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”.