With over half of the entire human population living in cities, it is important to
understand how cities can be affected by climate change, and to devise strategies to
employ adaptation strategies to deal with possible impacts. NASA plays an
increasingly important role in research into climate change and its potential
impacts on the quality of life on earth. This includes several thrusts of research
into the impact on urban life on climate change. One such effort at NASA involves
utilizing green (a.k.a. vegetated) roofs.
NASA's research reveals that roofs covered with vegetation provide a cleaner environment, energy savings, and increased insulation. Additionally, utilization of green roofs can dramatically reduce the surface temperature of urban environments, something critically important for elderly and other sensitive populations.
NASA utilises remote sensors on earth-observing satellites to provide thermal imaging
to measure the temperature of the earth’s surfaces, these thermal images are used to
create computer models to forecast climate change causes and effects. The resulting
models incorporate analysis of thermal images showing urban surfaces and surrounding
geographical areas and their temperatures and are used to produce maps of surfaces
and land cover in urban and surrounding areas to show differences in summer surface
These maps help examine how much a city consisted of “impervious” surfaces such as street asphalt, concrete and dark colored roofs. An example; the 2002 thermal model of New York City (NYC) showed that dark colored roofs account for about 13% of the NYC land surface area, some 30 square miles citywide see figure 1.
Summer surface temperatures in urban areas were shown to be on average, 13-16 degrees Fahrenheit (7.2-8.9 degrees Celsius) warmer than surrounding rural areas, which have more forested and vegetative cover. This phenomenon is known as the Urban Heat Island (UHI) Effect.
This results from absorption of the sun’s energy by concrete and asphalt street surfaces as well as by dark colored building roofs by day and by tall buildings which keep heat from escaping to the sky at night.