Cities must better involve their public health agencies in plans to prepare for the impacts of climate change if their adaptations are to equitably help their citizens, according to a recent study in PLOS Climate. City officials must prepare for increasing threats to the physical and mental health of the most vulnerable urban residents both from direct effects, like heat-related illnesses and infectious diseases, and indirect effects, like the disruption of food supplies, public health experts warn.

Barcelona is one of the most densely populated cities in Europe, with about 1.6 million residents and a population that is expected to continue growing. Such growth, the urban heat island effect and large cities’ typical locations on coasts and rivers leave them disproportionately vulnerable to extreme weather brought on by climate change, with economically and socially marginalized communities hit the hardest. 

That puts big cities like Barcelona on the frontlines of climate change adaptation efforts that involve decisions affecting housing, mobility and employment. And metropolises also have an outsized impact on the drivers of global warming. While cities make up only a small fraction of the Earth’s land surface, they produce most of the world’s greenhouse gas emissions and consume the vast majority of the world’s energy. With many countries off-track to meet their commitments in the Paris Agreement, cities are increasingly stepping up with their own plans for reducing greenhouse gas emissions, as well as responding to the impacts of the changing climate and building resilience to them.

“The future of the fight against climate change is being played out in our streets and squares,” Barcelona Mayor Ada Colau Ballano said in the introduction of the city’s 2018 Climate Action Plan. “We are where most of the population lives, the people most responsible for greenhouse gas emissions and the main focus of innovation.”

Municipal public health services can make a difference in that preparedness, taking preventative actions and providing data that can result in better protection for those who need it the most, said the authors of the PLOS study released in March. The review of 22 large cities’ climate adaptation plans found that, while almost all of the cities’ plans involved goals for human health and all of them reported heat as a health concern, many did not involve their public health agencies in the plans, despite such collaborations being crucial to making climate adaptations more equitable. The study also showed that the highest-income cities had less involvement from their local public health agencies in addressing climate-related health risks compared to low- and middle-income cities. 

“We know as public health professionals, that public health has data and tools that can help target the most vulnerable people,” said Mary Sheehan, the lead author of the study. “But paradoxically, we’ve seen that public health is often on the sidelines of climate planning.”

Growing Populations and Increasing Climate Threats

The Intergovernmental Panel on Climate Change’s report focused on climate change adaptation earlier this year highlighted the widespread adverse impacts global warming is already having on human health. Infectious diseases, mental health problems, displacement, heat stress, malnutrition and other conditions are increasing as temperatures rise, according to the IPCC. 

Many of those impacts are concentrated in cities. Since 1980, extreme heat and rainfall have increased at least 500 percent in the largest cities in the world, directly threatening human health in urban areas around the globe, according to another study released last year. Such weather events also magnify the impacts of growing disparities in income and access to food and healthcare, and cities need to prepare for all of these impacts, especially as urban populations grow, the authors said.

Growing urbanization will increase vulnerabilities to such threats, especially in lower-income countries. Around the world, urban populations grew by more than 397 million people from 2015 to 2020, according to the IPCC report, with most of that growth occurring in less-developed regions. More than half of the global population now lives in cities, and that proportion is expected to grow to about two-thirds by 2050.

Sheehan’s study suggests that a lack of public health involvement in city planning for how to protect residents could leave the health and safety of the most vulnerable at risk.

Technicians at the Barcelona Public Health Agency said that the city and collaborating organizations consult with them about how and where to focus decisions on climate change mitigation and adaptation. Their role is to identify potential harms and help set preventative and protective measures, said Laura Oliveras Puig, one of the agency’s senior technicians. Opening  “climate shelters” in 11 schools for the general public to use in the event of a heatwave is one of the ways in which they collaborated. The shelters are made up of green spaces and water features, and the buildings were adapted to be thermally comfortable for people to use during climate emergencies.

“We focus on what is the prevention, promotion and protection of health at the population level,” said Oliveras Puig. “And we find at the end of everything we do as a public health agency is that it is all affected by climate change.”

According to the city’s adaptation plan, Barcelona’s biggest climate-driven health concerns are heat-related illnesses and the spread of infectious diseases that have migrated to the area as the climate warms. On average, the city has experienced one heatwave every four years, but it is expecting about two to as many as five a year by the end of the century.

Efforts to protect residents’ health during heat waves include developing climate shelters within walking distance of all Barcelona residents, improving the thermal comfort of homes and operating a 24-hour medical services helpline and protocols to protect outdoor workers.

Through a partnership between its public health agency and other local service agencies, the city mapped the geographic distribution of different climate impacts, including heat-related deaths by neighborhood. They have also studied energy poverty across the city to identify the neighborhoods and groups more likely to need interventions. According to their climate action plan, the mortality rate of elderly people and babies increased by over 25 percent on extremely hot days. That data will be used to prioritize interventions during future heatwaves and to monitor the results of those efforts.

Barcelona’s findings of disproportionate effects from heat are consistent with other large cities, where the consequences of higher temperatures are unevenly distributed across populations, with socioeconomically disadvantaged communities more likely to live in dwellings with less-efficient insulation in hotter parts of the cities. Evidence also points to higher heat-related health risks among the elderly and young children. The vulnerability of children to heat is expected to worsen with growing urbanization and poor infrastructure, especially in South Asian and African cities, according to the IPCC’s findings.

The Barcelona Public Health Agency is also tasked with tracking the population’s access to food and water, the spread of infectious diseases and air pollution.

Less than half of the cities in Sheehan’s study engaged health agencies in their efforts to identify vulnerable populations. But tracking data to map vulnerability can allow for more targeted actions to help the people who need it the most, she said. Her study was a pilot aimed at understanding the level of health agency involvement in cities’ climate adaptation planning. She plans to conduct a new review of a wider pool of cities that is more diverse in income categories and regions by the end of this summer.

Still, there is only so much public health agencies can do, particularly as wealth gaps in cities grow.

Gentrification, which contributes to disparities in access to affordable housing and healthy food choices to put vulnerable communities’ health at risk, is one of the biggest barriers to sustainable climate change adaptation in Barcelona, according to Isabelle Anguelovski, director of the Barcelona Lab for Urban Environmental Justice and Sustainability. Eradicating energy poverty, stabilizing rent costs and expanding affordable housing and green spaces can lessen the negative impact climate hazards have on already burdened communities, according to Anguelovski.

Mainstreaming public health across different city agencies as they work to adapt to a changing climate helps create awareness of warming’s impacts on public health, said City of Barcelona Sustainability Coordinator Irma Ventayol. City agencies that oversee food safety and nutrition, energy and housing, along with about 1,800 organizations and entities, including schools, are involved in sustainability planning in the city, she said. In order for everyone to collectively protect residents’ health from climate risks, “they have to believe that this problem exists,” she added.