Europe's summer heat wave has pushed tens of millions of people into temperatures above 35 degrees Celsius, broken records, and killed hundreds. In South Asia, temperatures have been edging past 45 degrees Celsius, forcing schools to close. Early climate attribution studies suggest Europe's event would have been "virtually impossible" just 50 years ago without human-caused climate change.
New Zealand has long enjoyed a mild, maritime climate that has kept it removed from those extremes. According to a report by Phys.org, new research shows that may not last. By the end of this century, peak summer temperatures in cities like Auckland and Christchurch could climb several degrees higher than they reach today.
The country's housing stock was not built for that kind of heat. New Zealand homes have traditionally been designed to retain warmth in winter. As temperatures rise, managing overheating will increasingly require either expensive retrofits or greater reliance on air conditioning, which has historically been uncommon in the country.
That is beginning to change. A recent survey found nearly three-quarters of households with heat pumps now use them for cooling. But renters, families with children, and Maori are all less likely to have access to space cooling, largely because of cost. Many low-income households already limit heating because they cannot afford it, and poorly insulated homes make those compromises worse, leading to worse health outcomes and higher health care costs.
Researchers used a computer model that simulated how households use electricity under different conditions. The model considered factors including income levels, outside temperature, and housing type, then estimated when people would choose to run air conditioning. They applied this across neighborhoods in Auckland and Christchurch, testing both midrange and high-end warming scenarios through the rest of this century.
The findings were significant. In the highest warming scenario, summer electricity demand overtook winter demand. Homes became more likely to overheat. By 2100, the model projected thousands of additional heat-related deaths each year, with the worst outcomes concentrated among the most vulnerable populations.
The research also found that greater access to heat pumps changed the results, suggesting that expanding access to cooling technology could reduce some of the health risk. But cost remains a barrier, particularly for the households that face the greatest danger from extreme heat.
The study connects two problems at once. As summers grow hotter, pressure on New Zealand's electricity system could shift from winter heating demand to summer cooling demand, a structural change the country's energy infrastructure may not be prepared to handle.
