How ready are we for the next heatwave?

The summer is in full swing, and the UK has already experienced the first sustained period of hot weather. In 2022, the thermometer reached unprecedented temperature levels for July in the United Kingdom (UK) (40.3°C was recorded at Coningsby in Lincolnshire on 19 July 2022), setting a new high-temperature record. How hot will it be this summer? The Met Office annual global temperature forecast for 2023 suggests that this year will be one of the Earth’s hottest years.

Heatwaves are similarly breaking records worldwide, and, considering the latest report from the Intergovernmental Panel on Climate Change (IPCC AR6), the frequency and intensity of hot extremes will continue to increase. Although the UK currently experiences heatwaves with a lesser frequency and intensity compared to other European countries, the projections suggest that within the following decades, hotter and drier summers are likely to become more common, and the chance of seeing more than 40°C temperature occurrences in the UK seems more and more likely. Considering that El Nino will likely create conditions hard to predict, there is an urgency to take action to reduce societal risks from extreme weather occurrences such as heat.

What are the implications of extreme heat, and how can we build heat resilience in our cities?

Extreme heat tends to escape our attention as a hazard due to the ‘silent’ effects, or the difficulty in quantifying its impact due to the lack of data. Yet, the World Health Organisation considers heatwaves one of the most dangerous natural hazards to human health. Without a doubt, extreme heat has the potential to give rise to mortality and morbidity, challenge critical infrastructure, networks, social services, and business resilience, and enlarge social inequalities. The impact of extreme heat in areas with dense concentrations of buildings and paved surfaces can be even more significant, as these structures absorb and amplify heat, especially with limited green space. The urban environment tends to be warmer than the surrounding suburbs or rural areas, especially at night, an effect called Urban Heat Island.

Some of the implications of extreme heat conditions

The impacts of heat extremes can be catastrophic, as historically shown by many heat-related deaths; from 1998-2017, more than 166,000 people died due to heatwaves, including more than 70,000 who died during the 2003 heatwave in Europe. Last year’s heatwave caused over 20,000 heat-related deaths, with the UK alone recording the largest number of excess deaths between June and August, according to the Office for National Statistics and UK Health Security Agency. Undoubtedly, heatwave conditions can lead to increased heat-related mortality and hospitalisations. This can be exacerbated by poor air quality conditions in urban areas, wildfires, and blackout events, all common during extreme heat events.

Extreme heat puts pressure on critical infrastructure and essential services such as transport, utilities, and public services like emergency response and health services. Heatwaves increase the demand for cooling, with increased energy costs and the risk of power failures due to surges in demand, which can compromise transport, communication, water, and fuel supply. Typically, the number of blackout events increases during the summer when electricity demand is at its peak. Also, within aviation, rail and road transportation, extreme heat can lead to damage to transport infrastructure (for example, damage to the overhead electric wires in rail or damage to pavements and airport runways) and service disruption (for example, introducing speed restriction, route cancellation and delays). These events can also impact supply chain and distribution networks, challenging business resilience and creating operational challenges as people cannot get to work.

Heatwaves also impact labour productivity, especially in construction, agriculture, and outdoor services industries. Production interruptions may occur during heatwaves because of policy enforcement or health and safety considerations, affecting workers’ income and the global economy due to reduced output. These effects will likely be more significant to vulnerable societal groups, increasing existing inequalities or leading to migration.

Although the effects of heat are likely to be exacerbated in urban environments, non-urban or rural communities can also be affected by hot conditions. Extreme heat can challenge crop production and livestock mortality or impact ecosystems’ function and vulnerability. There is high confidence that heat extremes have led to the loss of hundreds of local species, with mass mortality events recorded on land and in the ocean (IPCC AR6).

What can we do to be better prepared for the next heatwave?

The exact nature of risks emerging from extreme heat conditions is not typically easy to identify using traditional risk analysis and management approaches if we fail to consider the interconnectivity and interaction of systems. Also, it is essential to consider the existing levels of risk perception and elements that reflect actions towards building adaptive and recovery capacity and integrate them into the analysis. With heat waves projected to increase in frequency, intensity, and duration, cities must develop an approach to reduce heat-related impacts. To develop such an approach, we should invest in proactive action, building anticipation, enhancing preparedness levels, and ensuring an efficient response mechanism.

Elements of proactive action to reduce heat-related impacts in cities

One of the most critical elements in proactive action is understanding how a heatwave might impact our cities, from infrastructure/assets and operations/services to communities and ecosystems. Organisations need to comprehensively understand the heat-related risk over the short and long term and the existing vulnerabilities (physical and social) to plan for resilience. Many factors influence related risks, and a balance is needed to ensure that climate change mitigation and adaptation actions are well aligned. For example, if not naturally ventilated, an energy-efficient and well-insulated building can become uninhabitable if there is a power outage during a heatwave. As part of this process, it is critical to identify hotspots in terms of areas that are more exposed to heat due to

• the location (for example, urban centre or suburbs),
• building characteristics (materials, efficiency, ventilation), functions and
• related vulnerability (e.g., transport infrastructure and networks, hospital, school, care homes etc.).

An analysis of the vulnerability and existing levels of adaptability considering the evolution of heat hazards due to climate change influence will identify areas to focus on to build further resilience.

Build adaptive capacity into current urban systems and assets and integrate adaptation into local investment plans.

When designing or retrofitting, adopt more stringent specifications, building codes and safety standards aligned with the requirements of the future and consider adaptive opportunities that can enable infrastructure, assets, or buildings to increase resilience to heat. For example, consider passive cooling measures such as cool roofs, cool pavements, or improved building design to reduce heat retention (for example, green roofs, shading and natural ventilation), ensure that existing cooling capacity can address future needs, or the specifications of building and infrastructure material are fit for purpose. In newer construction zones, an option to explore is district cooling.

Adapt urban planning to reduce the urban heat island effect through nature-based solutions, especially in heat-vulnerable locations.

Approaches like urban greening, restoration of wetlands and ecosystems, and green and blue infrastructure are examples of approaches used to reduce the impact of extreme heat in the urban environment. Ecosystem-based adaptation approaches are generally effective in reducing urban heat while supporting carbon uptake and storage or, in some instances, flood risk mitigation.

A heatwave plan with specific steps to reduce risks to health for social services, critical infrastructure, buildings, and vulnerable populations is essential.

Having guidelines and a roadmap helps organise activities considering the dynamic nature and interconnectedness of the urban environment. Successfully developing a plan requires cross-departmental collaboration to include emergency management, health and social services, city planning, meteorological services, infrastructure operators, and transport authorities, to name a few. The development of the heatwave plan needs to consider different climate scenarios and the scale of likely impact and related interdependencies and should be updated regularly.

Maintain an early warning system.

Many countries have introduced heatwave early warning systems in response to the mortality and morbidity of recent heatwave events. Early warning systems are designed to reduce the health consequences of heatwaves that can be avoided; they involve forecasting the heatwave effect, predicting possible health outcomes, and triggering timely notification of prevention measures to vulnerable populations. For example, the UK Health Security Agency has recently updated the Adverse Weather Alerting service for England to include heat-health alerts, providing advanced warnings to healthcare professionals and the public to prepare. Another practice that cities have started applying is categorising and naming heatwaves based on their effect on human health, a practice followed in the case of storms.

Raising awareness is also essential.

Many councils conduct public awareness campaigns to increase knowledge of heat-related risks and heat risk reduction strategies; they provide information on what to do before, during and after a heatwave.

Update existing policies to become more climate-informed to allow mitigation of risks and taking advantage of opportunities.

In many cases, urban planning policies are based on historical data, limiting the ability to efficiently address the dynamic nature of climatic change and relevant implications. Having informed policies in place is crucial as it allows decision-makers to proactively act to identify interventions to facilitate effective adaptation. This requires using current scientific knowledge of climate change and a comprehensive analysis of the implications of extreme heat.

What decisions would you make differently if you had more clarity on climate risk and resilience?

Contact us to discuss how we can help you better understand heatwave-related implications.