President Obama’s energy adviser has suggested all the world’s roofs should be painted white as part of efforts to slow global warming.

Professor Steven Chu, the US Energy Secretary, said the unusual proposal would mean homes in hot countries would save energy and money on air conditioning by deflecting the sun’s rays.

More pale surfaces could also slow global warming by reflecting heat into space rather than allowing it to be absorbed by dark surfaces where it is trapped by greenhouse gases and increases temperatures.

In a wide-ranging discussion at the three-day Nobel laureate Symposium in London, the Professor described climate change as a “crisis situation”, and called for a whole host of measures to be introduced, from promoting energy efficiency to renewable energy such as wind, wave and solar.

The Nobel Prize-winning physicist said the US was not considering any large scale “geo-engineering” projects where science is used to reverse global warming, but was in favour of “white roofs everywhere”.

He said lightening roofs and roads in urban environments would offset the global warming effects of all the cars in the world for 11 years.

“If you look at all the buildings and if you make the roofs white and if you make the pavement more of a concrete type of colour rather than a black type of colour and if you do that uniformally, that would be the equivalent of… reducing the carbon emissions due to all the cars in the world by 11 years – just taking them off the road for 11 years,” he said.

The three day Nobel laureate Symposium will end in a memorandum that is likely to influence any international agreement on climate change at the end of this year in Copenhagen.

Environmentalists insist the developed world must commit to cutting carbon emissions in order to set an example for poorer countries.

Secretary Chu said he was optimistic the US could lead the way through energy efficiency measures and boosting the use of renewables like solar, wind, nuclear and clean coal.

“The US will move, inevitably it will move first, as a more developed country we should be moving first, and I hope China will follow,” he said.

The symposium has gathered some 60 scientific experts and 20 Nobel Laureates to talk about climate change.

The high level meeting, hosted by the Royal Society and the Prince of Wales, is likely to influence any international agreement on climate change at the end of this year.