Dark material gets warmer in sunlight than light-coloured or white material. Heat energy enters our atmosphere after light strikes the surface of the Earth, is partially converted into heat, which then radiates into the air. White stuff reflects the sun’s energy straight back into space without converting as much of it into heat.
Because of this, melting ice sheets isn’t only a result of climate change, it causes more. Shiny white ice is replaced by darker ground or ocean, meaning more heat entering the climate system. Cities too, with their dark roads, create ‘heat islands’ that contribute to warming the atmosphere.
But what if we made the Earth more reflective? Less heat entering the system, counteracting the heat trapping effect of greenhouse gases, reduced climate change.
It’s actually not that hard.
Just painting the dark roof of a 100m2 house white offsets 10 tons of carbon emissions – over half of average annual emissions per person. So there’s something each person can do at a personal level that makes a real difference.
According to a study, making the roofs and paved areas of the 100 largest cities in the world whiter would have the same effect as the whole world not emitting greenhouse gases for a year – or, put another way, would offset 11 years of emissions growth. Secretary of Energy Steven Chu talks about the concept with Jon Stewart here:
The great thing about this as part of tackling climate change is its simplicity. Every individual can choose to play their part for no extra cost when repainting, repainting, or installing a roof ( more than that, white roofs save money on cooling in summer but don’t increase heating costs in winter). The government can provide leadership very easily just by lightening the colour of asphalt used in state highways. One step further would be providing small subsidies to lighter coloured house paints etc.
Of course, this is just a part of the complete programme we need, NOW, to confront climate change but I think it’s awesome that this shows we can make a difference with simple, clever actions.