Weather Making Cities – What Can Be Done To Change It?

ambience: sounds from a metropolitan area

As our urban areas grow, so do the number of buildings, roads and sidewalks. The sunlight hitting these surfaces can turn a city into an island of heat. I’m Jim Metzner, and this is the Pulse of the Planet. There are ways to cool a city down. Dale Quattrochi , a senior scientist with NASA’s Marshall Space Flight Center, says that we can start by planting trees.

“Although we see where cities in the eastern United States have a lot of trees, they are not strategically placed. There are vast deserts in cities and many cases where there are no trees at all. Planting the right kinds of trees. Trees that are not contributors to the whole process of ozone. Trees can give off biological emissions that, in fact, enhance the overall ozone problem. It’s best to go in and plant the right kind of trees, and plant them strategically around the city so that it helps to shade the surface.”

Dale Quattrochi recommends oaks as especially effective shade trees. And he says that there are steps that cities can take to lessen the so-called urban heat island effect.

“Contrary to what most people may think, the hottest surfaces in cities are not necessarily pavements, but the rooftops. And rooftops are warm because they’re predominately dark colored. And of course black absorbs heat, and it retains this heat and releases it later on in the evening. And so our basic question is, why is it that roofs as well as other surfaces have to be black? Why can’t there be other lighter colors for example? Or even highly reflective materials? We’ve been working with roofing manufacturers whereby they actually have materials that can be put on large roofs that reflect on the order of about 60 to 80 percent of the incoming sunlight. And so therefore they reflect this back out into the open sky and it does not contribute to the whole urban heat island effect.”

Pulse of the Planet is presented by the National Science Foundation. I’m Jim Metzner.

music

Weather Making Cities - What Can Be Done To Change It?

Rooftop surfaces and strategically planted trees can ease the heat of urban environments.
Air Date:07/17/2009
Scientist:
Transcript:

ambience: sounds from a metropolitan area

As our urban areas grow, so do the number of buildings, roads and sidewalks. The sunlight hitting these surfaces can turn a city into an island of heat. I'm Jim Metzner, and this is the Pulse of the Planet. There are ways to cool a city down. Dale Quattrochi , a senior scientist with NASA's Marshall Space Flight Center, says that we can start by planting trees.

"Although we see where cities in the eastern United States have a lot of trees, they are not strategically placed. There are vast deserts in cities and many cases where there are no trees at all. Planting the right kinds of trees. Trees that are not contributors to the whole process of ozone. Trees can give off biological emissions that, in fact, enhance the overall ozone problem. It's best to go in and plant the right kind of trees, and plant them strategically around the city so that it helps to shade the surface."

Dale Quattrochi recommends oaks as especially effective shade trees. And he says that there are steps that cities can take to lessen the so-called urban heat island effect.

"Contrary to what most people may think, the hottest surfaces in cities are not necessarily pavements, but the rooftops. And rooftops are warm because they're predominately dark colored. And of course black absorbs heat, and it retains this heat and releases it later on in the evening. And so our basic question is, why is it that roofs as well as other surfaces have to be black? Why can't there be other lighter colors for example? Or even highly reflective materials? We've been working with roofing manufacturers whereby they actually have materials that can be put on large roofs that reflect on the order of about 60 to 80 percent of the incoming sunlight. And so therefore they reflect this back out into the open sky and it does not contribute to the whole urban heat island effect."

Pulse of the Planet is presented by the National Science Foundation. I'm Jim Metzner.

music