Urban heat is an invisible threat – resilience against it shouldn’t be

For heat management, it’s about public education of the effects, making sure everyone has access to healthcare, looking at the availability and affordability of energy and cooling for indoors, as well as housing affordability. Cities will also need to monitor when those heat waves occur to be able to plan more effectively. For example, they might look to pursue cooling centres or having emergency shelters in place for those that don’t have safe and accessible cooling in their own houses, or for people experiencing homelessness. 

We conducted a survey of planners across the United States from a range of cities and climates and found that a majority of planners are concerned about heat already, and are aware that it’s a threat. When we asked them about the strategies they have implemented for heat, 73 per cent of cities said that they were pursuing urban forestry.  Emergency response was a top strategy as well, with 66 per cent using things like cooling centres. 

On the other side of that, we also found that regulating the built environment for heat was very low reported as a strategy, as was actually having staff tasked with dealing with heat. Only 8 per cent of those surveyed said that anyone in their community was tasked with thinking about heat – not even as a full-time job, just as part of their job. We’ve seen a lot of focus on urban greening, forestry and parks, but much less the actual urban development and the kind of regulation of the new built environment.

Bringing groups together that, traditionally, haven’t worked together on this topic before is probably the very first step for communities

Part of that is because heat is largely an invisible threat. The heatwave in the Pacific Northwest last year has a death toll of over 1,400 across Canada and the United States as it stands. Hurricane Katrina, which made landfall in 2005, killed over 1,800 people – the death tolls aren’t too far off one another. The big difference is that Hurricane Katrina obviously damaged property – it was much more visually striking to the human eye, and presented a much more perceptible risk.

There were significant national changes that happened at the Federal Emergency Management Agency (FEMA) based on our response to Hurricane Katrina, but there have been no substantial national policy changes in the wake of the Pacific Northwest heatwave. The stories soon dissipated after the event was over, despite heat being the number one weather-related killer in the United States.

What partnerships and collaborations should local governments, both at state and city level, look to make to help identify and deploy solutions that could help them combat urban heat? 

LR: Heat mitigation is largely conducted by planners and landscape designers. Heat management is largely public health and emergency management. The first thing for cities to do is get those two parties together to talk about heat, both on short-term and long-term scales, and also address chronic heat and acute heat events. Bringing groups together that, traditionally, haven’t worked together on this topic before is probably the very first step for communities. They have to begin to share all of the related information that typically and historically hasn’t been shared. 

Do you think we’re approaching a tipping point in terms of how urgently cities and governments now need to address heat as a serious threat to life and wellbeing?

LK: I think we’re certainly trending in the wrong direction as far as heat-related deaths are concerned. Where I’m speaking from in Arizona, we had 283 heat-related deaths in 2019; in 2020 that was up to 522 and preliminary data for 2021 has that number at 552. The questions that cities need to answer are who heat is affecting most and which populations are going to suffer the most.

At the highest level, we need energy grids that are reliable; the last thing anyone can afford to happen during a heatwave event is a blackout

The answer, mostly invariably, is going to be marginalised populations – lower income communities that don’t have access to indoor cooling or safe and reliable transportation, those without safe working conditions or lower quality cooling systems in schools. My concern is for the ongoing habitability of cities and for who they are going to become less habitable for as heat increases. 

How do you see the role of energy providers and utility companies changing over time in the way they work with cities on this? 

LK: Where energy is concerned, that’s when we really get into looking at governments on a wider scale. It’s not just local governments but state governments and central governments – those regulating the energy providers. At the highest level, we need energy grids that are reliable; the last thing anyone can afford to happen during a heatwave event is a blackout. That’s the nightmare scenario, where it’s not just those that are most vulnerable at highest risk, but a whole metropolitan area potentially without power. 

Arizona has the Corporation Commission to regulate the energy providers. The commission has been working to make sure that providers don’t conduct energy shut-offs in the summer due to lack of payment. If someone can’t afford their bills and their energy gets shut off in June or July, it’s a potentially deadly situation. 

Being based in Arizona, to what extent do you feel personally close to the issue of heat resilience, and do you think that resonates throughout the community as well? 

LK: We probably have a higher level of heat adaptiveness already because Arizona is historically a hot place, but there’s also a twin danger that in historically heat-adapted places we take the heat for granted, and downplay the action needed to do anything about it. I pointed earlier to specific numbers like the increasing death rates due to heat here, but what’s especially dangerous about historically hot places is that most deaths and heat-related illnesses occur outside of heatwave periods. Heatwaves are certainly more dangerous for us but there are another six months of the year where the temperatures are too hot for many people to safely be spaces that aren’t air conditioned.

That’s very different than historically temperate cities, like Seattle or Portland, where it is heatwaves that they’re concerned about, compared to places like Phoenix, Los Angeles or Miami, where there are large swathes of the year with chronically high temperatures all the time. It’s not just treating it like an emergency but making sure that people are safe throughout their entire respective hot seasons. 

What kind of work do city governments and local authorities need to do in order to engage with citizens about the threats of urban heat and how to stay safe? 

LK: It’s a matter of ensuring that the impacts of heat are better known publicly – and that’s not only the responsibility of local government, but researchers, practitioners and everyone else, too. One example of raising the awareness is in Phoenix, where they have nature trails within the city. They’ve done a better job in recent years of posting heat-related warnings and heat-related signage at the trails – especially for out-of-town vacationers who might not be familiar with the dangers of hiking and heat during the hot season.

Phoenix even went as far as closing some of those trails at the hottest times of year to ensure they’re not even taking a chance that people will go out by mistake and put themselves at risk. There’s a lot that cities can do at that individual level, but it all comes back to raising awareness about heat to ensure that people take it seriously. 

I’m part of a partnership through the CDC BRACE (Building Resilience Against Climate Effects) project at the moment, which is run through the Arizona Department of Health Services, Arizona State University in Phoenix, and the University of Arizona. Through that partnership, we have run annual Arizona heat planning workshops to discuss heat-related illnesses and deaths, and talk about state-wide actions for summertime heat planning. Those workshops are a great place to convene decision-makers to talk about heat as a risk. There are a few US states looking to this annual heat workshop as a model they would like to emulate to bring people together. 

What role can technology and innovation play in coping with the risks that rising urban heat can have? To what extent are solutions reliant on better planning and policy from cities and authorities? 

LK: In the ‘Planning for urban heat resilience’ guidebook, there’s a lot of discussion about the available information sources on heat and a lot of it is drawn straight from technology. There’s land surface temperature through maps that are nationally available, the CDC social vulnerability index, the way the National Weather Service is continually improving local forecasts, or the increasingly large network of climate sensors and cities that we can draw from to better understand the ambient air temperatures. There’s a lot of existing information out there and the guidebook helps to explain how communities can use that information, to at least either start addressing heat or advance their efforts to address heat. 

In terms of technologies or products that can help us decrease heat and mitigate heat, there have been some high-profile pilot projects – one of which I’m running in the city of Tucson using cool corridor pavement technology. In that project, we’re looking at different types of roadway coverings or asphalt treatments that better reflect the heat and ensure that roadways aren’t as big a source of heat collection for the urban heat island effect as they have been. Los Angeles and Phoenix have had a some of those pilot projects as well.

It’s critical that federal governments, across all their agencies, consider heat as a risk equal to or perhaps even greater than flooding

There are a lot of exciting product vendors that are looking at new products in this area. What’s important is the partnerships between cities and universities to evaluate and test how well they work in these different kinds of scenarios and places, and to ensure there are no unintended effects. 

Outside of cool pavements pilot projects, we need to know how well something like urban forestry really works in reducing the urban heat island effect. How effective are parks at reducing the urban heat island effect? What about social interventions? If a city opens cooling centres, are they really protecting and saving lives as a result? How many people are visiting, and if it’s not what you expected, are the right people being given the information about the availability of cooling centres? I think universities can play a really important role in helping governments advance all of those efforts and find answers to those questions. 

Governments are increasingly paying attention to heat as a risk – not just local governments but the federal government too. It’s critical that federal governments, across all their agencies, consider heat as a risk equal to or perhaps even greater than flooding. We’ve seen the federal government begin to integrate heat into their thought process, but there’s still a long way to go.  

Ladd Keith, PhD, is an assistant professor of planning in the School of Landscape Architecture and Planning at the University of Arizona. An urban planner by training, he has over a decade of experience planning for climate change with diverse stakeholders in cities across the US. His current research explores heat planning and governance with funding from the National Oceanic and Atmospheric Administration, Centres for Disease Control and Prevention, and National Institute for Transportation & Communities. He served a full term on the City of Tucson’s Planning Commission and chaired the development and adoption of the city’s comprehensive plan. He also founded and leads the Sustainable Built Environments undergraduate degree programme which is offered in person, fully online, and at the Universidad Peruana de Ciencias Aplicadas in Lima, Peru. He has a PhD in Arid Lands Resource Sciences and an MS in Planning from the University of Arizona.