In the year 2000, the average global temperature increased about 33°F since the 70's. Each summer, temperatures are expected to continue rising at this rate. Whether you realize it or not, building owners all over the city have been paying more and more every summer. Hotter temperatures mean hotter rooftops, and rooftops – especially black ones – are notorious for absorbing heat and transmitting it to the rooms below. As rooms heat up, residents are forced to turn up the AC or simply deal with it.
Most cities have a greater abundance of dark surfaces and roofs, making urban areas retain larger amounts of heat than surrounding rural areas. This phenomenon is called Urban Heat Island (UHI).
Because dark roofs have low albedo and retain more heat, city residences tend to use more energy to cool their homes. On a hot summer day, a dark roof could reach temperatures up to 185°F*.
For You. The higher temperature means increased energy consumptions for cooling and higher electricity bill.
For Everyone. Increase in energy usage releases more greenhouse gases by burning more fossil fuels.
For the Future. With the current rate of greenhouse gas emissions, studies show that by 2100, a hot summer day would reach temperatures of roughly 137°F**!
A collection of Urban Heat Islands can considerably contribute to Global Warming or the more correct term, Climate Change. In 1896, Svante Arrhenius predicted that doubling carbon emissions could raise global temperatures 5-6° C or 41-42° F***. Effects could, and has begun to, cause animal extinction, climate fluctuations, and glacier melting, which will endanger entire ecosystems and consequential effect human lifestyles. Not to mention sea level rising, which is a real and imminent threat, especially for the Southern parts of NYC.
"By 2100 scientists project that sea levels along New York's coastlines and estuaries will likely be 18 to 50 inches higher, though they could be as much as 75 inches higher."
* Wong, Hogan, Rosenberg, & Denny . Reducing Urban Heating Islands: Cool Roofs. US EPA.
** Meehl, Washington, Collins, Arblaster, Hu, Buja, Strand, & Teng . How Much More Global Warming and Sea Level Rise? Science, Volume 307.
*** Houghton, J. . Global Warming. Institute of Physics Publishing.