As temperatures and Aotearoa’s elderly population rise, more people will be at risk from heat stress.
Heat already kills more than a dozen New Zealanders a year, and that is expected to get worse as temperatures increase.
Niwa climate scientist Gregor Macara said the number of days which felt uncomfortably hot would rise as global heating pushed up average temperatures and the frequency of hot extremes.
He had already noticed changes in seasonal weather summaries, even in his hometown of chilly Invercargill.
University of Waikato climate change lecturer Luke Harrington said the hottest days of the year had already warmed by more than 0.5C in many New Zealand cities.
Rising temperatures will make it difficult for the elderly to cope. Photo / 123RF
Auckland is expected to have more days above 29C or 30C.
Cities with smaller temperature ranges, such as Auckland and Hamilton, may face higher risks, research by Dr Harrington and Professor Dave Frame has shown. Because their temperatures are more even, their hot spells tend to be longer, with less reprieve overnight.
This would not just mean more beach days.
Harrington cites international research showing between 1 and 8 per cent of all warm-season deaths could be attributed to the weather.
Although New Zealand would not experience the extreme heat seen in places such as Australia, research from climates as varied as Scandinavia and the tropics showed adverse health impacts happened when temperatures soared above what was normal for that area, he said.
What counted as dangerously hot depended on what people were used to and what their built environment was like, with plenty of cooling trees and reliable air-conditioning helping, as well as behavioural adaptations such as “not going out for a run in the middle of the day”, Harrington said.
Heat deaths were often recorded under heart disease or other causes, said GP Dermot Coffey, a representative for OraTaiao: The NZ Climate and Health Council. But epidemiologists could look back on heat waves and work out how many people were tipped over the edge, who would otherwise have stayed alive.
Heat stress increases cardiac stress and the risk of renal failure, causing health impacts long before the point where a person would actually “cook” to death. But heat was often a less obvious killer than a climate-worsened storm event, such as the deadly flooding in Esk Valley in February, he said.
Most at risk are the elderly, young children, and those on common medications such as heart medicines or anti-depressants. These groups may not be able to regulate their body temperature quite so well, for example by sweating, Coffey said. People with mental health conditions such as schizophrenia could have a much higher risk.
Although research was ongoing, Harrington said early indications were that Māori and Pacific Islanders were also more vulnerable.
In Paris, vulnerable residents could sign up for a door-knocking service, to make sure they were okay when a heat wave hits. In Aotearoa, MetService had started a trial of heat alerts during the summer months.
Harrington wants the Government to introduce maximum heat standards for early childhood and aged-care facilities, which currently have minimum temperatures but no legal maximum.
If New Zealand kept building structures which did not keep vulnerable people cool enough, the country was setting itself up for greater health impacts down the line, he said.
Coffey“completely agrees” - and believed there should be standards already, in particular for aged care.
There was evidence heat could be an issue even at current temperatures.
In 2017, Robert Love told Consumer NZ his elderly mother Freda was left in a rest home room that was sometimes too cold and sometimes up to 33C, resulting in an apology from the company, Bupa. (The company also acknowledged other failings in her care).
The Ministry of Health said it was not aware of a maximum heat limit for aged-care facilities, but they were required to have a window and appropriate heating and ventilation.
The Ministry of Education said it was currently appointing a working group on early childcare, which might consider introducing maximum temperatures.
Macara said a major determinant of heat stress would be how much countries could reduce their greenhouse gas emissions by as the number of riskily hot days projected for the future was heavily dependent on the levels of heating emissions.
A recent UN review found the Paris Agreement had brought projected temperatures down considerably, but countries needed to do much more.
