health and it affects energy consumption. Those two things alone are

enough to drive worldwide interest. (Zhang) When we

build an urban area, we're replacing the vegetated surface and also

the soil surface with this imperious surface like the

paving material and the building material. By doing this, we're basically

warming the urban areas, and this will generate a temperature difference.

And that's what we can the urban heat island. We find out

that the urban heat island affected by several factors.

The first factor will be the surrounding ecological context.

And then will be the size of the city. When talking about size, we can

we mean both the area of the city and also the population size

of the city. And then will be the shape of the city

and also the development patterns of the city.

(Imhoff) We used a variety of satellite data, both land surface data

from MODIS and also impervious surface data from the

Landsat satellite. Inpervious surface data essentially tells us

how much building material is on the land surface in order to study the urban

heat island. The urban heat island is much larger if you

convert a forested area into an urban. And this is because the urban

heat island is a relative measure. So, urban areas in forests

are much warmer than the surrounding landscape than they are in deserts

for example, because the surrounding landscape is already warm.

I think the general public should be interested in urban heat islands because of the

fact that it's where most of the people live and in the next

50 years, we're going to see 80% of the global population living in

cities. And the urban heat island matters for

everything from health, like asthma and heart conditions,

to how much heating and air conditioning you need to use to

cool or heat your living space.

(beeping)