Building heatwave resilience into our cities

Extreme heat events will increase in intensity, frequency and duration in the future due to anthropogenic climate change. Impacts will be felt across Europe, and cities in particular will be vulnerable due to their agglomeration of people, infrastructure, and economic activity. As we face such events of higher intensity and frequency and live in increasingly dense urban neighbourhoods, we must ask ourselves how to best design our living environments for the most vulnerable citizens – our children and the elderly. 

Many central and northern European cities are not properly prepared for extreme heat. Unlike other climate impacts, such as flooding, this threat is invisible. But urban environments are home to more of us than ever before – while half of Europeans (52%) were urban dwellers in 1950, the numbers had increased to 74% by 2015, with the trend set to continue.

While climate threats like flooding receive a lot of attention because of their vast economic impacts, the threat of extreme heat does not. More European citizens die from heatwaves than natural hazards like flooding, pollution, wildfires and earthquakes. Cities have got to decide how to address this threat, while improving their sustainability and liveability.

Certain groups in cities are more vulnerable to heatwaves than others, such as young children and older people. While the proportion of younger people in Europe is not set to change, Europe is getting older, and the elderly are particularly at risk. In Europe, the number of people over 65 is rapidly increasing, with those over 80 expected to more than double from 5.6% in 2018 to 12% by 2060. Cities will face multiple shocks and stresses in the future, with the vulnerable usually paying the highest price.

Impacts on health – and life

Between 2000 – 2018, floods – a visible threat that governments spend a lot of money on mitigating – killed over 700 people across Europe. But in comparison, in just one year the death toll due to extreme heat across Europe exceeded 70,000 people. This was in 2003, the deadliest year in recent European history (not including 2020 owing to the coronavirus crisis).

As well as increasing mortality, heatwaves impact hundreds of millions more every year in the form of health problems, water shortages, power blackouts, wildfires, pollution and infrastructure damage. Furthermore, when temperatures indoors or outdoors exceed 25°C, worker productivity declines by 2% per degree on average. Such declines in productivity can have huge economic impacts.

Extreme heat events are linked to a multitude of health impacts: dehydration, heatstroke and exhaustion, increases in incidence of disease and increases in premature death. The elderly, infants and young children, those with pre-existing health problems and those in hospital or bedridden are most at risk.

While these groups are physiologically more sensitive to heat, how people subjectively experience heat is also important and depends on a complex interaction of many factors:

1. Physiological. Previous long periods of hot weather can result in physical acclimatisation, reducing the negative impact on the human body.
2. Local climate. Humidity, air temperature, shading and windchill all impact on how heat is experienced.
3. Socio-economic. Being socio-economically disadvantaged affects your experience of extreme heat – for example, due to the quality of available housing, the availability of affordable mitigation measures like air conditioning, and proximity to green spaces.
4. Psychological. Spending time in urban greenery can improve perceived well-being, alleviating the perception of thermal discomfort. While the proportion of younger people in Europe is not set to change, Europe is getting older, and the elderly are particularly at risk. In Europe, the number of people over 65 is rapidly increasing, with those over 80 expected to more than double from 5.6% in 2018 to 12% by 2060.

We know that both the old and the young are more physiologically sensitive. People over the age of 65 are more vulnerable to heat, and this vulnerability increases with age. Infants younger than one are particularly impacted by heat-related mortality due to the weakness of their thermoregulatory systems.

The young and the old also experience hot weather in a particular way, depending on their own vulnerabilities and routines and the routines of the people who care for them. It is important to understand the experiences of the most vulnerable to ensure that we build resilience in a way that adequately caters to their needs.

Older people increasingly live alone, which raises questions about their accessibility to nearby facilities and social integration. They might also rely on caregivers in nursing homes or hospitals, highlighting the importance of healthcare quality and management. Children’s caregivers shoulder a huge responsibility for their well-being since children are unable to care for themselves. Spaces where children spend their time – nurseries, schools and playgrounds – all add to their experience of heat.

Heatwave response and management

As we attempt to build resilience into our urban environments, we must remember the key steps to take. Data is crucial for increasing the capacity to prepare for challenges. What might a city resilient to extreme heat look like for a 2-year-old and an 80-year-old? Read more about what we can do to build resilience to extreme heat events here.

1. Prepare: Data is crucial for increasing the capacity to prepare for challenges. In a city with a strong capacity to prepare, the municipality has conducted research on important thresholds and criteria particularly for vulnerable groups. Risk and vulnerability assessments pinpoint the particular threat to our 2-year-old and 80-year-old.
2. Absorb the challenges: A city with a strong capacity to absorb can dynamically cope with an extreme heat event, while maintaining public functions and avoiding negative impacts. Our 80-year-olds and 2-year-olds change their behaviour in response to a heatwave, for example by drinking more water, taking midday naps and shifting routines to earlier in the day. Families and communities check on each other.
3. Recover. The third approach to building resilience is to enable a quick recovery. The availability and accessibility of resources that allow quick recovery is essential. For example, emergency financial support is made available to schools and care homes. Information is freely available and effectively communicated to caregivers and vulnerable groups during a heatwave.
4. Adapt. In cities that have a strong capacity to adapt, reflective learning is key. This relies on adequate data collection during a heatwave event. Stakeholders at all levels, including in schools, hospitals and care homes, can then see what went wrong, what was done right, and how to improve the experience of our 2-year-olds and 80-yearolds the next time around.

We understand the facts and figures around the problem of heat in cities and can visualise how it impacts our most vulnerable. But beyond heat, cities face a myriad of other potential threats that disrupt their functioning. These include shocks and stresses like natural disasters, financial crises, terrorist attacks and biodiversity loss32, not to mention the spread of infectious disease as experienced during the coronavirus pandemic. Because of the global nature of our world, these threats intersect and interact, making their nature, magnitude and impact difficult to predict.

We also need to be able to look ahead. What do we want our future and the future of our children to look like? We must be equipped to face whatever the future holds, while ensuring that cities remain liveable, healthy, attractive and functional.

So, how can we prepare for not only a future of higher temperatures, but one that holds a host of other challenges, particularly for our most vulnerable?

Read our full Urban Insight report on building resilience to heatwaves

The answer lies in building resilience into our cities and society at large. Being resilient helps us – and our communities and cities – to manage the interconnectedness of all these challenges. It enables us to prepare and quickly and recover from challenges without being impacted too negatively. But it’s not just about quickly returning to business as usual: it’s about learning and positively adapting to a new normal, and even transforming our systems and their ingrained societal inequities that affect the way people are impacted in the first place.

Building resilience can focus on strengthening four capacities: the capacity to prepare for threats, to absorb them and quickly recover when they occur and to adapt and transform the way we cope in the future. This conception of resilience is based upon academic literature that synthesises the vast array of research on the topic.33

Sweco has an innovative portfolio of technological tools available for managing the threat of extreme heat. More passive building designs and dynamic thermoregulation through building envelope shading are good examples. Another example is improved and innovative spatial planning techniques for integrating urban resilience in plans and projects. Social solutions, like changing behaviours and establishing effective communication networks, are also vital. To discuss sustainable and climate action-focused engineering in more detail, contact us below.