LOS ANGELES, Sept. 10 (Xinhua) -- White roofs, which have a massive cooling effect, can slow global warming, newly-released data showed.
If the 100 biggest cities in the world installed white roofs and changed their pavement to more reflective materials like concrete instead of asphalt-based material, the global cooling effect would be massive, according to data released at the on-going annual Climate Change Research Conference in Sacramenta, capital of California on Wednesday.
Globally, roofs account for 25 percent of the surface of most cities, and pavement accounts for about 35 percent.
If all were switched to reflective material in 100 major urban areas, it would offset 44 metric gigatons of greenhouse gases, which have been trapping heat in the atmosphere and altering the climate on a potentially dangerous scale, the data showed.
That is more than all the countries on Earth emit in a single year. And, with global climate negotiators focused on limiting a rapid increase in emissions, installing cool roofs and pavements would offset more than 10 years of emissions growth, even without slashing industrial pollution, according to the data.
A 1,000-square-foot roof, the average size on an American home, offsets 10 metric tons of planet-heating carbon dioxide emissions in the atmosphere if dark-colored shingles or coatings are replaced with white material, according to Hashem Akbari, a physicist with the Lawrence Berkeley National Laboratory.