urban_heat_islands

Urban Heat Islands are concentrated areas of heat in urban and industrial areas lacking greenery. They are caused by reduced natural landscape and the properties of urban material and infrastructure. Urban heat islands increase energy consumption and contribute to climate change by increasing greenhouse gas emissions. They also highlight social inequalities as underfunded and underrepresented neighborhoods are more affected. Solutions include planting more trees, using green or cool roofs, and implementing urban forestry programs and green building design guidelines. Hello, and welcome to Urban Heat Islands. What are they, where are they, and how can I stop them? I'm your host, Caroline Fitzpatrick, a sophomore at Macalester College in St. Paul, Minnesota. Here in the Twin Cities, Minneapolis, and St. Paul, we have both harsh winters and summers. As summer is approaching, I would like to draw your attention to the incoming phenomenon that will take place soon here in the Twin Cities called Urban Heat Islands. In today's podcast, I will outline what Urban Heat Islands are, what causes them from a biophysical standpoint, their relationship with climate change, the social inequalities of urban heat islands, and to conclude, I will propose some solutions to eliminate or reduce the effects of Urban Heat Islands. What are Urban Heat Islands? Urban Heat Islands are concentrated areas of heat in the surface of, and the atmosphere just above, urban and industrial areas lacking any greenery. These dense areas of buildings, roads, and other infrastructure absorb the sun's heat more than the surrounding natural landscapes. According to the Environmental Protection Agency, or the EPA, heat islands can form under a variety of conditions, including during the day or at night, in small or large cities, in suburban areas, in northern or southern climates, and in any season. Temperatures within a city can drastically vary, creating what's known as an inter-urban heat island, or an even smaller area-wise heat island in an urban area. Urban heat islands are broken down into two characteristics, surface and atmospheric. Urban heat islands in the surface manifest in infrastructure, and they absorb and emit more heat than surrounding natural surfaces. In atmospheric heat islands, the less intense of the two characteristics of heat islands are formed by warmer air compared to the cooler air in outlying areas. What's their biophysical cause? Biophysically, urban heat islands are caused by reduced natural landscape and the properties of urban material and infrastructure. Natural landscapes are composed of greenery like plants, trees, and shrubs, and undergo processes like transpiration and evaporation that cool the air. In cities, skyscrapers replace trees and therefore destroy the natural environment. This means that natural plant-produced processes that cool the air are largely non-existent in many urban areas. Besides the reduction in the natural landscape, the materials used to create urban infrastructure also contribute to creating urban heat islands. Pavement and roofing reflects less solar energy compared to trees, vegetation, and other surfaces. Urban surfaces also absorb and emit more of the sun's heat relative to natural surfaces. Additionally, weather and wind contribute to the formation of urban heat islands. Calm and clear weather results in more severe heat islands by maximizing the amount of solar energy reaching urban surfaces and minimizing the amount that can be carried away. Wind flow, which is blocked by buildings in urban areas, creates a natural cooling effect. There are a multitude of environmental factors that contribute to the creation of urban heat islands, and human activity also has direct impacts. According to the EPA, anthropogenic causes like vehicles, air conditioning units, buildings, and industrial facilities emit heat into the urban environment. How do urban heat islands relate to climate change? Moving on from biophysical causes of urban heat islands, let's now take a look at how this phenomenon relates to climate change. Urban heat islands increase energy consumption by increasing the demand for air conditioning. Increased energy leads to more greenhouse gas emissions because electricity is reliant on fossil fuel power plants. More greenhouse gas emissions means more ground level ozone, or smog, fine particles in the atmosphere, acid rain, and generally more carbon dioxide emissions. Besides elevated emissions of air pollutants and greenhouse gases, urban heat islands also contribute to impaired water quality. High temperatures of pavement and rooftop surfaces can heat up stormwater runoff, which drains into storm sewers and raises water temperature as it releases into streams, rivers, lakes, and ponds. This negatively affects aquatic species as warm water temperatures harm their metabolism and reproduction. How do urban heat islands highlight social inequalities? Urban heat islands also compromise human health, especially the health of underfunded and underrepresented neighborhoods. Health-related deaths and illnesses like respiratory difficulties, heat cramps, heat exhaustion, and heat stroke are all possible effects of urban heat islands. According to the EPA, people of color and community members with low incomes are more likely than other groups to live in historically redlined neighborhoods that are present-day intra-urban heat islands. It is important when looking at urban heat islands to discuss how they highlight social inequalities. An EPA review of several studies found that some communities in the United States, particularly those that are low-income and with higher populations of people of color, have neighborhoods with higher temperatures relative to adjacent neighborhoods in the same city. Racist policies enacted in the early stages of America and in the creation of the city have powerful consequences to this day. Privilege greatly affects how closely we see and feel the effects of urban heat islands. What are some solutions? To conclude today's podcast, I want to shine a light on some solutions to fight against urban heat islands. First of all, planting more trees and growing more vegetation in urban areas lowers surface and air temperatures by providing shade and cooling through evapotranspiration. They also reduce stormwater runoff and protect against erosion. Best of all, they tend to be easy to plant and oftentimes with minimal upkeep. This makes planting more vegetation a viable option to help reduce the effects of urban heat islands. In addition, changing the materials used to build or layer the surface of urban areas can help the cause. Green roofs or cool roofs are made of plants or minerals that reflect sunlight and heat away from buildings. Green roofs and urban greenery in general can improve stormwater management too. On a local, municipal, and national level, we must take action to draw attention to urban heat islands and reduce or eliminate them. Urban forestry programs locally and green building design guidelines more largely both contribute to the same goal of ending urban heat islands. Thank you for listening to my podcast and to find more ways to get inspired, go to www.epa.gov backslash heat islands backslash what communities are doing to reduce heat islands. Thank you.