The urban heat island effect describes how the spatial configuration of cities, the materials in them (such as asphalt), lack of vegetation and waste heat can modify temperature. Structures such as buildings, roads, and other infrastructure absorb and re-emit the sun’s heat more than natural landscapes such as forests and water bodies. There are a lot of factors we need to consider in the future and how to build future cities.”August 15, 2020 — Members of the Ocean Memory Project | Discover world-changing science. Heat Island Effect Heat islands are urbanized areas that experience higher temperatures than outlying areas. Research suggests that the phenomenon is broadly the result of less evapotranspiration—that’s when water evaporates from plants or soil into the atmosphere, cooling the air—in cities, compared with their surrounding environments. This effect increases energy costs (e.g., for air conditioning), air pollution levels, and heat-related illness and mortality. In general, he says the influence of heat waves in cities is probably a bigger challenge than the urban heat island effect. Daytime temperatures in urban areas are about 1–7°F higher than temperatures in outlying areas and nighttime temperatures are about 2-5°F higher. An official website of the United States government.Learn how you can reduce the urban heat island effect in Heat islands are urbanized areas that experience higher temperatures than outlying areas. But there isn’t a one-size-fits-all approach, and not every solution is appropriate for every city.Green spaces, for instance, can be a challenge to maintain in water-scarce areas. Australians now living in urban areas. "Urban heat islands" occur when cities replace natural land cover with dense concentrations of pavement, buildings, and other surfaces that absorb and retain heat. The effect needs to be factored into adaptation strategies, which will differ from city to cityIf you take a trip from rural Virginia into Washington, D.C., you may notice a change in atmosphere—literally.Scientists say the “urban heat island” effect, which can raise temperatures in cities by several degrees compared with their surroundings, could be a risk to human health as growing urban populations exacerbate the heating effects of climate change.The study suggests that, on average globally, urban heat island warming will probably be equivalent to about half the warming caused by climate change by the year 2050. But they may be a big concern in some regions.In particular, the authors point to cities in temperate and tropical parts of the global south, including parts of Latin America, Africa and South Asia, where absolute temperatures tend to be higher and where many nations have smaller economies and more difficulties adapting to the warming climate. Heat waves are becoming more frequent, more intense and a bigger risk to human health, he pointed out.
Unfortunately, the urban heat island effect affects nighttime temperatures the most: that’s when all the heat absorbed by the roads and buildings is re-released. The economic costs of a warming urban planet will be two and a half times worse thanks to the heat island effect, which concentrates hot air over densely populated areas. Find more information on the Low-income and minority neighborhoods can get significantly warmer than their surrounding areas due to the urban heat island effect. The researchers estimate that about half the world’s urban population will live in these regions by 2050.There are a variety of ways urban planners can attempt to lower city temperatures, Huang noted—creating more green spaces or building reflective rooftops that beam sunlight away. In a city that experiences 2 degrees of warming from climate change, for instance, that would mean an extra degree of warming.In some locations, the study warns, the effect could be twice as strong as the impact of global warming.According to lead study author Kangning Huang, a doctoral student at Yale University, the urban heat island effect isn’t included in the regional warming projections produced by the Intergovernmental Panel on Climate Change. And in colder climates, reflective surfaces may make temperatures more bearable in the summer, but can also make for even colder winters, increasing the amount of energy that residents use for heat.Sometimes there are trade-offs to consider when it comes to fighting climate change and fighting urban heat, Huang added. “I think my point is that the issue is more complicated than just about increasing density and increasing green space. Explore our digital archive back to 1845, including articles by more than 150 Nobel Prize winners.© 2020 Scientific American, a Division of Springer Nature America, Inc.Support our award-winning coverage of advances in science & technology.Subscribers get more award-winning coverage of advances in science & technology.Scientific American is part of Springer Nature, which owns or has commercial relations with thousands of scientific publications (many of them can be found at