The Value of US Urban Tree Cover for Reducing Heat-Related Health Impacts and Electricity Consumption
High air temperatures are a public health threat, causing 1300 deaths annually in the United States (US) along with heat-related morbidity and increased electricity consumption for air-conditioning (AC). Increasing tree canopy cover has been proposed as one way to reduce urban air temperatures. Here, we assemble tree cover and developed land-cover information for 97 US cities, housing 59 million people, and use regression relationships to analyze how much current urban tree cover reduces summer (JJA) air temperatures and associated heat-related mortality, morbidity, and electricity consumption. We find that 78% of urban dwellers are in neighborhoods with less than 20% tree cover. Some 15.0 million people (25% of total) experience a reduction of 0.5–1.0°C from tree cover, with another 7.9 million (13% of total) experiencing a reduction of greater than 1.0°C. Current relationships between temperature and health outcomes imply that urban tree cover helps avoid 245–346 deaths annually. Heat–mortality relationships in the 1980s, when a smaller fraction of US households had AC, imply a greater role in the past for urban tree cover in avoiding heat-related mortality. As AC availability has increased, the value of tree cover for avoiding heat-related mortality has decreased, while the value of tree cover for reducing electricity consumption likely has increased. Currently, for the 97 cities studied, the total annual economic value of avoided mortality, morbidity, and electricity consumption is an estimated $1.3–2.9 billion, or $21–49 annually per capita. Applying our results to the entire US urban population, we estimate urban tree cover annually supplies heat-reduction services worth $5.3–12.1 billion.
Keywordsair temperature energy use heat waves morbidity mortality United States
The authors thank their institutions for research support during the writing of this paper. RIM and TK were supported by a grant from the China Global Conservation Fund. PH thanks the Marianne and Marcus Wallenberg Foundation for their financial support. We also thank those who created the datasets used in this paper, including the NLCD, WUI, and the Global Historical Climatology Network. Without their data, our analysis would not have been possible.
- Association American Public Works. 2007. Urban forestry best management practices for public works managers: budgeting and funding. Washington, DC: American Public Works Association.Google Scholar
- Berko J, Ingram DD, Saha S, Parker JD. 2014. Deaths attributed to heat, cold, and other weather events in the United States, 2006-2010. National Health Statistics Report 76:1–15.Google Scholar
- EIA. 2015. Residential Energy Consumption Survey. Washington, DC. Available online at https://www.eia.gov/consumption/residential/data/2015/#ac.: US Energy Information Administration. Accessed December 2017.
- EIA. 2016. Electric Sales, Revenue, and Average Price. Washington, DC. Online at https://www.eia.gov/electricity/sales_revenue_price/. US Energy Information Administration. Accessed December 2017.
- EPA. 2014. Reducing Urban Heat Islands: Compendium of Strategies (draft). Washington, DC: Environmental Protection Agency.Google Scholar
- Hales S, Kovats S, Lloyd S, Campbell-Lendrum D. 2014. Quantitiative risk assessment of the effects of climate change on selected causes of death, 2030 s and 2050s. Geneva: World Health Organization.Google Scholar
- Homer C, Dewitz J, Yang L, Jin S, Danielson P, Xian G, Coulston J, Herold N, Wickham J, Megown K. 2015. Completion of the 2011 National Land Cover Database for the conterminous United States–representing a decade of land cover change information. Photogrammetric Engineering & Remote Sensing 81:345–54.Google Scholar
- IMF. 2017. World economic outlook database. Washington, DC: International Monetary Fund.Google Scholar
- Jenerette GD, Harlan SL, Buyantuev A, Stefanov WL, Declet-Barreto J, Ruddell BL, Myint SW, Kaplan S, Li X. 2016. Micro-scale urban surface temperatures are related to land-cover features and residential heat related health impacts in Phoenix, AZ USA. Landscape Ecology 31:745–60.CrossRefGoogle Scholar
- Kochanek K, Murphy S, Xu J, Tejada-Vera B. 2016. Deaths: final data for 2014. National Vital Statistics Report. 65.Google Scholar
- Matthies F, Bickler G, Marin N, Hales S. 2008. Heat-health action plans. Copenhagen: WHO Regional Office for Europe.Google Scholar
- McDonald RI, Aljabar L, Aubuchon C, Birnbaum H, Chandler C, Toomey W, Daley J, Jimenez W, Trieschman E, Paque J, Zeiper M. 2017. Funding trees for health: An analysis of finance and policy actions to enable tree planting for public health. Washington, DC: The Nature Conservancy.Google Scholar
- McDonald RI, Kroeger T, Boucher T, Wang L, Salem R. 2016. Planting healthy air: a global analysis of the role of urban trees in addressing particulate matter pollution and extreme heat. Arlington, VA: The Nature Conservancy.Google Scholar
- McMichael A, Campbell-Lendrum D, Kovats S, Edwards S, Wilkinson P, Wilson T, Nicholls R, Hales S, Tanser F, Le Sueur D, Schlesinger M, Andronova N. 2004. Global Climate Change. In: Ezzati M, Lopez AD, Rodgers A, Murray C, Eds. Comparative quantification of health risks: global and regional burden of disease attributable to selected major risk factors. Geneva: World Health Organization. Google Scholar
- McPherson EG, van Doorn N, de Goede J. 2015. The State of California’s Street Trees. Davis, CA: Pacific Southwest Research Station, U.S. Forest Service.Google Scholar
- McPherson G, Simpson JR, Peper PJ, Maco SE, Xiao QF. 2005. Municipal forest benefits and costs in five US cities. Journal of Forestry 103:411–16.Google Scholar
- NOAA. 2017. Global Historical Climatology Network. Administration NOaA editor. Online at: https://www.ncdc.noaa.gov/data-access/land-based-station-data/land-based-datasets/global-historical-climatology-network-ghcn. Accessed October 2017.
- OECD/IEA. 2018. The future of cooling: opportunities for energy-efficient air conditioning. https://webstore.iea.org/the-future-of-cooling: International Energy Agency (IEA).
- Oke TR. 1982. The energetic basis of the urban Heat Island. Quarterly Journal of the Royal Meteorological Society 108:1–24.Google Scholar
- Radeloff VC. 2010. 2010 Wildland urban interface (WUI) dataset. http://silvis.forest.wisc.edu/maps/wui/2010/download. Accessed October 2017.
- Taylor J. 1996. An introduction to error analysis: the study of uncertainties in physical measurements. Herndon, VA, USA: University Science Books.Google Scholar
- Vogt J, Hauer RJ, Fischer BC. 2015. The costs of maintaining and not maintaining the urban forest: a review of the urban forestry and arboriculture literature. Arboriculture & Urban Forestry 41:293–323.Google Scholar
- Zhang P, Bounoua L, Imhoff M, Wolfe R, Thome K. 2014. Comparison of MODIS land surface temperature and air temperature over the continental USA meteorological stations. Canadian Journal of Remote Sensing 40:110–22.Google Scholar