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Heat Islands

Heat Island Newsroom

Welcome to EPA's Heat Island Newsroom, which includes recent issues of the Heat Island Newsletter and other notable news items. Older newsletters can be found in the Newsroom Archive. To receive the newsletter and notices of heat island-related conferences by email, sign up for EPA's Heat Island Newsletter.

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February 13, 2018 Newsletter

Heat Islands

  • Urban Heat Island Effect Projected to Strengthen – In the recently released Fourth National Climate Assessment, Volume 1: Climate Change Special Report, the U.S. Global Change Research Program (USGCRP) reports for the first time a key finding that the heat island effect is responsible for higher daytime and nighttime temperatures in urban areas compared to surrounding rural areas. USGCRP projects with high confidence that the heat island effect will strengthen in the future as urban areas change and grow, and population densities increase. The report is an assessment of a large body of scientific, peer-reviewed research and is regarded as an authoritative resource on the science of climate change in the United States.
  • Vulnerable Populations and Phoenix’s Widening Heat Island – Across the U.S., urban heat puts vulnerable populations, like low-income, homeless, and elderly individuals, at higher risk of heat-related illnesses and even death. Accordingly, in Phoenix, Arizona, differences in exposure, sensitivity, and adaptation to high temperatures lead to disparate effects on the city’s residents. A range of tactics are being employed by the City of Phoenix to fight the heat and improve the health of residents: painting roofs with reflective paint, planning more trees, and implementing the “We’re Cool” program, which provides free centers for cooling off and hydrating.

Green Infrastructure

  • How to Fund Your Green Infrastructure Project – The National Recreation and Park Association published a new guide to financing green infrastructure projects. The guide includes strategies like partnering with nontraditional supporters, and folding green infrastructure projects into financing for stormwater projects. Heat island mitigation strategies to install green roofs and plant trees and vegetation are types of green infrastructure; the funding strategies in the guide could be used to advance heat island reduction projects.

Green Roofs

  • Denver Passes Green Roof Ballot Initiative – In November 2017, Denver, Colorado voters approved a modification to the city building code requiring rooftops of new buildings over 25,000 square feet to include green roofing or solar panels, with the goal of mitigating urban heat. The green roof/solar requirement increases 10 percent for every 50,000 square feet, up to a cap of 60 percent.

Cool Roofs

  • Heat Mitigation Conserves Water, Too – A study from Lawrence Berkeley National Laboratory (LBNL) found that widespread implementation of cool roofs – made of materials or coatings that reflect heat and sunlight – in California would result in cooler temperatures and also reduce outdoor water consumption. The study showed that by contributing to lower air temperatures, cool roofs reduced evaporative transpiration and evaporative water demand, therefore reducing irrigation water use.

Cool Pavements

  • Los Angeles is Coating its Streets to Fight Urban Heat – Los Angeles, California, is piloting ways to combat rising temperatures and reduce the heat island effect, including coating city streets with CoolSeal, a substance designed to reflect solar radiation. City officials linked cooler streets to cooler air temperatures, reduced air conditioning use, and decreased heat-related deaths.
  • Cost-Effectiveness of Cool Surfaces – Many cities are coating or building walls and pavements with reflective materials, but how cost-effective are these methods for heat mitigation? A study from LBNL’s Heat Island Group describes methods for quantifying some of the benefits of cooler surfaces, such as reduction in electrical energy usage and avoided carbon dioxide emissions.

Trees and Vegetation

  • Urban Forests in Canada Reduce Air Pollution and Improve Public Health – In addition to cooling air temperatures and sequestering carbon, urban trees can clean the air when particulate pollutants adhere to their surfaces and gaseous pollutants are taken up through leaves. A study from the U.S. Forest Service and Environment Climate Change Canada found that trees in 86 Canadian cities removed thousands of tons of air pollution, leading to positive human health outcomes including reduced mortality and prevention of acute respiratory symptoms.
  • Investing in Urban Trees Benefits Public Health – Trees provide a variety of ecosystem services such as heat mitigation, air purification, and recreation and tourism benefits. These advantages also result in public health and economic benefits that may not be fully understood by city planners and policy makers. A 2017 report by The Nature Conservancy provides information on the links between the health benefits of urban trees, and the finance and policy solutions cities can use to realize these benefits. For example, the authors used the EPA's CO-Benefits Risk Assessment Health Impacts Screening and Mapping Tool (COBRA) to estimate that 27 cities could each avoid $13.2 million per year in health care costs from urban tree planting.

Public Health

  • New Risk Mapping and Planning Tool – The New Orleans Office of Resilience and Sustainability and the Trust for Public Land launched a new mapping tool designed to identify priority areas for investments in green infrastructure in New Orleans, Louisiana, based on a suite of considerations such as heat mitigation and social equity. Through a partnership with the Louisiana Public Health Institute, the tool incorporates neighborhood level data for 15 health outcomes, including cardiovascular disease, respiratory disease, diabetes, and stroke. This tool was presented at the 2017 American Public Health Association meeting.