The Negative Effects of Urban Heat Islands

Introduction

According to the Environmental Protection Agency defines sustainability as a simple principle: resources needed for survival from the natural environment used in a way in which nature and humans can exist harmoniously in order to support present and future generations. The sustainability can become threatened by urban heat islands due to them forcing citizens to expend energy, strain water sources, air pollutants, and destruction of trees.

Description of Target/Problem

Phoenix Arizona is a suburban city sprawled out in the upper edge of the Sonoran desert. The urban surface allows for the build up of an urban heat island, the concentration of heat on the specific urban setting. On average, heat islands occur on a hot day accumulating to the temperature of surfaces to be 50-90 F and nighttime low temperatures 10 to 15 degrees Fahrenheit warmer than that in rural areas. However, in comparison to other states, Arizona has one of the highest heat temperatures in the United States leading to an intense heat islands.

Phoenix’s intra urban temperature are caused by its clear skies and low wind speeds and, as a result of the city’s structure of narrower skyview factors, there is reduced radiative loss and heat retained. In addition, the cement and asphalt absorb the heat during the day to then gradually release the heat at night. Waste heat from air conditioning increases the temperature by 2F and contributes toward the Urban Heat Island effect causing heat to be stronger from the late afternoon to early morning.

One other minor cause of the Urban Heat Island effect is the political climate in Arizona. Many of the Arizona residents and political leaders are do not accept climate science and are resistant to any actions to fight global warming and in 2016, passed a law that prevents cities from requiring businesses to report how much energy they use.

Stakeholders

Many parties are stakeholders in the effects of urban heat islands but the largest and most vulnerable population being negatively impacted are families of lower socioeconomic income, which encompasses racial minorities, specifically the large African American and Latino population. They feel the full brunt of the urban heat island effect in both the high day and nighttime temperatures and the increased cost of maintaining air conditioning and water.

The general public of Phoenix has to bear the costs of air conditioning as it becomes a necessity. Additionally, Phoenix resident’s taxpayer money is forced to go toward the continually increasing heat mitigation actions. The urban heat island directly impacts the homeless population of Phoenix in the rise of heat related deaths and illnesses.

Who is Harming?

The main contributor to the urban heat island effect is the City of Phoenix but specifically the urban planning and development department who control the location of structure, land use, and safety. Other contributors are both Salt River Water Project Power and Water and the Palo Verde Nuclear Generating Station who benefit from the increased profit in that they both become essential to living comfortability in Phoenix.

Economic

Urban Heat Island effect in Phoenix have led to an increase in cooling degree days which is the amount of artificial cooling needed to maintain a comfortable indoor temperature. There has been a steep increase in cooling days as the years have continued. As the amount needed to cool down households increase, the cost of the electricity bills. This impacts the public of Phoenix due to the need to cool down households becoming a vitality. The increase in the number of cooling days represents the increase in the number of days above 65F or an increase in the number of degree above 65F. The increase in cooling degree days since 1970 for Phoenix, Arizona is 1,080, which results in an increase in the cost of air conditioning.

The reduction parameters and excess cost for Phoenix Arizona is estimated to cost Phoenix $479 million based on the urban heat island magnitude. This will impact the Phoenix taxpayers’ money. The economic impact is measured as a percentage of regional GDP. The automotive excess total cost is $43 million dollars with a 3°C or around 28.22 per working person per year. In addition, there is also the cost of the air conditioning and maintenance at $76 per household with the added cost of maintenance $11. Shown in figure 3 is a table displaying the amount annually of mitigating urban heat island effects for Phoenix Arizona.

Social

Those from a lower socioeconomic income suffer, specifically minorities such as African American and Latino, as a result of them living in the outskirts of the city where there is little shade and vegetation, close to industrial areas, commercial places, transportation corridors and little initiative to reduce the urban heat island effects.

In addition, this population will struggle to maintain efficient cooling measures as the need for air conditioning increases along with the price to accommodate. Although this is detrimental to lower income families, producers of the energy will benefit such as the Salt River Water Project Power and Water. This can be seen in an increase of 1°C temperatures and is estimated to cost each household $76 per year with an excess of $11 per year for repair costs. Air conditioning costs hurts the people who are in need of it the most.

Families and households living within the urban heat island or experience a rise in temperature will be hit with an increase in water usage. Those that will benefit are the water suppliers in Phoenix, Arizona- City of Phoenix Water and Central Arizona Project. It is predicted that an increase in 1°F temperatures will increase average water use in single-family units by 1.7% or 290 gallons for a typical single family unit in the month of June.

If there were a 5°F increase in the temperatures would raise water usage by 9% or 1,532 gallons in one month for an average single family home. The population that is often overlooked yet is most directly impacted is the homeless population living in Phoenix. Within the homeless population, it is specifically white, males between the age of 50 to 64 years of age. The number of heat related deaths are recorded in the Maricopa Government archives and display that the majority of the heat related deaths were within Maricopa County as opposed to outside county. Heat related deaths from 2015 to 2016 have increased by 48% and it specifically targets males, around the age of 75 and older.

Environmental

In accordance to the increase in energy usage by the residents being affected by the urban heat island, the demand for energy due to air conditioning become increased as well. The environment becomes negatively impacted as harmful chemicals are released into the atmosphere and the rate at which they are being released becomes accelerated because the demand is higher.

An Arizona household uses 66 million btu of energy per home which is 26% less than the US average. According to the Environmental Protection Agency, electricity demand for cooling increases 1.5-2.0% for every 1F increase in air temperatures, from 68F to 77F. Arizona gets one fourth of its energy from Palo Verde Nuclear Generating Station as well as the Navajo Generating Station, coal-fired power plant.

Although nuclear plants do not release much waste but the waste is radioactive and becomes more difficult to safely remove and also the mining of uranium. From the Nuclear Generating Stations, waste ends up as fly ash, bottom ash, and boiler slag. Only 80 to 90% of the ash and slag are non-radioactive and contain silicon, aluminium, iron, and calcium.

The urban heat island effect impacts the amount of water needed to maintain vitality in the high temperatures. Phoenix already has a limited amount of water. Measures to reduce the urban heat island effect include drinking large amounts of water as well as watering plants and vegetation which can mitigate the effect.

Water source, the Salt and Verde River watersheds, are already threatened by the high rates of growth an uneven precipitation so water is already depleted. The City of Phoenix’s water consumption is 140 million gallons per day in the peak summer months. Families use ¾ or 50% of the demand. The Water Research Foundation detailed that the single-family residents used approximately 44,000 to 175,000 gallons of water per unit.

Due to elevated low temperatures, there was a higher demand of water towards the northeast and north of Phoenix city center at 21, 578 gallons per month, which were the top 10%. In comparison, the lower 10% used 11,515 gallons per month.