Along a busy road in west Detroit, there’s little respite from the sun for residents getting gas, visiting houses of worship or taking children to day care. But a burgeoning canopy of trees planted this year will change the look of this corridor.
Detroit and other cities are adding trees and green spaces as a way to mitigate the impact of warmer average temperatures and heat waves that are longer and hotter due to climate change.
The United Nations is urging governments, institutions and investors to prioritize sustainable cooling solutions that do not further warm the planet, including planting trees for shade and using reflective building materials. The UN Environment Program and the International Finance Corporation released a report on financing these solutions for developing countries during meetings of the UN General Assembly on Wednesday.
It is the latest effort by the UN to help countries and cities cool buildings without adding air conditioners, raise energy efficiency standards for cooling equipment and phase out highly polluting refrigerants. The goal is to reduce emissions from cooling to almost zero by 2050.
“We are facing record-breaking temperatures. We need to save people from extreme heat,” said Lily Riahi, global coordinator of the UNEP-led Cool Coalition. “But we need to find a way to cool the planet in a way that doesn’t create more heat.”
Worldwide, 20% of electricity is used for cooling. If nothing changes, demand for equipment such as air conditioners and refrigerators is expected to triple by 2050, doubling electricity consumption and increasing fossil fuel emissions, UNEP said.
During last year’s UN climate talks, a Global Cooling Pledge was launched to reduce emissions from cooling. And Riahi says the United States, one of 71 countries endorsing it, is a leader in using nature for cooling to tackle extreme heat.
A historic investment in urban trees is currently underway. The US Forest Service Urban and Community Forestry Program received $1.5 billion in 2022 through the Inflation Reduction Act. Grant applications flooded in as heat records were broken in 2023. Nearly 400 projects were selected for funding.
The program normally receives about $40 million annually.
The cost of planting and maintenance is the biggest obstacle to most greening projects, says Daniel Metzger, a fellow at the Sabin Center for Climate Change Law. Where a project transforms previously paved space, removing asphalt or concrete is generally the largest expense, he said.
Urban areas are often hardest hit by the harmful health and environmental impacts of heat waves. Urban areas are warmer than surrounding suburbs – the ‘urban heat island’ effect – due to abundant heat-absorbing surfaces. Trees and vegetation provide shade and lower surface and air temperatures.
Increasing a city’s canopy by 10% reduces temperatures by 1.8 degrees Fahrenheit (1 degree Celsius), according to the Smart Surfaces Coalition. The coalition helps cities integrate cool roofs, green roofs, solar energy, porous paving and urban trees.
“We cannot solve this problem with air conditioning,” says coalition founder Greg Kats. “The way to solve this is citywide cooling.”
As Detroit grew, the city built tall, concrete buildings, industrial areas, commercial corridors and roads. What was once called a “city of trees” lost thousands of people. Some were cut down; others died from diseases and plagues.
Detroit received $3 million through the urban forestry program to increase tree canopy in neighborhoods with few trees.
Eric Jones, a resident of the Woodbridge neighborhood, said some homeowners don’t want trees because they think squirrels and falling leaves are a nuisance. For Jones, 47, cooling off in the summer is more important than when he walks or runs with his wife and daughter. Trees also improve air and water quality, help prevent stormwater runoff, capture carbon dioxide and can increase property values.
“On a day like today where it’s in the 80s or 90s and it’s sunny, I mean, it’s just amazing the difference we feel in our neighborhood compared to when we come outside and there’s not as many trees” , says Jones. said.
Crystal Perkins, Detroit’s general manager, said it will take some time to feel the citywide impact as immature trees need to grow. Detroit plans to plant 75,000 young trees in five years.
“We know we will reap the benefits for generations to come once we make these changes,” Perkins added.
Pastures can also help cool an area. Grasses and native plants can be a complementary approach to urban cooling because they reflect sunlight and absorb less heat than concrete or asphalt, says Lin Meng, assistant professor of earth and environmental sciences at Vanderbilt University.
A meadow planted in Detroit’s Palmer Park in 2020 has grown 6 feet tall, with blooming purple asters, yellow goldenrod and Black-eyed Susans.
The Forestry Program prioritized communities that have historically been “marginalized, underserved and overburdened by pollution” when choosing projects for grants. Secretary of Natural Resources and Environment Homer Wilkes said extreme heat disproportionately affects minority and low-income communities with few trees.
Researchers have found fewer tree canopies on average in communities inhabited primarily by racial and ethnic minorities in the 1930s, when financial services were withheld due to the discriminatory housing policy known as redlining. A 2021 study in NPJ Urban Sustainability of 37 U.S. cities found nearly twice as many tree canopy cover in predominantly white communities in the 1930s.
The rating system used to assess credit risk reflects today’s tree coverage, lead author Dexter Locke said in an interview.
“The lethality of urban heat may increase with a changing climate,” Locke said. “The people who are least able to cope cannot afford air conditioning. So there is a real double environmental injustice.”
In Baton Rouge, Louisiana, nonprofits are planting citrus trees around public housing. Backed by a $6 million grant from the U.S. Forest Service, two community groups are launching an apprenticeship program to teach dozens of young people how to plant and care for trees, expand urban tree canopy, combat food insecurity and raise environmental awareness to enlarge.
“That’s a landscape that’s changing on a massive scale for a zip code,” said Sage Roberts Foley, executive director of Baton Rouge Green.
Baton Roots mobile farm manager Jacquel Curry, 29, appreciates the citrus trees planted in his neighborhood because they provide shade, cooling that can lower electric bills and fresh fruit once they mature.
“The whole goal is to reverse the bad knock-on effects from the lack of trees,” Curry said. “We’re trying to get it to go the other way again.”
