Painting roofs, roads and pavements white to make them reflect more of sunlight could be one way to fight global warming, suggests Prof.Steven Chu, a Nobel laureate and current US Energy Secretary.
A co-winner of Nobel Prize for Physics back in 1997, the 61-year-old Prof.Chu is a vocal advocate for more research into alternative energy and nuclear power, arguing that a shift away from fossil fuels is essential to combat global warming.
Speaking at the opening of the St James's Palace Nobel Laureate Symposium, for which The Times is media partner, Prof.Chu claimed that by lightening all paved surfaces and roofs to the colour of cement, it would be possible to reduce carbon emissions drastically - it would be like all the world's cars off the roads for 11 years.
Pale surfaces reflect up to 80 per cent of the sunlight that falls on them, compared to about 20 per cent for dark ones, which is why roofs and walls in hot countries are often whitewashed. An increase in the number of pale surfaces would help contain climate change both by reflecting more solar radiation into space and by reducing the amount of energy needed to keep buildings cool by air-conditioning.
Hence building regulations should insist that all flat roofs are painted white, while visible tilted roofs could be painted with "cool coloured" paints that look normal, but which absorb much less heat than conventional dark surfaces. Roads could be lightened to a concrete colour so they do not dazzle drivers in bright sunlight.
I think with flat-type roofs you can't even see, yes, I think you should regulate quite frankly," Professor Chu said. "I would be in favour of that."
Asked whether governments should be promoting white paint as a solution to climate change, he said: "Yes, absolutely... White roofs everywhere, yes."
Professor Chu said his thinking on the issue had been strongly influenced by Art Rosenfeld, a member of the California Energy Commission who drove through tough new building commissions in the state. Since 2005, California has required all flat roofs on commercial buildings to be painted white, and the measure is being expanded this year to mandate cool-colours on all residential and tilted roofs as well.
Dr Rosenfeld is also a physicist at the Lawrence Berkeley National Laboratory in California, of which Professor Chu was director until he was appointed Energy Secretary. Last year, Dr Rosenfeld and two colleagues from the laboratory, Hashem Akbari and Surabi Menon, calculated that changing surface colours in 100 of the world's largest cities could save the equivalent of 44 billion tonnes of carbon dioxide - about as much as global carbon emissions are expected to rise by over the next decade.
He said that while flat roofs should be white, tilted, visible surfaces could be improved using "cool-coloured" paints designed to look normal while reflecting much more infrared light. These could also be used to cut the petrol consumption of cars, by reducing their need for air-conditioning.
Professor Chu said the demands of climate change required a revolution in both energy efficiency and generation. "The industrial revolution was a revolution in the use of energy," he said. "It offloaded from human and animal power into using fossil fuels. We have to go to a different new revolution that can severely decrease the amount of carbon emissions in the generation of energy."
The US needs to scale up its investment in clean energy research massively, he said, citing the example of other high-technology industries that routinely spend 10 to 20 per cent of their income on research. The US spends $1 trillion on generating electricity, but "nothing like" the $100bn to $200bn on research and development that would meet that standard, he said.