The built environment, climate change, and health

The National Climate Assessment (NCA) is an inter-agency project conducted by the United States federal government to track the latest estimates of how climate change could impact the country and to evaluate ongoing prevention, mitigation, and adaptation efforts. The collaboration released their first NCA report in 2000 reflecting the latest knowledge at that time. They have written updated reports as new research has been conducted and new policies and community efforts have come into play. They just released the final portion of their fourth report (NCA4), which says that climate change will increase risks to human health and that there are many factors related to land use, transportation systems, and engineering that impact how extreme those risks could become. Fortunately for us, they provide a ton of ideas on how planning and engineering professionals can reduce the impact on climate change, and ultimately on human health.

There are multiple ways the built environment causes or exacerbates climate change. It can encourage human behavior toward carbon-intense activities and can reduce those natural resources that mitigate the impact of pollutants. As currently practiced in North America, “infrastructure design can lock in fossil fuel dependency, so urban development patterns will continue to affect carbon sources and sinks in the future.” This is in large part because “current infrastructure and building design standards do not take future climate trends into account.” Fortunately, “benefits to health arise from explicitly accounting for climate change risks in infrastructure planning and urban design.”

Health impacts of climate change

Climate change impacts human health by changing the climate norms from what local communities are used to and by “exposing more people in more places to hazardous weather and climate conditions.” The NCA4 report focuses on four main health outcomes that are likely worsened by climate change in the United States:

In the diagram below, the built environment mostly appears in the left-hand box titled “environmental and institutional context.” What is not stated here is how our land-use decisions influence and cause the problematic “climate drivers” in the first place:

"Conceptual diagram [that] illustrates the exposure pathways by which climate change could affect human health." From 4th National Climate Assessment, Nov. 2018
“This conceptual diagram illustrates the exposure pathways by which climate change could affect human health.” From 4th National Climate Assessment, Chapter 14: Human Health, Nov. 2018

Certain populations, such as people with low incomes, those who live in areas without resilient access to community resources, and the elderly, are at particularly high risk because they are more vulnerable to instability. As well, “people without access to housing with sufficient insulation and air conditioning (for example, renters and the homeless) have greater exposure to heat stress.” Unequal access to community planning processes can exacerbate these inequities and lead to worse overall community outcomes. “Decisions about where to prioritize physical protections, install green infrastructure, locate cooling centers, or route public transportation have differential impacts on urban residents. If urban responses do not address social inequities and listen to the voices of vulnerable populations, they can inadvertently harm low-income and minority residents.”

There are labor issues to consider as well. Many jobs can be at least temporarily affected by extreme weather events and can be permanently eliminated after natural disasters. These labor impacts put economically vulnerable families at higher risk of health issues, and when they disrupt supply chains can impact entire communities.

Further, current public health and healthcare systems might not be nimble enough to adapt or scale their services when large unexpected events happen. Further, “when climate stressors affect one city sector, cascading effects on other sectors increase risks to residents’ health and well-being.” And of course, when resources become scarce, there are complex geopolitical effects such as increased likelihood for war, mass migration, and other destabilizing social events.

Built environment fixes

The good news is that there are many ways to use the built environment for prevention and mitigation of some of these health effects from climate change. “Adaptation efforts outside the health sector can have health benefits when, for example, infrastructure planning is designed to cool ambient temperatures and attenuate storm water runoff and when inter-agency planning initiatives involve transportation, ecosystem management, urban planning, and water management.”

The report authors stress the importance of consciously deciding to think about health. “Adaptation measures developed and deployed in other sectors [than healthcare] can harm population health if they are developed and implemented without taking health into consideration.”

Of note, the NCA authors explicitly call out the role of design professionals:

“Local efforts include altering urban design (for example, by using cool roofs, tree shades, and green walkways) and improving water management (for example, via desalination plants or watershed protection). These can provide health and social justice benefits, elicit neighborhood participation, and increase resilience for specific populations, such as outdoor workers.

“Adaptation options at multiple scales are needed to prepare for and manage health risks in a changing climate. For example, options to manage heat-related mortality include individual acclimatization (the process of adjusting to higher temperatures) as well as protective measures, such as heat wave early warnings, air conditioning at home, cooling shelters, green space in the neighborhood, and resilient power grids to avoid power outages during extreme weather events.”

Design policy is deemed important as well:

“Incorporating climate projections into infrastructure design, investment and appraisal criteria, and model building codes is uncommon. Standardized methodologies do not exist, and the incorporation of climate projections is not required in the education or licensing of U.S. design, investment, or appraisal professionals. Building codes and rating systems tend to be focused on current short-term, extreme weather. Investment and design standards, professional education and licensing, building codes, and zoning that use forward-looking design can protect urban assets and limit investor risk exposure.

“A handful of cities have begun to take a longer-term view toward planning. These cities have developed adaptation plans, resilience guidelines, and risk-informed frameworks. However, they do not yet have a portfolio of completed projects. Adaptation planning is not always informed by technical analysis of changing hazards, climate vulnerability assessments, and monitoring and control systems. U.S. cities can examine methods and learn from completed projects, such as those developed by Engineers Canada and UKCIP Design for Future Climate. Managing climate risks promotes the integrity, efficiency, and safety of infrastructure to ensure reliable performance over the infrastructure’s service life.”

To better understand how the built environment influences and mediates climate change effects, and how these effects impact human health, read these key chapters from within the 4th National Climate Assessment: