Dr Steven Chu, Nobel-prize winning scientist and US Secretary of Energy, says we need to paint our roofs and footpaths white, and ensure our cars are white or light (cool) colours.
Highly reflective (ie white or silver) roofs allow sunlight to be reflected back into the atmosphere at normal wavelengths, rather than becoming absorbed into dark roof material and being converted to heat. This means the wavelengths bypass the greenhouse gases that trap heat radiated from the Earth, and thereby reduce global warming.
This idea was the subject of scientist Hashem Akbari’s study at Lawrence Berkley (California). Akbari launched a campaign to encourage a switch to white roofs earlier this year. The solution is particularly useful in warmer climates where cooling is more of an issue than heating, and some of the hottest cities in the world, such as in the Mediterranean, already favour white or cool colours for their buildings.
Painting it white may not tackle the root causes of global warming, however. In itself, it would undoubtedly help with the symptoms (the warming). But it may also help with reducing a building’s carbon footprint by reducing the need for air conditioning in summer, a saving in energy cost. However, in cooler climates it is less effective, though calculations show that overall, except in the coldest climates, it is worthwhile to paint roofs white. One drawback for cooler climes is that, for white roofs to be most effective, attic insulation needs to be removed, obviously something not desirable in a cold northern (or southern) winter.
Making roofs highly reflective is a good idea, overall, as they are well above the eyeline for most people, but turning footpaths into highly reflective surfaces may cause problems. Intense glare impairs visibility and causes fatigue. There could be side-effects from the stress of glare that have as yet not been taken into account. Thought needs to be given to the impact of bathing the population in the light being bounced back into space.