Invent roofs with adjustable reflection coefficient
Expanding on the suggestion by Hashem Akbari's to combat climate change by painting all roofs and paved surfaces in the USA white, our idea is to develop roof materials that can change their reflection coefficient by changing their colour to cover a range from black to white. Regions like Vancouver, with warm summers and cold winters, should have white roofs in the summer and black roofs in the winter, to minimize air conditioning and heating energy needs throughout the year. Roofs with adjustable reflection coefficient could be "dimmed" from inside a house as simply as a light. Smart house technology could even automate this process.
Currently exploring an approach to addressing cool roofs, green roofs & walls.