For urban cooling, forests beat street trees, landscaped parks: study

Healthy Urban Forests Provide More Cooling Benefits than Other Green Spaces, Study Finds

Dive Brief:

• Healthy urban forests that look and feel like the wilderness provide more cooling benefits than other green spaces, such as landscaped parks and street trees, according to a study released by the New York City-based Natural Areas Conservancy.
• The study, conducted last summer in 12 U.S. cities, finds that on a hot summer day in some cities, the temperature in these urban forests was as much as 10 degrees F cooler than under street trees a few hundred feet away.
• The findings indicate that cities should allocate more resources to caring for urban forests. Natural areas should also be part of cities’ plans to address urban heat islands, alongside more common practices such as street-tree planting, green roofs, and building materials innovation.

Dive Insight:

Urban trees have gotten a good bit of attention – and funding – lately, from everyone from President Joe Biden to Amazon founder Jeff Bezos. The benefits of trees in cities, including their ability to cool neighborhoods, are well-documented. If anything, the urgency to expand urban green spaces in cities has only grown after a summer plagued by extreme heat, which experts say will likely be part of the new normal as climate change worsens.

But as city leaders work to fulfill their promises to increase tree canopy, certain questions remain. For example, do different types of green spaces provide different cooling benefits? The Natural Areas Conservancy set out last summer to answer that question.

The study is based on land-temperature data from satellites and air-temperature data from sensors placed on trees in Seattle; Minneapolis-St. Paul; New York; Baltimore; Chicago; Miami; Houston; St. Louis; Indianapolis; Billings, Montana; Austin, Texas; and Tampa-Hillsborough County, Florida. These 12 urban areas are all part of the Forests in Cities network, a national coalition of urban forest professionals.

Forested natural areas – characterized by multiple layers of plants and trees of different ages – were 3 to 9 degrees F lower than the average citywide temperature, depending on forest and city type. The coolest type of forest was conifer, with the only studied example Seattle. Forests with wetter conditions, such as forested wetlands and mangrove forests, were also particularly cool.

Landscaped areas, such as bare soil, lawns, and street trees, generally had less cooling benefits. In Billings, for example, a forest was over 14 degrees F cooler than a landscaped location at 6 p.m. on Sept. 3, 2022.

Healthy forests were generally cooler than degraded forests during the afternoon, with less temperature variation throughout the day.

“Understanding the relationship between forest condition and cooling impacts is important,” the study says. “Urban forests face many threats including fragmentation and increased pressures from problem species.”

Despite these benefits, the study said urban natural areas are “underfunded and unprotected, leaving them imperiled in cities across the country.” They may be viewed as “weedy” compared with landscaped parks and street trees; cities in the study allocated an average of 4% of park budgets to caring for forests, even though they make up a majority of city parkland.

“We view natural areas as a less well understood but critically important piece of the entire urban forest,” Natural Areas Conservancy Executive Director Sarah Charlop-Powers said Tuesday on the The Brian Lehrer Show. “We view this work as an important puzzle piece in solving the really large and thorny challenge of extreme heat in New York City and in cities across the country.”

SDGs, Targets, and Indicators

1. Which SDGs are addressed or connected to the issues highlighted in the article?

• SDG 11: Sustainable Cities and Communities
• SDG 13: Climate Action
• SDG 15: Life on Land

2. What specific targets under those SDGs can be identified based on the article’s content?

• SDG 11.7: By 2030, provide universal access to safe, inclusive, and accessible, green and public spaces, in particular for women and children, older persons, and persons with disabilities.
• SDG 13.1: Strengthen resilience and adaptive capacity to climate-related hazards and natural disasters in all countries.
• SDG 15.2: By 2020, promote the implementation of sustainable management of all types of forests, halt deforestation, restore degraded forests, and substantially increase afforestation and reforestation globally.

3. Are there any indicators mentioned or implied in the article that can be used to measure progress towards the identified targets?

Yes, the following indicators can be used to measure progress towards the identified targets:

• Temperature difference between urban forests and other green spaces (indicator for SDG 11.7)
• Temperature reduction in urban forests compared to street trees (indicator for SDG 13.1)
• Temperature variation throughout the day in healthy forests (indicator for SDG 15.2)

4. Table: SDGs, Targets, and Indicators

Behold! This splendid article springs forth from the wellspring of knowledge, shaped by a wondrous proprietary AI technology that delved into a vast ocean of data, illuminating the path towards the Sustainable Development Goals. Remember that all rights are reserved by SDG Investors LLC, empowering us to champion progress together.

Source: smartcitiesdive.com

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