I have been pushing white or reflecting roofs as the lowest cost climate strategy (see “Geoengineering, adaptation and mitigation, Part 2: White roofs are the trillion-dollar solution“). Indeed, it is almost certainly the single cheapest of the 12 to 14 wedges needed to stabilize near 2°C total warming — the equivalent to taking the world’s approximately 600 million cars off the road for 18 years, while quickly paying for itself in direct energy savings!
[100 m2 (~1000 ft2) of a white roof, replacing a dark roof, offsets the emission of 10 tonnes of CO2.]
So I was delighted when a reader sent me this amazing Agence France-Presse story from Tuesday:
US Energy Secretary Steven Chu said Tuesday the Obama administration wanted to paint roofs an energy-reflecting white, as he took part in a climate change symposium in London.
The Nobel laureate in physics called for a “new revolution” in energy generation to cut greenhouse gas emissions.
But he warned there was no silver bullet for tackling climate change, and said a range of measures should be introduced, including painting flat roofs white.
Making roads and roofs a paler colour could have the equivalent effect of taking every car in the world off the road for 11 years, Chu said.
It was a geo-engineering scheme that was “completely benign” and would keep buildings cooler and reduce energy use from air conditioning, as well as reflecting sunlight back away from the Earth.
I would add that by reducing the urban heat island effect (along with shade tree planting), white roofs are also the lowest cost “adaptation” strategy, directly cooling a city. So it is perhaps the one true triple play in climate — mitigation, geo-engineering, and adaptation — that is also both low-cost and scalable.
For people who found white hard on the eye, scientists had also developed “cool colours” which looked to the human eye like normal ones, but reflect heat like pale colours even if they are darker shades.
And painting cars in cool or light colours could deliver considerable savings on energy use for air conditioning units, he said.
Speaking at the start of a symposium on climate change hosted by the Prince of Wales and attended by more than 20 Nobel laureates, Chu said fresh thinking was required to cut the amount of carbon created by power generation.
He said: “The industrial revolution was a revolution in the use of energy. 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.”
Since I have been writing about white roofs and urban heat island mitigation (UHIM) for a long time, the readers who sent me this clip wrote:
Chu and Obama are listening to you on this!
While I suppose that’s possible — I’m told people at DOE and the White House do read this blog — in fact there is a far more plausible explanation. The person who introduced me to white roofs and UHIM more than a decade and a half ago, the person with whom I co-authored numerous articles on this subject — including this 1997 Technology Review overview article, “Paint the Town White-and Green” — is California Energy Commissioner Art Rosenfeld.
Rosenfeld co-developed this whole new geo-engineering analysis with Lawrence Berkeley National Laboratory’s Hashem Akbari. You can read their non-technical summary, “White Roofs Cool the World, Directly Offset CO2 and Delay Global Warming.” And Rosenfeld is a friend of Chu’s, which is no surprise since they are both (brilliant) physicists and former LBNL scientists who focus on energy energy issues.
But provenance aside, if the U.S. Energy Secretary is publicly advancing white/reflective roofs at an international meeting, that means you can expect serious national and even international action on this important climate strategy.