Most Indians know, to their cost, that having a flat on the top floor means hot, stifling interiors. So what's the solution - a simple physics principle that a white or light coloured roof reflects more radiation than a dark one. In fact a white shiny plasticized cover is even better and this is what is being attempted from California to Dubai to New Delhi. White roofs reduce air conditioning costs by 20% and the consequent lower energy consumption has a direct bearing on global warming.
The numbers are almost unbelievable. Apparently turning all of the world’s roofs “light” over the next 20 years (easier said than done) could save the equivalent of 24 billion metric tons in carbon dioxide emissions. That's the whole world's total emission in a year.
The only downside is that in cold climates, correspondingly heating bills would rise slightly. However, this is an irrelevant issue for tropical countries like India.
Of course there have been white tiled roofs in hot climates for a long time. The idea is to make this catch on all over the world.
Some more information is available here along with some links.