It’s an island no one in their right mind wants to be on, but sadly many of us increasingly find ourselves due to global warming.
“Heat islands” are a concept British climatologist Gordon Manley came up with way back in 1958 tied to the fact that the downtown cores of cities are often hotter than outlying areas. An observation that didn’t garner much notice or concern at the time. But in today’s world of record high temperatures from one year to the next, heat islands are an environmental challenge causing undue hardship for countless millions.
“The most dangerous urban health impact of climate change today by far is heat [and] vulnerable populations such as the elderly, children, and those with pre-existing health conditions are disproportionately affected by heat,” observes Giselle Sebag, Executive Director of the International Society for Urban Health (ISUH), a global organization dedicated to creating healthier, more equitable cities.
For pedestrians, Sebag observes that “heat islands mean increased exposure to heat, which raises the risk of heat-related illnesses such as heat exhaustion or heat stroke… and can make walking more physically demanding, leading to quicker dehydration and fatigue.”
Heat islands are caused by everything from the high concentration of dark, impermeable paved surfaces that cover approximately 40% of U.S. cities, high concentrations of buildings, reduced green space, urban “canyons” that restrict airflow, heat generated from human activities (e.g., air conditioning) and, as is experienced much more often now, severe weather conditions.
Far from just a near science fiction concept introduced in the 1950s, heat islands are now the new normal of urban dwellers. Thankfully, it’s also a threat that a growing number of cities take seriously enough to begin implementing a mix of short and long-term actions designed to help mitigate heat.
“One of the things that we focus on with a lot of our communities is to compile best practices to make cities aware of the sheer breadth of options that are out there on heat,” says Angelica Greco, Resilience Officer for ICLEI USA, which is part of ICLEI – Local Governments for Sustainability, a global network of more than 2,500 local and regional governments in 125+ countries committed to sustainable urban development. “Strategies that can vary from small scale such as creating pocket parks, community gardens, and shade structure all the way up to really large initiatives like creating green corridors or green belts or hiring a chief heat officer, which some cities have been doing.”
Apart from best practices, Greco says ICLEI USA also encourages cities to adopt “layering strategies” whereby they combine short, mid and long-term actions as part of a more balanced approach. “There is a combination of small-scale things we can do with quick wins,” she says, combined with initiatives that take longer to have an impact. “Because if a city is going to plant trees along a transit corridor, [the benefits] aren’t going to happen overnight.”
Starting on a smaller scale, one example Greco cites is a pop-up cooling center. “It could be a van, a tent or a splash pad, or doing a pocket park with a bench and some trees, all requiring relatively low effort. And any place where we’re replacing dark-colored pavements with lighter-colored surfaces we’re making a difference, even if it’s on a very small scale.”
Complementary measures listed by ISUH’s Sebag include setting up free public water stations to help prevent dehydration and temporary shade structures in public places frequented by pedestrians – such as parks and bus stops. And public awareness campaigns “to educate citizens about the risks of heat waves as they occur and precautions individuals can take to stay safe.”
When tackling the threat of heat islands on a wider scale in the years to come, Sebag points to the need for a more holistic approach. “Cities need to work collaboratively both within their own administrations and with the private sector and civil society to effectively address the complex and interrelated heat island challenge affecting urban residents,” she observes.
One way ISUH is helping to catalyze the adoption of best practices pertaining to heat islands and other challenges linked to sustainable development is through the group’s Accelerating City Equity (ACE) Project. “ACE maintains a priority focus on the impacts of heat islands on vulnerable residents around the world,” she says.
One example of this focus in action Sebag cites is a project in Ahmedabad, India, working with the Mahila Housing SEWA Trust.
“We did a deep dive into a cool roofs project initiative by a local grassroots organization [and] in partnership with women living in sprawling informal settlements who were suffering disproportionately from the effects of extreme heat and heat islands in the city.” She adds that “we believe these initiatives have a lot to teach American cities about strategies to adapt to the impacts of extreme heat.”
A growing number of U.S. cities – many of them ICLEI members – have adopted cool roof strategies, including Baltimore and Philadelphia. “It’s such a powerful tool to reduce temperatures inside of our buildings,” says Greco. “And my home city, New York, also has a cool roofs ordinance,” whereby the city mandates that most new roofs have 75% of the surface covered with a reflective white coating.
Yet another long-term solution to heat islands that has won considerable attention from the mainstream media is to regreen cities after years of doing the opposite. But such measures as green corridors or green belts “take time for the tree to grow,” says Greco. “Which means the time to start on this is now.” When done at scale she says “it can have a high impact” on how cities mitigate heat “with many co-benefits. Besides making people who are walking or biking feel cooler, it has also been shown that exposure to green spaces makes people feel better. And that’s good for our health and well-being.”
Mark Douglas Wessel is an Urban Journalist focused on sharing stories about people, places and initiatives that intend to create healthier, more livable communities.