to a rising population but not all of it. Heat-related deaths per 100,000 people had gone up from 5.9 to 7.2 – a 23% rise.
An Australian fact sheet released with the report found an estimated average of 980 deaths per year attributable to heat between 2012 and 2021 – an 83% rise since the 1990s, the report said.
Does more heat just mean fewer cold deaths?
Some climate science deniers like to claim that global heating will simply reduce the number of deaths from cold around the planet. The CIS was also drawing the attention of the Coalition MPs in the room to cold deaths.
Estimates vary on this question but previous studies have suggested there are more excess deaths associated with cold than there are with heat.
But Dr Thomas Longden, of the University of Western Sydney, has been arguing for several years that studies have been substantially underestimating the risk of extreme heat both now and in the future, and that the majority of deaths in Australia related to temperature are caused by heat, not cold.
He has argued that data taken from current death records could lead to a 50-fold underestimation of heat-related deaths, and that death records need modernising to include underlying causes.
“Heat deaths are definitely a ‘thing’,” he said. “But greater care needs to be taken in using statistical methods to measure excess mortality.”
One journal study this year looked at the net effect of rising global temperatures on temperature-related death in more than 800 cities. Would a reduction in cold deaths statistically cancel out the increase in heat deaths?
The answer across most of Europe was: no. Global warming saw large net increases in deaths related to temperature.
Cumulatively by the end of the century, global heating would cause between 616,000 and 2.3 million temperature-related deaths depending on how high greenhouse gas emissions were.
Heat deaths just ‘tip of the iceberg’
Government data in Australia shows that when it comes to extreme weather (think very cold or very hot days, or bushfires and storms), heat caused 7,104 hospitalisations between 2012 and 2022 – almost 10 times as many visits as cold did.
Prof Ollie Jay, the director of the Heat and Health Research Centre at the University of Sydney, said heat deaths tended to be concentrated in poorer communities but that mortality was only the most extreme example of how heat can hurt humans.
“Every heat death is preventable,” he said.
“But we know there is a vast array of non-fatal heat impacts that affect lives and livelihoods in profound ways across the human lifespan. We can think of deaths as being at the very tip of a very large iceberg.”
