Whitewashing vs. global warming

One of the simplest ways of slowing down global warming would be to paint the world’s roofs white or pastel shades and maybe the world’s asphalt highways as well.  White reflects heat; black absorbs heat.  A study released this week by the U.S. Department of Energy says that if all the roofs in the temperate and tropic zones were painted white, it would mitigate global warming as much as taking all the world’s automobiles off the road for 20 years.

If you want to stimulate the economy, why not put people to work painting roofs and roads.  It would be a more straightforward way of stimulating the economy than giving tax credits to businesses and home buyers; it would be a more straightforward way of mitigating global warming than cap-and-trade or subsidies for the windmill industry.

Now maybe there are technical objections to this that I don’t see, but I think that main problem with it is that our dysfunctional political and economic system is incapable of implementing simple and obvious solutions to problems.  Until the white paint industry forms a powerful lobbying group, there is no way of even getting this discussed.

Our politicians and political commentators take it for granted that it is impossible for government to actually achieve anything, as if this were a law of nature, like the impossibility of faster-than-light travel, which only whining liberals would ever complain about.  But I am old enough to remember that things weren’t always this way, and they don’t have to be this way.

I do applaud Energy Secretary Stephen Chu for his decision to have the Department of Energy’s own roofs painted white.  I think this is the best way for government to promote energy conservation and renewable energy – to create a market for it along with incentives to improve performance and bring down price.

Another reason that action on global climate change is that the benefit will go to the next generation, not us today.  The melting glaciers, unseasonably hot summers and extreme weather events of today are due to emissions of greenhouse gasses during the Reagan years and before (and would be a lot worse than they are if not for the energy conservation initiatives of the Carter administration).  What we do today will determine how much worse things are 30 years from now.

Click on Cool Roofs Can Mitigate Global Warming for Lawrence Berkeley National Laboratory’s summary of its DOE study.

Click on Whitening Cities Roofs Is Environmental Equivalent of Taking 300 Million Cars Off the Road for Popular Science’s report on the DOE study.

Whitening the world’s roofs would offset the emissions of the world’s cars for 20 years, according to a new study from Lawrence Berkeley National Laboratory.

Overall, installing lighter-colored roofs and pavement can cancel the heat effect of two years of global carbon dioxide emissions, Berkeley Lab says. It’s the first roof-cooling study to use a global model to examine the issue.

The study used a global land surface model from NASA’s Goddard Space Flight Center, which contained regional information on surface variables like topography, evaporation, radiation and temperature, as well as on cloud cover, Berkeley Lab says.

Lightening-up roofs and pavement can offset 57 billion metric tons of carbon dioxide, about double the amount the world emitted in 2006, the study found. It was published in the journal Environmental Research Letters.

Researchers used a conservative estimate of increased albedo, or solar reflection, suggesting that purely white roofs would be even better. They increased the albedo of all roofs by 0.25 and pavement by 0.15. That means a black roof, which has an albedo of zero, would only need to be replaced by a roof of a cooler color — which might be more feasible to implement than a snowy white roof, Berkeley Lab says.

The researchers extrapolated a roof’s CO2 offset over its average lifespan. If all roofs were converted to white or cool colors, they would offset … 1.2 gigatons per year. That equates to offsetting the emissions of roughly 300 million cars, all the cars in the world, for 20 years.

I first came across this information on Duncan Black’s Eschaton web log.

[Note 7/28/10]  The original title was Greening by whitewashing but painting buildings white, while it may mitigate global climate change, doesn’t have anything to do with green (i.e., renewable) energy.

One Response to “Whitewashing vs. global warming”

  1. Anita Says:

    Great post. I didn’t know this. We will have to redo our roof in the next few years – this gives us a chance to do something helpful. If it’s good enough for Stephen Chu, it’s good enough for me.

    A good related blog post from Ezra Klein yesterday: http://voices.washingtonpost.com/ezra-klein/2010/07/why_a_climate_bill_failed.html#comments


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