Science Policy

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A National Framework for Sustainable Urban Forestry to Combat Extreme Heat

04.04.24 | 7 min read | Text by Arnab Ghosh

Extreme heat events are increasing in frequency and intensity every year, leading to devastating human costs such as hospitalization and death. In urban environments, where over 80% of Americans live, these effects are exacerbated by the urban heat island effect. In alignment with the White House’s nature-based solutions efforts to address the effects of climate change, the role of greening has been touted as a life-saving means to protect urban residents from extreme heat, mitigate stormwater, and reduce air pollution. Nonetheless, the benefits of urban forestry have not yet been realized due to unsustainable funding at municipal levels for maintenance and stewardship, limited coordination across branches of government, inequitable distribution of trees, and a lack of analyses that define the economic value of urban forestry. A coordinated, equity-focused, and economically validated federal plan to guide the development and maintenance of urban forestry will allow the full utilization of this critical resource. Achieving this goal requires action at all levels of government; sustainable funding to grow, develop, research, and sustain urban forests; and ongoing leadership from the scientific and forestry communities.

The incoming administration should undertake a multi-agency effort to further develop the science and quantify the benefits of urban forests today and into the future. This will equip urban foresters and their municipal partners with the necessary decision support tools to plant, grow, and maintain urban forests in cities across the United States. Doing this will ensure current forestry investments created by the Inflation Reduction Act (IRA) and Bipartisan Infrastructure Law (BIL) continue to reap maximum benefits into the future. By using environmental economic principles in national accounts and leveraging the Office of Management and Budget’s (OMB) new Ecosystems Services Guidance to capture the true value of urban forests and their ecosystem services to the U.S., the federal government will provide the economic basis for further strategic planning of urban forestry. Additionally, applying the principles of environmental justice ensures decisions will support efforts to overcome the histories of redlining that prevented the expansion of urban forests into disadvantaged neighborhoods. Undertaking these efforts can lead to the realization of the potential benefits of urban forests, estimated conservatively to be over $17 billion annually. 

Challenge and Opportunity

Every year, extreme heat events are increasingly threatening to human health. Recent summers have seen rises in heat-related hospitalizations. In 2023, heat-related hospitalizations increased by 51% compared to 2018. However, federal, state, and local governments are limited in their approaches to addressing extreme heat’s effect on human health and well-being. Public health approaches to tackling this growing problem include the development of coordinated messaging between public health, health systems, and community members to warn of impending extreme events, cooling centers, and the distribution of air conditioner units. Unfortunately, these prevention strategies are often reactive and unsustainable in the long term. They rely on forecasting of extreme heat events to initiate alerts or to establish cooling centers and increase demand for air conditioning, which drives up energy costs and greenhouse gas emissions.

An alternate, longer-term, and more effective strategy is to use trees as a form of natural infrastructure, particularly where the urban heat island effect takes place (i.e., the sustained increased temperatures during the day and night due to heat retention from the built environment). Trees can reduce air temperatures by up to 10ºF, and surface temperatures up to 25ºF. Urban forestry impacts over 80% of Americans, where the urban heat island effect is most pronounced. Although not accounted for in today’s macroeconomic evaluations of gross domestic product, the U.S. Department of Agriculture (USDA) Forest Service estimates that urban forestry currently provides over $17 billion in ecosystem service benefits annually through improvements in air quality, stormwater management, improved physical and mental health, and increased property values. Moreover, urban forestry is cost-effective: for every $1 spent on urban tree management, benefits are estimated to be valued at $1.37 to $3.09. Urban forests, when strategically planted or naturally regenerated and maintained, also have the potential to be a long-term, sustainable, nature-based solution to the rising threat of extreme heat on human health.

The USDA US Forest Service is rapidly expanding tree inventories across the nation, informed by the Ten-Year Urban Forestry Action Plan created by the National Urban and Community Forestry Advisory Council (NUCFAC). Funds for urban forestry have recently been appropriated through the IRA and BIL, which allocated over $1 billion over the next five years to urban forestry. Strategically channeling these funds through federal oversight and technical assistance to address the rising threat of extreme heat will provide the best opportunity to maximize the use of these funds and demonstrate the outcomes of sustaining federal investment at that scale. 

Therefore, to reduce extreme heat in urban areas where most Americans live, a comprehensive urban forestry strategy is essential. This strategy should provide ongoing support within and across cities, and link the science of tree selection, climate-resilient seed propagation, planting, and maintenance with efforts to overcome disparities in urban greening infrastructure. Further, there is an ongoing need to develop the urban forestry workforce and capacity necessary to sustain these investments and ensure their benefits come to fruition. Finally, ongoing research and analysis is needed (anticipated at $50 million annually by NUCFAC) to inform urban and community forestry policy and increase the effectiveness and benefits of greening interventions.

Plan of Action

Creating a strategic plan for urban forestry management to combat extreme heat requires equity-centered coordination across various federal agencies, given the clear disparities in urban greening infrastructure within and across U.S. cities. The strategy must also further the development of research to maximize ecosystem services, incorporating the costs of urban forests over extended periods. 

Thus, the federal plan of action must be guided by the following principles:

1. Placing environmental justice and equitable urban greening practices at the forefront of a strategic plan.
2. Employing natural capital cost assessments — a key endeavor of the Biden Administration to include environmental-economic appraisal of nature-based solutions — in the development of the potential of public-private partnerships (e.g., US Forest Service Public-Private Partnership Strategy).
3. Specifying cross-agency collaboration to directly quantify the benefits from a diverse range of perspectives. For example, direct healthcare benefits from urban forestry require long-term and causal research on the quantity, distribution, and duration to account for such benefits from an environmental-economic perspective.

Coordinate the Executive Branch. A federal interagency task force consisting of urban forestry experts, healthcare authorities, economic stewards, and heat science specialists should lead the effort to create a national urban forestry strategic plan. This taskforce should be co-led by OMB and the Council on Environmental Quality (CEQ) and should include the following agencies: the USDA Forest Service, Department of the Interior (DOI), Centers for Disease Control and Prevention (CDC), National Institutes of Health (NIH), Department of Commerce Bureau of Economic Analysis, Housing and Urban Development (HUD), Department of Transportation (DOT), the National Oceanic and Atmospheric Agency (NOAA), and other agencies as relevant. The following courses of action should be taken:

• Direct studies to evaluate and directly quantify the ecosystem services and disservices of urban forestry under current and future climate scenarios.
• Dedicate resources to expeditiously create a national inventory of urban forests, indexed by location, species, and age.
• Direct agencies to build methodologies as a first case study to detail how natural capital assessments for nature-based solutions can be undertaken.
• Build a strategic plan for tree planting and maintenance by climate region and city type, including the development of decision support tools for state and city-wide urban foresters to best allocate resources.
• Undertake evaluative work to direct already appropriated funds through the IRA and BIL to urban forestry projects with the highest benefit to communities locally and regionally.

Strengthen the Evidence Base. Empirical data to inform natural capital assessments and the beneficial and detrimental effects on heat mitigation and stormwater mitigation will be required to better analyze and build policies. Areas in need of development include: human health benefits and healthcare return on investment; climate and resilience, especially around forest vulnerabilities; and environmental justice, including lowering the burden of ongoing maintenance on communities. Through the NIH, CDC, National Science Foundation (NSF), Department of Energy (DOE), Environmental Protection Agency (EPA), USDA, NOAA, and National Aeronautics and Space Administration (NASA), funding should be allocated to:

• Undertake studies to quantify and evaluate health-related ecosystem services and disservices of urban forestry under various climate scenarios in the short and long term (NIH, CDC, USDA).
• Quantify the correlation between increased greening and lower air temperatures, reductions in energy demand, benefits to energy efficiency of buildings and homes, and decreases in greenhouse gas emissions (EPA, DOE, NOAA, NASA, USDA).
• Examine the differential impacts of urban forests according to the principles of environmental justice (NIH, USDA, EPA, NSF).
• Determine the future-proofing needs of urban forestry investments across the U.S.’s 12 climatic regions (USDA, NOAA, NASA).
• Reexamine existing correlative studies to determine underlying causation regarding urban forestry human health benefits and ecosystem impacts (CDC, NSF, EPA, USDA).
• Undertake implementation studies to ensure the feasibility, cost, and efficacy of an urban forest intervention to limit the effects of extreme heat on communities (USDA, NOAA, NIH, NASA).

Conclusion 

Extreme heat events are rising in intensity, frequency, and severity, particularly within cities. Existing measures to protect residents against the scourge of these events are limited while they need to be equity-focused, sustainable, and address the rising threat of climate change now and into the long term. The influx of investment in urban forestry from the IRA and BIL has provided the necessary foundation for the benefits of urban forestry as a source of nature-based solutions to combat extreme heat.

A federal strategic plan for urban forestry management to combat extreme heat is necessary to fully capture the benefits of this investment. By employing natural capital assessments, directing cross-agency collaboration, and building the necessary scientific evidence, urban forestry can serve as key infrastructure to create climate resilient communities across the United States.

This idea of merit originated from our Extreme Heat Ideas Challenge. Scientific and technical experts across disciplines worked with FAS to develop potential solutions in various realms: infrastructure and the built environment, workforce safety and development, public health, food security and resilience, emergency planning and response, and data indices. Review ideas to combat extreme heat here.