It’s common knowledge that city dwellers experience higher temperatures than their neighboring rural counterparts. Climate change exacerbates the situation. For residents in the Denver Metro area, temperatures are rising faster than most cities.
Climate Central [.pdf], an organization that monitors climate change, discovered in a new study that of the 60 largest cities in the U.S., 57 of them had significantly higher temperatures than adjacent rural areas. In some cases those discrepancies had reached a difference in daytime highs by 27 degrees Fahrenheit.
Denver is only surpassed by Albuquerque and Las Vegas as the most significant heat island in the country, with an average difference of 4.9 degrees higher than surrounding areas. Las Vegas had a difference of 7.3 degrees while Albuquerque residents experience an average of 5.9 degrees warmer temperatures than nearby rural communities.
So what is the cause and what can be done to reverse the trend?
As more Americans move into urban centers, the heat indexes there are expected to continue to rise. More people mean more roads and buildings made of concrete and asphalt, which collect more heat as opposed to the forests and prairies in nearby rural areas. Vegetation naturally holds in moisture, causing a reduction in heat.
In Denver, some architects are experimenting with roofs covered in vegetation. Whether they are a park like setting or used to grow vegetables, these green roofs have the capacity to cool the city off.
Americans have been slower to adapt to the green roof trend, although the number has nearly quadrupled since 2004. Denver’s downtown regional Environmental Protection Agency building has a green roof used to grow vegetables. A study led by the EPA revealed that an adjacent building without the green roof fluctuated at more extreme temperatures while the EPA regional building’s vegetation did indeed keep the heat in check.
Other Denver buildings with green roofs include the Museum of Contemporary Art and Denver Botanic Gardens, the first publicly accessible green roof in the city. The top cities in the U.S. for green roofing are Washington D.C., Chicago and New York.
Roofs only account for part of the cause of Denver's unusual high temperatures. The city's streets and parking lots also contribute to the heat.
One initiative that may also help involves a move to add a million additional trees in Denver by the year 2025. In 2013, American Forests, a nonprofit organization that promotes healthy woodlands, placed Denver in the top 10 best cities for urban forests.
It's not just vegetation that can mitigate against rising heat in Denver. Reflective roofs, including solar panels deflect heat. A 2011 study by the University of California at San Diego found that solar panels reduce heat to buildings by 38 percent. To its credit, Denver made the top 10 [.pdf] for cities leading the nation in solar energy. For a city with 300 days of sunshine a year, the benefits are economic as well as environmental.
