Heat kills more people than cold or floods, yet nothing in the new government’s policies suggest anything other than marginal commitment help keep the heat down, writes Pat Baskett
Comment: We are warned: this coming summer will be hot. The dangers of exposure to the sun are familiar but are we about to learn that heat itself is a killer?
In Auckland it’s not just the sun that raises temperatures: humidity can have a fatal effect on how our bodies cope with heat. Physiologically we sweat when we’re hot because the moisture we produce cools us as it evaporates. But humidity prevents this moisture from evaporating and we become unable to sweat.
This means that a just-bearable temperature of 27 degrees, which occurs occasionally in Auckland, can be raised to the equivalent of 30 degrees when humidity is 80 percent. It’s known as the wet bulb effect and its potency increases exponentially.
The average humidity for Auckland is said to be 82 percent, yet on one Tuesday in early May this year humidity was 94 percent. This was attributed to an atypical waft of super warm air descending from the tropical Pacific. Autumn temperatures kept the air tolerable but should this summer cook us at 29 degrees and the humidity rise to 90 percent, we will experience that as if it were a lethal 37 degrees.
Last summer the warm air did what climate scientists expected it to do – it held more water. Which brought rain and more rain. So, if we don’t get deluges this summer, we will get high humidity – and the additional heating effects that El Niño is threatening to bring.
Heat is sometimes described as the silent killer. In estimating the causal factors in deaths attributable to the recent severe weather events worldwide – heat domes, rain falling in 'atmospheric rivers', our own devastating cyclones – heat is estimated as killing more people than cold or floods.
In the US, in the decade to 2022, heat-related deaths are recorded as up 95 percent. Last year’s extreme heat in the European summer is said to have been a factor in the deaths of more than 60,000 people. Yet just 20 years ago the European heatwave of 2003 was considered one of the 10 deadliest natural disasters for the past 100 years.
And so we prepare for the next disaster because we all know deep down that what happened here last summer and whatever happens next February-March is just the beginning of processes now beyond our control.
Nothing in the new government’s policies suggest anything other than marginal commitment to do as little as possible to contribute to keeping the heat down, globally.
And so we prepare for the next disaster because we all know deep down that what happened here last summer and whatever happens next February-March is just the beginning of processes now beyond our control.
Such apparent fatalism appears to contradict this year’s IPSOS research findings, which show that 80 percent of New Zealanders are worried about the impacts of climate change – and 31 percent agree government has a plan to tackle the problem.
The National Climate Change Risk Assessment’s reference to heat has a table showing the highest air temperature recorded as 39.2 degrees – in Ruatoria in 1973. More words are spent on drought and agriculture than on how to deal with heat in un-airconditioned classrooms and offices.
No mention of the needs of animals in the green, tree-less deserts that dominate our pastoral landscapes.
Meanwhile, our prior concerns are, understandably, to meet the needs of the thousands of families whose lives were displaced in the most recent disaster.
Retired environmental planner Dr Mairi Jay has taken a hard look at what climate scientists say we can expect in Auckland, and at what communities can do to mitigate the heat in their own environments. Her concerns have led her to offer presentations on her findings to Auckland’s local boards. So far she has visited Waitakere Ranges, Henderson-Massey, Hibiscus and Bays, Upper Harbour, New Lynn, Papatoetoe-Otara, Mt Eden-Three Kings and presented to Otara-Papatoetoe.
“I felt there was a serious gap,” she explains. “Councils are concerned with drains, traffic and building permits and the heating potential of a surfeit of sunshine hasn’t yet registered as a health hazard.
“It’s important to realise that heat will be experienced differently in different parts of the city,” she says. “Leafy, grassy areas and those with some elevation and sea breezes will make heat easier to bear than suburbs with less tree cover, more paved surfaces and where the topography is low.”
The correlation between tree cover and levels of prosperity is stark. Traditionally affluent Remuera, St Heliers, Howick, most of the North Shore, Waitakere and Howick have an abundance of trees – in gardens and along street verges – many of them years old.
The more economically struggling south Auckland suburbs of Mangere, Otahuhu, Manurewa, Otara and Papatoetoe have fewer tree-lined streets and tend to be on lower-lying land.
“We need to retrofit our public buildings, our schools and our shopping centres for cooling. And we need to have designated areas where people can go to get out of the heat,” she told local boards.
Home is not necessarily the safest or the coolest place to be.
“People without air conditioners will suffer,” Jay says. “Many of these will be in rental properties where landlords are required to provide heating for winter – but not necessarily heat pumps which can be used for cooling.
“And those who live alone can be unaware of becoming dehydrated. Loss of 5 percent of the body’s fluids through sweating can make you heat stressed and 10 percent fluid loss can lead to the more serious state of heat stroke.”
Those over 70 are particularly vulnerable because many have underlying conditions that are exacerbated by heat stress. Loss of salt and water can stress already-compromised body systems. About half of heat deaths are thought to be from heart attacks quickened by high temperatures. Pregnant women and infants are also particularly susceptible.
And then there are those who work outdoors and may have little or no shade – for instance road repair workers, and utility and service workers, as well as those in warehouses with no air conditioning or ventilation.
Overseas studies show that migrant and undocumented workers are particularly vulnerable to exploitation and poor conditions. Here, that could include seasonal fruit pickers and workers in market gardens where shade is non-existent and workers are paid by the lot rather than according to the hours worked.
There are no legally set limits for work in New Zealand, only recommendations that workplace temperatures remain between 19 and 24 degrees. Logically, production can only decline as the heat increases. In the US some changes have been made to working hours to avoid the hottest part of the day.
What are the symptoms to be aware of? Jay says: “Heat exhaustion can give you a fast, weak pulse, muscle cramps, nausea and headache or dizziness. So you need to go somewhere cool and drink water before you reach the more serious state of heat stroke which can make you lose consciousness. The best advice is to drink water every 15 minutes, even if you’re not feeling thirsty.”
But not that long cool glass of white wine. Alcohol can be dangerous in the heat, both through depression of the central nervous system and by causing diuresis, or urination, and consequent dehydration.
