January 12, 2018
The New York Times reported on the devastating wildfires that Californians have been experiencing, explaining that the incidence of wildfires is clearly exacerbated by climate change. The article further links the wildfires in Southern California to a phenomenon known as the urban heat island effect – where metropolitan areas become significantly warmer than their neighboring rural areas due to human activity.
In the article researchers point out that although there are a number of climate factors at play in these wildfires, the urban heat island effect could in fact be contributing significantly to these disasters. It is likely that urban heat islands are reducing cloud cover, a critical aid to maintaining ground moisture. Increased ground moisture is helpful in reducing dry brush that fuels these massive fires.
The effects of the urban heat island should be a priority for sustainability managers at the local level. In 2015 the California EPA released an Urban Heat Island Index to help local and state agencies better understand the impacts of urban heat island across California. The accompanying report finds several interesting phenomena: winds can shift urban heat from coastal to inland regions and “urban heat island archipelagos” can form in regions such as Riverside-San Bernardino due to large areas of urban development.
Urban Heat Island Index maps from the California EPA show that the Los Angeles region has significant urban heat islands in comparison to other cities in the state. Recognizing the negative effects of urban heat islands on the climate and health, the City of Los Angeles passed a mandatory cool roof ordinance in 2014 that will help reduce heat build from their buildings. The cool roof ordinance along with coating roads with “cool” paint and urban tree planting will help the city reach its target of reducing the urban/rural heat differential by 3 degrees by 2035.
Although other cities in California have yet to set specific targets for urban heat reduction many have begun taking action to reduce urban heat islands. In the US EPA’s Heat Island Community Action Database you can find local and state efforts to reduce urban heat to learn more about what steps you can take to implement projects to mitigate or study the effects of urban heat islands in your community.