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Expected health impacts of climate change in Aotearoa New Zealand
Part 4: Heat-Related Health, Physical Activity, and Ultraviolet Radiation
Aotearoa New Zealand is a country that ranges across latitude zones, has prevailing westerly winds, is completely surrounded by ocean and has a large mountain chain affecting east-bound weather systems. With a climate that varies from the subtropical to subantarctic, the country is in a unique position to experience a great number of health impacts from climate change.
Heat-related health
Worldwide, there are more than five million deaths due to extreme temperatures, and the rate of heat-related deaths has already seen an increase. The heatwave experienced by Europe in 2022 saw more than 60,000 people die from the heat itself (e.g., heatstroke, exhaustion), or from the heat putting undue stress on the body and contributing to underlying health conditions.
Elderly populations are particularly vulnerable to heat-related illness and death. In Aotearoa New Zealand it is expected that approximately a quarter of the country’s population will be aged over 65 by 2043. There is a likelihood that the percentage of heat-related deaths will increase as the population vulnerable to heat-related deaths increases.
The rise in the number of hot days will particularly impact people whose jobs require being outdoors (see part 3 for impact on the indoor environment). Where methods of cooling are unavailable, heat stress can contribute to, and exacerbate underlying conditions. Productivity may also be impacted. There is the potential that longer shifts with subsequently longer heat exposure may be required, or an increase in staff working in the heat may be needed to achieve past productivity.
Physical activity
When exercising, the body’s core temperature rises quickly but thermoregulation (the regulation of body temperature) happens more slowly. In hot weather, the body relies heavily on evaporation of sweat to cool itself. Sweat increases the rate of fluid loss, and heat stress and heatstroke can occur when dehydrated.
As temperatures rise, it may be important for public health messages around exercise to change. Encouragements could be made to exercise in the early morning or late afternoon, or to encourage indoor exercise. There are health impacts that result from a lack of exercise as well, so it is important to keep a level of physical activity.
Ultraviolet radiation
UV radiation is affected by changes in the ozone layer, and ozone depletion has contributed to climate change in the Southern Hemisphere.
Global food and oxygen supplies are impacted by changes in UV radiation. Too much can inhibit photosynthesis in plants and phytoplankton. Too little can impact production of nutrients for bacteria important to the ecosystem.
Aotearoa New Zealand has the highest rate of melanoma skin cancer in the world. The country has a multi-generational history of ‘slip, slop, slap and wrap’. Slip on clothing, slip into some shade, slop on the sunscreen, slap on a hat and wrap on some sunglasses. All of these are important in protection against UV radiation which can cause skin cancer. However, in addition to contributing to skin cancer, UV radiation is also responsible for the synthesis of Vitamin D in humans. Vitamin D is important for bone health and prevention of some diseases.
Much like plants, humans need a certain level of UV radiation to thrive. Climate change is impacting not only the amount we get, but also whether it is UVA or UVB radiation, with UVB being the most harmful.
As humans, we need to learn to adapt our responses to the changing outdoor environment. Though people already spend up to 90% of their time indoors, we cannot allow climate change to keep us indoors the remaining 10% of the time.
Check out part five for the impact of climate change on mental health.