The economic impact of urban heat islands
Urban heat islands (UHIs) – urbanised areas that experience higher temperatures than outlying areas – are a significant concern for cities worldwide, with far-reaching economic impacts that affect public health, infrastructure, energy consumption, and emergency response efforts.
Public health
One of the most immediate economic impacts of UHIs is the strain they place on public health systems. High temperatures in urban areas can exacerbate health issues, increasing heat-related illnesses and hospital admissions. Vulnerable populations, such as the elderly and young children, are especially at risk.
Physical infrastructure
UHIs also have an impact on infrastructure. Prolonged exposure to high temperatures can cause materials to deteriorate faster, compromising the structural integrity of buildings, roads, and bridges, causing safety hazards for motorists and pedestrians. Moreover, the need for frequent repairs and maintenance to address heat-related damage increases the financial burden on local governments and transportation authorities.
Wildfires
While forest fires may not immediately come to mind as a consequence of UHIs, elevated city temperatures can dry out surrounding vegetation and alter weather patterns, which collectively increase the risk of wildfires, particularly in areas with dense vegetation and dry conditions.
In addition to causing extensive and unpredictable damage, wildfires worsen climate change by releasing stored carbon dioxide and other GHGs into the atmosphere, diminishing the Earth's ability to sequester carbon, altering surface properties to absorb more solar radiation, and contributing to feedback loops that increase the likelihood of more severe wildfires in the future. In 2020, the US experienced one of its most severe wildfire seasons in history, with over 10.3 million acres burned and an estimated $16.5 billion in damages.
The trouble with A/C
Many urban communities rely on air conditioning (A/C) to maintain comfortable indoor temperatures. This strategy can exacerbate the problems associated with heat islands, however, because A/C units consume large amounts of electricity as they extract moisture from the air and lower its temperature, putting strain on the energy grid and generating a lot of heat in the A/C unit itself. Studies indicate that cooling alone use up 10% of the nation's total electricity demand.
As temperatures around the globe rise and UHIs intensify, the subsequent rise in costs and GHG emissions perpetuates and exacerbates the heat island effect, creating a vicious cycle of environmental degradation and financial strain. In the UK, buildings account for 59% of electricity consumption, approximately 31 MtCO₂e of indirect GHG emissions.
Evaluating the cost and finding a solution
To determine how dramatically the urban heat island effect could compound the losses expected from global warming, an international team of researchers undertook a global study that analysed 1,692 cities worldwide. On average, economic losses attributable to heat island effects will represent 5.6% of cities’ gross domestic product (GDP) by 2100, but this can be as high as 11% for the hardest-hit cities. Even under the lowest CO₂ emissions scenarios, the costs to cities could be as much as 30% higher than they would be without UHI effects.
Addressing the multifaceted economic and environmental impact of UHIs requires a comprehensive approach. By catalysing behaviour change, transitioning away from fossil-fuel-based energy sources, improving building energy efficiency, and implementing passive cooling strategies, cities can mitigate the adverse effects of UHIs. Such measures not only reduce healthcare expenses and prolong infrastructure lifespan but also curb energy consumption and minimise the risk of wildfires. Investing in innovative and sustainable solutions is not just about safeguarding public health and safety; it is an essential step toward fostering resilient, sustainable urban environments that can withstand the challenges posed by UHIs and contribute to long-term economic prosperity and environmental stability.
Sources
2 https://www.theccc.org.uk/wp-content/uploads/2020/12/Sector-summary-Buildings.pdf
