Painting Rooftops White Would Slow Global Warming

Study: If we painted every rooftop in 100 major cities white, it would offset the entire planet’s carbon dioxide emissions for one year. That’s nearly 44 metric gigatons.

Going green just turned white.

It makes sense. We all know white reflects heat (that’s why we wear white shirts and dresses on hot days), and we even knew that painting rooftops white lessens the need for air conditioning. But until now, we didn’t know that changing darkcolored surfaces to white would help fight against global warming.

The news broke yesterday at California’s Climate Change Research Conference. Hashem Akbari, attending the conference from the Lawrence Berkeley National Laboratory, announced that replacing dark shingles on an average-sized household rooftop with a lighter color would offset 10 metric tons of carbon dioxidecomparable to taking two mid-sized cars off the road for a year.

Speaking of roadways, they’re part of the problem too. Because of its cheap nature, most roads are paved with black asphalt instead of light grey concrete, which causes roads to absorb an inordinate amount of heat. Repaving roads with lighter-colored materials would have a similar impact to painting rooftops.

California already mandates that newly-built large buildings have light-colored rooftops, but the law was intended to decrease air conditioning costs. Akbari hopes to enlist the United Nations in an effort to convince major cities to make their roadways and rooftops more pale.

Read a full summary of the report here.

Photo Credit: Robert Whitlock on Flickr under Creative Commons license.

  1. JMD

    What global warming? Global temperature data show the warming stopped in 1998. Temps have actually declined in the last couple of years. How many more years of no warming must we have before people stop scheming about ways to address this phantom menace?

    We have more to fear from a colder world that from a warmer one. Cold shrinks the world’s temperate zones where most food is grown. It also forces us to use more energy to heat our homes and places of work.

  2. RM

    So what! There is no evidence of man-made global warming. The global temperature of seven of the last ten years have been below normal! Spend 10 minutes researching on the internet and you see so much evidence against global warming. August had no sunspot activity, the first time in decades – the winter will be a cold one.

  3. RM

    Hey JMD,
    in a few years they tell us that they were wrong it carbon actually causes global cooling so to save the planet, blah, blah, blah….

  4. caz

    OMG..will this lunacy ever end??? Not one environmentalist has ever been able to tell me what will happen after we decimate our economy to comply with all these ludicrous schemes. What will the temperature be? What storms will we avert? Honestly people…WE CAN CHANGE the climate about as much as we could make it rain on mars. We can’t and I would like just for once for people to stop playing God and believing that we have ANY CONTROL whatsoever on our climate. How incrediby arrogant!

  5. Metyu

    Er… Plenty of us have been saying for years that painting roofs white would help solve this “problem”.

    It’s just a shame that so many environmentalists aren’t listening. In the rush to introduce stupid taxes and economic systems, environmentalists won’t listen to anyone that doesn’t love Gore and think that Kyoto-2 or whatever will “save” the planet.

  6. Metyu

    Thanks for the link though.

    Is there perchance any research shoing how a doubling of the size of cities in the last 50 years has contributed to the planets warming?

    That would really upset Hansen et al…

  7. Chris

    “We all know white reflects heat (that’s why we wear white shirts and dresses on hot days)” Ah, but is it really so simple? In the Middle East, wearing all black is common. It was explained in a first-year physics text book that wearing loose, black clothing creates a convection current that actually helps cool the body better than wearing white does. See, that’s the danger with overly-simplistic thinking – other factors constantly get missed.

    There also might be some factor (minor, but cumulative) to having dark roof tops in Northern climates leading to slightly lower heating/energy needs.

    As for roads, you may want to consult an engineer, but I would think that painting an entire road would negatively impact a tire’s ability to properly grip the surface, in addition to possibly making daytime visibility more difficult (white roads on a sunny day would be pretty blinding). But then again, I suppose cars are “evil” so who cares anyway?

  8. Luke

    Calculations which involve the planets albedo are always tricky, as a major contributor to the planet’s reflectivity is cloud cover; which is a nightmare to simulate on its own and of course dependant on climate.
    I would suppose that if we were to consider this as a geoengineering technique it would be best to consider how rural landscape can be altered (crop selection?) as cities occupy only a small fraction of land area.
    The Californian track, saving air conditioning costs, is far more marketable to the average consumer. If it has additional benefits, even better. It’s part of the broader message that needs to be got out there, preserving your environment should be saving you money!


  9. ivy

    This is an easy thing to do. There is a product available called snow white that you paint on it’s so easy to do and great for your house.

  10. ivy

    Once during a renovation of a trailer we accidentally removed the fasteners holding the tin roof on, thinking that it was alright to leave overnight we went home. The home owners awoke in the middle of the night to a terrific noise. The wind peeled back the tin roof like a sardine can. The construction company was very clever. They solved the problem by painting on a great product that you roll on like paint.it is white and I think it is called snow white.A great insulator,and a great solution for anyone needing an inexpensive new roof. It gave the home owners a new roof and we left knowing the job was well done and now I can feel better knowing I did the enivorment a favor instead of just scaring the hell out of two very nice elderly people. The noise was so loud it nearly gave them a heart attack.

  11. Aaron

    I thought that it would make some sense to once again rub the dumb little doggies faces in their rhetorical poop. An excellent example follows:

    Quoting caz:

    OMG..will this lunacy ever end??? Not one environmentalist has ever been able to tell me what will happen after we decimate our economy to comply with all these ludicrous schemes. What will the temperature be? What storms will we avert? Honestly people…WE CAN CHANGE the climate about as much as we could make it rain on mars. We can’t and I would like just for once for people to stop playing God and believing that we have ANY CONTROL whatsoever on our climate. How incrediby arrogant!”

    Mmmm-kay… well, we don’t need to talk to an “environmentalist” for this one, really. How about we go to the Bush Administrations Environmental Protection Agency for this chestnut:

    Quoting the EPA:

    “Careful measurements have confirmed that greenhouse gas emissions are increasing and that human activities (principally, the burning of fossil fuels and changes in land use) are the primary cause. Human activities have caused the atmospheric concentrations of carbon dioxide and methane to be higher today than at any point during the last 650,000 years. Scientists agree it is very likely that most of the global average warming since the mid-20th century is due to human-induced increases in greenhouse gases, rather than to natural causes.”

    I’ll swat caz with the paper, too. The National Climactic Data Center (a branch of the U.S. Department of Commerce) mentions that:

    “There has been a general, but not global, tendency toward reduced diurnal temperature range (DTR: the difference between daily high or maximum and daily low or minimum temperatures) over about 70% of the global land mass since the middle of the 20th century. However, for the period 1979-2005 the DTR shows no trend since the trend in both maximum and minimum temperatures for the same period are virtually identical; both showing a strong warming signal.”

    Bad caz! Baaaaad!

  12. Marc

    what does this mean about all those black solar panels we are supposed to install on our rooftops? will heat absorption by solar panels be the next cause of global warming?

  13. Standard

    Please research HAARP (an invention by Nikola Tesla in the late 1800s) Your right, as far as compliance. I would never do something like that for a hoax. And that is exactly what global warming is. So are the new hurricanes in the GOM. Before the 1970s, history was taught that it had to be conspired to happen. Now we are taught that it just happens without reason. Fundemental ideas and intuition are taboo in the west and that is why no one here can detect outright lies right in front of them. Your intuition is the only key to the truth. That means check your conscience and ego at the door.

  14. Adam Williams

    @ Chris – Your all-black in the Middle East is a bit off the mark. For women, yes. White can be seen through and I think we all understand why that won’t fly for women in the Middle East. Men tend to wear white because it is cooler for all of the well-known and stated reasons.

    To all naysayers, in general, on this topic…

    The Earth was once thought flat, too. Could it be that you/we don’t know everything?

    Even if science hadn’t substantiated the existence of global warming, something which has even been accepted by Bush’s government, then at the least, I wonder this:

    Why take the chance?

    Don’t we often prepare for the worst and hope for the best? Just what if our actions are having a tragic impact on our environment — and consequently human existence? Isn’t it smarter to start living in reasonable ways rather than assume an all-is-well, nothing-can-happen-to-me posture?

  15. StanDonguard

    Umm… I live in a cold climate. Dark coloured roads help make them safe when they hold heat from the day and melt snow and ice during dark hours. Can we keep them, please?

  16. Tim

    @Adam Williams – “Why take the chance?”

    Many of the proposed changes that experts, governments, and lobbyists argue for are too extreme when we consider that the certainty of doom due to anthropogenic global warming is not certain at all or very clear.

    I find it odd that we, as humans, are fallible only until it comes to the much touted and vaulted climate models that we have created. Climate models cannot yet accurately predict (using the scientific definition of prediction) what the Earth’s climate will be like in the future.

    At this point we must take the chance and study our planet further until a deeper understanding is reached.

  17. Shawn K

    This might make an impact in places that use nothing but air conditioning, but anywhere that has to HEAT a building would use far more electricity to keep it warm than it does to keep it cool. For places like North Dakota, this is a BAD IDEA. We’ll take all the heat absorption we can get.

  18. Stan

    Chopping down trees in the north will increase the earth’s albedo by allowing the sun’s rays to be reflected by snow cover.
    Gentlemen, Start Your Chain Saws!

  19. David

    This is splendid idea. What will it do to my heating bill and gas consumption in the winter?
    David from Canada (at the end of an extraordinarily short and cool summer)

  20. Michael

    If 99% of astrophysicists told you that an asteroid was on a collision course with earth and was going to kill millions of people and change the climate, and 1% said it was going to miss the earth, would you take the chance the 1% was right? And if the one thing you could do that might have some chance to save the earth was to paint your roof white, would you say no?
    Global warming theory might be wrong. By the time we all are absolutely sure one way or another it will be too late to affect it. Are you willing to take that chance?

  21. Nick

    Oh my god. This is seriously reaching. You global warming freaks are clearly on your last lap. Paint roofs white? That is silly. It will do absolutely NOTHING to REDUCE carbon emissions. Last I checked a sedentary roof doesn’t PRODUCE a single molecule of co2. Yes, it will reflect sunlight. But what good is reflecting sunlight back into a haze of co2? How much co2 is produced when you make a gallon of paint? I’m sure its plenty. And it takes a lot of paint to cover and entire roof. This is clearly desperation. I love the idea of reducing carbon emissions, it can’t hurt. But this is such a bad idea, I’ll poop on it.

  22. Adam

    The summary illustrates a huge flaw in the analysis. A comparison is made to greenhouses where the glass is whitewashed in order to keep the greenhouse cool. Clearly by whitewashing our rooftops and roads (OK, just making them more grey) we can reduce global heating significantly. Except that the analogy is faulty. You don’t whitewash the floor of the greenhouse, you whitewash the GLASS. In our analogy of “Carbon Dioxide creates a greenhouse around the earth” we would have to paint the atmosphere and prevent the solar radiation from ever reaching the surface.

    If the technique is going to have a cooling effect on the atmosphere (as opposed to simply reducing the amount of energy used for AC) then you need to talk about the fact that the light reflected is primarily in the visible range, which passes through the atmosphere where as when it is absorbed, it is re-radiated out in the IR band, which is primarily absorbed by CO2 (I think that’s right, I forgot most of this a long time ago). This is NOT the same mechanism as employed by greenhouses (which is effectively shading).

  23. Alex Felsinger

    Maybe a good solution for areas with severe weather changes from season-to-season would be a double-sided plate/cover to put on top of the roof. Then you could flip it over from white to black when it starts getting cold.

  24. Amie

    This whole “human” induced global warming is ridiculous to begin with. But now to suggest painting rooftops? The earth is always changing and that means the climate too!! Things have always gone extinct and things have always adapted. This global warming is just another cycle of the earth. Yes, I’m sure we can contribute to it, but we are not the main cause. Painting rooftops is not going to SOLVE anything.

  25. Donal Buckley

    For the myth that that there’s no evidence of global warming or that 7 of the last 10 years are colder see:

    As for environmentalists loving Kyoto & Gore etc…I’ve be working in business for 28 years, don’t wear sandals or have a beard. I don’t think “business” is bad. I think Kyoto sucks, as do many so-called “tree-huggers” and I’ve never seen the Al Gore movie.
    Growing awareness of things I saw around me made me go out get educated in the facts ( I did a Master’s on the subject in my spare time out of interest).
    However I do understand that change to current living methods isn’t necessarily bad. Change drives innovation and new industries and will be hugely advantageous to those countries that embrace it.
    Much climate change denial comes from a) ignorance of the mechanisms and the facts and b) a co-dependency relationship with the advantages of modern western living. To deny any change means to be continue in the current vein is acceptable.

  26. matt

    Wow, people like Caz are so wrong. Gee it would be nice to think that mankind couldn’t possibly affect climate change. Unfortunately Caz, we have. And if you’d been doing your homework you would know that global climate change, grossly attributable to carbon emissions, is real.
    Wise up dickweed!

  27. Reply to Caz

    Dude, we CAN make it rain on Mars. That’s what terraforming is. I don’t think eco-engineering to change the climate is good, but painting roofs white ISN’T eco-engineering anyway. It’s just a white roof. If that’s playing God, then wtf does God even do?

    And in response to the article:
    This ONLY offsets warming, not carbon emissions or pollution. So it’s not a full solution, and the erratic weather like the recent increased frequency of hurricanes will continue.

  28. Alitari

    If we wanted to, with present day technology, we could make it rain on Mars … and while global climate change was started by warming, it doesn’t mean that warming is the be all and end all of it. Most models predict that we will see a wider range of temperatures, hotter, colder, wetter, drier … there’s this beautiful thing called homeostasis, where systems end up being balanced … throw a system as complicated as a global climate out of balance, and we’ll see a whole range of things.

    My question, though, is at what latitude would the logic of painting one’s roof white stop? While it’s nice and all to increase the albedo of the planet, in northern climates, where colder temperatures prevail, having a white roof will result in higher heating bills in the winter. And at what latitude should we paint our roof grey?

  29. Cokehead

    Wow..Someone thought it intelligent of them to post criticism of climate change, several times, as if to create census on the issue.

    Most scientists agree that climate change is happening; almost all of them agree that we’re the problem.

    I’d like to see some nonbiased sources about these claims of temperature dropping. I really would. What with the heatwaves in Europe, the heatwaves in the West a few years ago..Yeah, you’re going to need to prove that.

    As for ‘economic catastrophe’, I’d like a denier to explain to me this: After the massive socioeconomic and ecological collapse caused by climate change, what are you planning on doing?


  30. SaveOurSkyline

    I’m also going to wear a big white chef hat around to reflect even more UV. Seriously though, has the author of this piece thought about all the implications of the extra paint/roof production, the transportation carbon that gets used, etc.? Of course not. Plus, it’s effing WHITE. it’s going to get DIRTY, which means that it will no longer be white, it’ll be brown, unless you scrub it all the time. it’s good that people are thinking on their feet about possible solutions, but the solutions need critical thought applied.

  31. Me

    Well, I don’t know about places in warm climates, but darker roadways where icy roads can be an issue are a better plan. Warmer pavement means less icing.

  32. Kes

    This is misguided. Where will the reflected heat go? … back into the atmosphere. So, it won’t really slow down “global” warming cuz the heat will still be in the atmosphere.

  33. ronnie

    yea whatever……lets paint them all white so ones in cooler climates that benefit from winter solar gaines from a dark roof will spend alot more on heating cost, what about better insulation to reduce cooling demands on biuldings and homes, that would benefit us all.I live in a hot climate and insulation and ventilation is key.If we could just get rid of humans……….maybe blinding white roads would be the answer….

  34. miss amy

    haha. paint the roads white? that’s not at all what was said. make the roads out of lighter colored concrete. *smacks head in disbelief*

  35. CarolinaPhysics

    Test in Saudi Arabian desert proved that white vs. black tee shirts on Marines with thermostats on body showed absolutely no difference at all. White cotton does not reflect more HEAT than black cotton (more light, of course).

  36. PERRY

    O Aquecimento Global, é sim uma realidade, a cada dia q passa vai piorando. Temos como evidência disso alguns animais (bioindicadores) como por exemplo os anfíbios, que estão entrando em extinção, pois necessitam de lugares úmidos para sobreviver, e esses ambientes estão ficando cada vez mais escassos. A medida de pintar os telhados de branco é muito boa, no entanto, tem que ser mais efetiva, não apenas com propagandas na TV ou no rádio, mas com pessoas nas praças, Shopping Center’s, praias, passando nas casas alertando distribuindo folhetos e tudo o mais.Dessa forma talvez tenhamos resultados mais efetivos.Tudo o que passa só na TV, a população acostuma, e daí não dão bola pra isso, é como se fosse mais uma propaganda de liquidação de alguma loja de roupas ou ferramentas. Uma idéia que acho interessante, em se tratando de pintar os telhados das casas de branco, seria escolher ruas e sortear moradores que terão seus telhados pintados, e daí os escolhidos darão uma pequena colaboração para o gasto com a tinta. Temos que fazer essas idéias serem executadas de fato, temos que lutar contra o aquecimento global antes que seja tarde demais, porque nesse planeta, a natureza sempre vai conseguir se renovar, mas e a nossa espécie???

  37. Tyson Van

    Hey Dumb@$$e$. In the winter less heat will be absorbed, thereby requiring you to run your heater more, thereby offsetting any benefit of this completely stupid idea.

  38. seattle architect

    as an architect i am quite familiar with this concept of reducing heat-island effects from dark materials such as asphalt – though this phenomena as i understand it is a micro-climate effect. if we looked at the effect of painting all roofs white, i would be surprised if it would have a positive effect globally…that head must go somewhere, no? i don’t think its leaving the atmosphere…and that’s fundamentaly the problem (cause) of climate change.

  39. Uncle B

    The huge paradigm shift in American lifestyle, dictated by the great repuglican depression, and being delivered to the American people as we speak and post partem, in form of and astounding fall in the dollar, world wide, and an unbelievable inflation to follow,and the upcoming ‘Financial derivatives” holocaust, combined with the Asian factorhas changed the American situation forever.
    It will significantly reduce the amount of beef consumed in America. when in conjunction with rising oil prices, Obama’s Universal Health care taxes and the astounding Trillions of dollars being printed by government kick in and inflation hits the roof!
    Americans eat possum out of necessity in Detroit City today, and scratch in humanured, composted, garden plots by shanties, and live in unspeakable third world conditions in slums, where before, the mighty American Automotive manufacturing industries prevailed!
    America is “Morphing” into a less polluting society as we speak, and witnessing the Ohio Vally , now a non-polluting rust belt of human despair, I for one am not so sure we see improvement!
    Global Warming, true or false, is not an American responsibility! China does more damage in a day than we do, white roofs or not! India a close second! We are struggling, floundering, and folks on our continent are hurting! This is a global problem requiring Global regulation, and local efforts are frivolous fancy, relatively ineffective, in scale with “Global” regulations!
    Super insulations, the technologies updated, released by NASA and made public to community colleges can do more for the environment and fuel savings than any other single act, and we paid for this info and these new space age materials to be developed! Give it to us Washington!
    Depleted Uranium research must be made open to the public! Super battery potential exists here! Cold Fusion potential exists here! For “Defense Purposes” we are being held back! restricted to access to possibly the greatest field of science ever! goddammit! By Us!

  40. Moji

    Those cities don’t really cover as big a chunk of earth as you probably imagine. This sounds like wishy-washy BS that will never happen.

  41. Eli Elliott

    I think the Idea of using white paint is retarded, it should be a moss, lichen or algae roof with a waste water recycling solar powered self watering green roof & walls that would at least put off 02 and clean the air look nice and consume solar radiation. what cha think ?

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