The Urban Heat Island Effect in Los Angeles by Ji Hyun Park and Ji Sun Park

In 2012, during the Creek Week program with Heal the Bay, my sister and I grew interested in the Los Angeles River and the environmental impacts of the concretion of the different sectors of the river. In the November of 2013, my sister and I researched five different sites along the Los Angeles River. These areas ranged from environmental healthy mountainous regions of the river to heavily urban-concreted areas. In conclusion to this yearlong study of the water quality of the multiple sites of the Los Angeles River, we were able to find that there was a temperature fluctuations between the two sites. The environmentally healthier areas had lower temperatures, while the urban areas of the river showed higher temperatures. This, we concluded, was the result of the Urban Heat Island effect. The Heat Island Effect is when an urban or metropolitan area is warmer than the surrounding areas.

For the last several decades, human population has shifted from rural areas to urbanized areas. This urbanization to metropolitan cities has led to a larger economy, higher convenience, and increased industry. Despite these positive impacts of urbanization, there have also been multiple negative impacts of the creation of Metropolitan cities. There has been increased heat production due to burning of fossil fuels and increased industrial and residential activities. Vegetation were reduced in order to make more room. There has also been increased heat absorbance in these Metropolitan cities as the building and paving materials absorb solar energy.

Urbanization has also shown environmental impacts. There are increases in energy consumption due to higher heat of the surrounding areas. This results in reduced air quality and increases in greenhouse gases, as power plants burn more fuel in order to cater to the energy needs of the public. This air pollution leads to acid rain and climate changes. The increased heat from urbanization can also result in health issues for humans.

All this results in what is called the Heat Island Effect. Los Angeles is definitely experiencing a Heat Island Effect. Due to this, residents of Los Angeles are suffering from health problems. There were hundreds of people who went to the emergency room due to heat-related illnesses from 2005-2010.

When compared to every city in the United States experiencing a Heat Island effect, Los Angeles is not the hottest city. However, it is notably the hottest city in the west as well as one of the cities that receives the lowest mean precipitation.

Los Angeles has taken initiatives to mitigate the Heat Island Effect. One of the ways is the use of CoolSeal to paint pavements and roads. CoolSeal is a special type of paint that reflects heat. Animals prefer walking on areas treated with CoolSeal rather than regular pavements; treated areas were 10 degrees cooler than untreated areas.

Other cities have also taken initiatives to mitigate this problem. One city initiative was the revitalization of Seoul’s Cheonggyecheon. Cheonggyecheon was a heavily polluted stream that ran in the heart of Seoul, South Korea. It was completely paved and a highway was built on top of it. The stream emitted a horrible stench and was home to millions of rats. In 2008, removing the highway rehabilitated the stream and concrete, planted greeneries, and made cold water flow properly.

The average surface temperatures of Seoul before and after the revitalization did not change. However, the average air temperature of Cheonggyecheon showed a startling drop of approximately one degree Celsius. The study showed that temperature decreased dramatically near the presence of flowing water for about fifty meters before temperature rose to the same height.

Los Angeles, like Seoul, has a river that flows in its heart. As our previous research on the LA River indicated, surface temperatures impact air temperatures. The sites with more vegetation had lower surface temperatures, resulting in cooler air temperatures, while built-up concreted areas of the river had higher surface temperatures, resulting in hotter air temperatures.

In light of this, we wished to present a suggestion on the ways Los Angeles could mitigate the Heat Island Effect. We would like to suggest the revitalization of the Los Angeles River, which would cool down the surrounding areas and give a safe, environmentally friendly place for its citizens. Another was lining the streets with small canals like Germany’s Freiburg Bächle (Gutters) and South Korea’s Jeonju/Gwanghwamun Mulgil (Water Path). Doing so would enlarge the reach of the water path, cooling down the entire city rather than the area of the stream.

If you would like to learn more, please check out Ji Hyun Park and Ji Sun Park’s full project:

Heat Island PowerPoint

The Urban Heat Island Effect (Full)