Demand for Cooling to Increase Due to Global Temperature Rise

Countries like New Zealand, Canada, and Britain will likely see the greatest relative increase in the number of days that cooling will be needed each year as global temperatures rise.

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Researchers from the University of Oxford simulated likely temperatures around the world under 1.5 and 2 degrees of global warming to estimate the demand for cooling in different countries.

The study led by Jesus Miranda published in Nature Sustainability, shows that New Zealand is in the top 10 countries, tying third, with a nearly 24 percent relative increase in cooling demand days as the world moves from 1.5 to 2 degrees above pre-industrial levels.

The 2015 Paris Agreement recognized that 1.5 degrees above pre-industrial levels is a critical threshold beyond which the world enters "dangerous climate change," which will be experienced through more intense and frequent extreme events, like storm-induced flooding. It is also manifest on hotter days that cause heat stress.

This study measures the absolute and relative increase in cooling demands due to hotter weather, using a measure called "Cooling Demand Days." It shows that even a small increase in average global temperature affects heat exposure and cooling demand.

"New Zealand is not prepared for this impact. Climate and energy policies need to build resilience to a hotter local climate and the inevitability of heat stress," said Bruce Glavovic, professor of the School of People, Environment and Planning in Massey University.

The cross-party agreement is necessary to enact robust legislation, with enabling policies and resourcing, to reduce climate-compounded impacts and risk, he said, adding increasing heat stress and cooling demand adds to the litany of climate-compounded challenges in New Zealand as it navigates the aftermath of multiple flood disasters.

Nick Cradock-Henry, principal scientist of GNS Science, said as a mid-latitude nation, many of New Zealand's systems of production and distribution, and urban and rural populations are traditionally unprepared for high temperatures, and large-scale adaptation to heat resilience presents a novel, complex challenge.

This will affect the country's largest urban populations not only through higher temperatures but place additional demand on electricity supply, potentially straining already fragile infrastructure.

These findings also pose additional adaptation challenges for the primary industries, which rely on cool storage. Some 60 percent of New Zealand's food production or by-products are exported in a refrigerated state, he said, adding this presents an acute risk for cold chains, which are likely to face higher energy demands and costs.