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Earth Power Technology

Painting The World's Roofs White Could Slow Climate Change 712

Posted by timothy
from the why-do-you-think-they-paint-ice-white? dept.
Hugh Pickens writes "Dr. Steven Chu, the Nobel prize-winning physicist appointed by President Obama as Energy Secretary, wants to paint the world white. Chu said at the opening of the St James's Palace Nobel Laureate Symposium that by lightening paved surfaces and roofs to the color of cement, it would be possible to cut carbon emissions by as much as taking all the world's cars off the roads for 11 years. Pale surfaces reflect up to 80 percent of the sunlight that falls on them, compared with about 20 percent for dark ones, which is why roofs and walls in hot countries are often whitewashed." (Continues, below.)
"An increase in pale surfaces would help to contain climate change both by reflecting more solar radiation into space and by reducing the amount of energy needed to keep buildings cool by air-conditioning. Since 2005 California has required all flat roofs on commercial buildings to be white and Georgia and Florida give incentives to owners who install white or light-colored roofs. Put another way, boosting how much urban rooftops reflect would be a one-time carbon-offset equivalent to preventing 44 billion tons of CO2 from entering the atmosphere. 'For the first time, we're equating the value of reflective roof surfaces and CO2 reduction,' says Dr. Hashem Akbari. 'This does not make the problem of global warming go away. But we can buy ourselves some time.'"
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Painting The World's Roofs White Could Slow Climate Change

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  • Pavement (Score:4, Interesting)

    by jasonhamilton (673330) <jason&tyrannical,org> on Wednesday May 27, 2009 @05:02PM (#28114955) Homepage

    Makes me wonder why roofs and not pavement. There's a lot of roads and parking lots around the world. Seems like there's more surface area of those than roofs.

    • Re:Pavement (Score:5, Informative)

      by Chabo (880571) on Wednesday May 27, 2009 @05:06PM (#28115041) Homepage Journal

      From TFS:

      that by lightening paved surfaces and roofs to the color of cement

      Personally, I wouldn't want to drive on a surface that bright; I'd be squinting even with my sunglasses on!

      Also, as a current resident of California, I can see the value in having a light-colored car or house, but as a former resident of New Hampshire, I can tell you that having a black car and black roof on a cold but sunny winter's day is very helpful! Snow slides off my car roof with ease, and it means I didn't have to turn the heat up quite so much!

      • Re:Pavement (Score:5, Insightful)

        by Jah-Wren Ryel (80510) on Wednesday May 27, 2009 @05:08PM (#28115097)

        Personally, I wouldn't want to drive on a surface that bright; I'd be squinting even with my sunglasses on!

        If you've driven on an interstate in the mid-west, chances are you've driven on cement. It really isn't any worse than asphalt.

      • Re:Pavement (Score:5, Insightful)

        by Avin22 (1438931) on Wednesday May 27, 2009 @05:16PM (#28115241)
        Although this would reduce the amount of energy used for cooling, heating costs would go up. For most people, it takes far more energy to heat a house than cool it. It takes 1200 KWh to cool a house in a temperate climate for a year, but it takes 12000 KWh to heat one . It is more useful to look for ways to heat a house more efficiently than cool it.
        • Re:Pavement (Score:5, Insightful)

          by MarcoAtWork (28889) on Wednesday May 27, 2009 @05:23PM (#28115411)

          uhh, in the winter your roof is covered by snow anyways, so the color your roof is not going to make any difference. And for states/countries where it doesn't snow in the winter, you probably also don't need 12000KWh to heat them up.

          • There's snow on my roof perhaps 2 weeks tops during the winter. But I have to run my heat for over 6 months of the year. I topped 5000kwh on a 2500 sq ft house at a cost of $450 this december. Nice try, but...
            • Re: (Score:3, Insightful)

              by SatanicPuppy (611928) *

              It depends on where you live. Completely.

              First off, your home insulation should be good enough that you'd only see a modest benefit from the solar heating. Second, living that far north (above say, pennsylvania (39 degrees north/south for you furriners)) and the amount of daylight you get is pretty low in the winter anyway.

              I live in the South, and I run the AC between 6 and 8 months of the year, and, thanks to a big tornado earlier this year, I heated my house for most of our short winter using free firewoo

        • Re:Pavement (Score:5, Insightful)

          by syphax (189065) on Wednesday May 27, 2009 @05:27PM (#28115475) Journal

          In the winter, a dark, hot roof doesn't heat a house very effectively (heat rising and all that- plus there's less incident solar energy).

          In the summer, there's a lots of solar energy hitting your roof; and a hot roof leads to a hot attic, which retards flow of heat/hot air in the house (heat rising and all that).

          So, a light-colored roof has a much more profound impact on cooling than on heating.

          A metal roof will help both heating and cooling- and snow slides off them- but they are not cheap!

        • Re:Pavement (Score:5, Interesting)

          by drinkypoo (153816) <martin.espinoza@gmail.com> on Wednesday May 27, 2009 @06:16PM (#28116235) Homepage Journal

          The other replies have told you why you are wrong. I will tell you how to harness the principle to your benefit, but it has nothing to do with your roof. I saw it in Mother Earth News (how apparently ironic that the acronym is MEN) but the idea is old; you paint the exterior wall black, cover it with a sheet of glass or plastic, and put a vent at the top and bottom. In the summer you would prefer to cover it with white shutters to reflect unwanted solar energy. In winter, you open the shutters and the vents. Convection provides circulation.

          In theory, you could do the same thing on your roof, but you'd need some sort of forced air system to bring the air down where you can use it; all you need in your home is a ceiling fan.

        • Re:Pavement (Score:5, Informative)

          by Stevecrox (962208) on Wednesday May 27, 2009 @06:41PM (#28116507) Journal
          A house built to with heat conservation in mind should almost heat itself. I've moved into a new flat building in the UK, between all the insulation and double glazing its actually hard for me to get the flat cooler than 21 degrees.

          During the winter when it reached -8 degrees outside, my flat without any heating was at 16 degrees. My neighbours have the same issue, we only have the one small flat below us so the heat isn't coming from downstairs.

          I can think of several other new buildings which suffer from this problem. If your going to argue about the color of a building mandating improved heat conservation should remove most of the heating costs.
      • Re:Pavement (Score:4, Informative)

        by Dare nMc (468959) on Wednesday May 27, 2009 @06:43PM (#28116535)

        In physics, a black body is a perfect absorber of light, but by a rule derived by Einstein it is also, when heated, the best emitter. [wikipedia.org]
        so if your house/car/etc is heated, then yes it emits more heat from the body if black. Thus it is a worse insulator and (as you observed) heats the snow on the outside of your car faster. So yes if your goal is to heat the outside of your car in winter, black is best. If keeping the stuff on the inside warmer than the outside, is your goal, it may not be best in black (definitely not assuming a lack of radiated light, like at night.)

    • Re:Pavement (Score:5, Insightful)

      by Dutchy Wutchy (547108) on Wednesday May 27, 2009 @05:12PM (#28115159)
      If the roads are painted white with the standard white road paint, the coefficient of friction will be reduced (much more so when wet).

      Also, where is all this paint coming from? What are the environmental and economic impacts of making all of this paint?

    • Re:Pavement (Score:5, Informative)

      by cdub1900 (1167623) on Wednesday May 27, 2009 @05:29PM (#28115515)
      Believe it or not, there is a lot of research going into creating lighter colored surfaces for roads. One of the advantages is that it takes less light (and thus energy) to light up the surface at night. This also decreases the amount of "light pollution" you would have around town. There are other advantages to improving water quality and decreasing noise.

      http://www.eoearth.org/article/Cool_paving [eoearth.org]

      However, one of the current hangups is how to keep them light? Unless we can also change the rubber in the tires to be lighter color as well, the road surfaces just end up black again in high traffic areas like California.
      • Re: (Score:3, Funny)

        by Chabo (880571)

        Unless we can also change the rubber in the tires to be lighter color as well

        A comeback for white-wall tires? Awesome!

    • Re:Pavement (Score:4, Insightful)

      by CarpetShark (865376) on Wednesday May 27, 2009 @05:50PM (#28115867)

      Makes me wonder why roofs and not pavement. There's a lot of roads and parking lots around the world. Seems like there's more surface area of those than roofs.

      What you have to understand is that there's climate change, and the movement to save the environment. Then, there's "global warming" and the movement to sell you yet more products that can "save the environment!!" (despite the fact that selling unnecessary products and not living simply enough is the main cause of damage)

    • Re: (Score:3, Interesting)

      by Mike_K (138858)

      While others have pointed out that the article DOES talk about pavement, there is an additional reason to paint roofs before roads: roofs overheat our houses and we use more a/c to cool them off. Roads to not need cooling (though cars on them do, but that is a secondary effect).

      m

  • by snsh (968808) on Wednesday May 27, 2009 @05:05PM (#28115009)
    Let's also paint all the Grizzly bears white. That will address the problem of disappearing polar bears.
  • Moon (Score:4, Funny)

    by SnarfQuest (469614) on Wednesday May 27, 2009 @05:05PM (#28115019)

    Everyone should hang their bare white bottoms out the window, in order to reverse the global warming trend.

  • and make all (Score:5, Interesting)

    by markringen (1501853) on Wednesday May 27, 2009 @05:06PM (#28115037)
    and make all the birds blind. we had a man in the neighborhood who had a white roof and it was filled with dead birds. birds fly towards white objects for some reason as if it's the sky, and splatter to death.
  • Time out (Score:3, Interesting)

    by XanC (644172) on Wednesday May 27, 2009 @05:06PM (#28115047)

    Wasn't there a study a year or two ago, which was loudly trumpeted by NPR, CNN, MSNBC, etc, that concluded that manmade global warming (or "climate change") was already a sure thing, and it was way past too late for us to do anything about it now.

    So, uh... What happened to that? Was that fake, or is this guy ignorant? Or do climate-change types believe stuff whenever it's convenient for them?

    • Re:Time out (Score:5, Insightful)

      by Tenek (738297) on Wednesday May 27, 2009 @05:11PM (#28115149)
      Maybe there's some legitimate debate over how reversible it is, independently of whether or not it's happening.
    • Re:Time out (Score:5, Insightful)

      by MrMista_B (891430) on Wednesday May 27, 2009 @05:12PM (#28115153)

      No, that was accurate - the climate is changing all the time, and humans have caused various changes to accelerate in ways that are detrimental to the survival of our species (growth of deserts, loss of farmland, etc.)

      What this is proposing, is a way to mitigate some of the detrimental changes.

      That aside, why the snark? I understand that people of course have personal investment in their enviroment (it's where we live, after all), but for someone proposing a simple change like this that could have multiple beneficial results for our species, I'm not sure why you feel so threatened.

    • Re: (Score:3, Insightful)

      by SnarfQuest (469614)

      Or do climate-change types believe stuff whenever it's convenient for them?

      yes

    • Re:Time out (Score:4, Insightful)

      by stpere (450329) <stpere.gmail@com> on Wednesday May 27, 2009 @05:20PM (#28115329)

      Well, even if we can't reverse the process, there are other good reasons to lower our energy consumption.

      Energy isn't free; by polluting less, you often spend less in the long run... It's not only good for the planet, it's good for the economy in general.

      Both shouldn't be seen as incompatible things.

    • Re: (Score:3, Insightful)

      by Mashiki (184564)

      Don't you know? The wind blows one way, than the other. We're doomed, then not doomed. Followed by we're so guilty we're already screwed that we should just wipe out humanity for the next apex species.

      Yeah, seriously this stuff gets old pretty quick. Half the reason why you can't take stalk in most of it.

    • Re: (Score:3, Informative)

      by pcolaman (1208838)
      The fact that it was reported by NPR, CNN, and MSNBC tells me all I need to know about the likeliness of it being a legit claim. My only question is which analyst on which of those networks pulled the claim out of their ass and allow the other networks to co opt that info.
  • Unfortunately... (Score:3, Insightful)

    by scsirob (246572) on Wednesday May 27, 2009 @05:06PM (#28115049)
    Unfortunately, producing the massive amounts of white paint needed to paint all these surfaces and maintain them produces about as much CO2 as was saved by starting this excellent project.
    • Re: (Score:3, Informative)

      by hankwang (413283) *

      Unfortunately, producing the massive amounts of white paint needed to paint all these surfaces and maintain them produces about as much CO2 as was saved by starting this excellent project.

      You need about 100 g of paint to cover a square meter. Suppose that the paint costs 1 kg worth of fuel to manufacture. The amount of sunlight it reflects over 10 years in a sunny climate is on the order of 50 gigajoules, or about 1000 kg of fuel to burn. Even if only 10% of the heat has to be cooled away by airconditioning

  • White asphalt? (Score:4, Interesting)

    by idontgno (624372) on Wednesday May 27, 2009 @05:08PM (#28115093) Journal

    Now, you smile, but he's done a calculation, and if you take all the buildings and make their roofs white and if you make the pavement more of a concrete type of colour rather than a black type of colour, and you do this uniformly . . . it's the equivalent of reducing the carbon emissions due to all the cars on the road for 11 years.

    Now all we need is white tar...

    • by 13bPower (869223)

      You can get that in Afghanistan.

    • Re:White asphalt? (Score:5, Insightful)

      by JSBiff (87824) on Wednesday May 27, 2009 @05:14PM (#28115205) Journal

      There might be some safety issues with making road surfaces reflect more light. . .things that come to mind:

      * Increased road glare on sunny days - good sun glasses could largely deal with this, but if you don't happen to have a pair of sunglasses, you might be having a pretty hard time seeing on very bright days.

      * Night driving: harder to see the painted lines and reflectors embedded in the concrete (I'm not sure if this would really be much of a problem or not, but maybe could be)

      * Winter driving - In the winter, I'm sure that black pavement absorbing sunlight has some beneficial effect in the form of melting ice off the road sooner than light-colored pavement would. Lighter colored road surfaces might lead to ice lasting longer, or requiring more salt to be put on the roads by road crews.

  • Other Pollution (Score:3, Interesting)

    by ironicsky (569792) on Wednesday May 27, 2009 @05:08PM (#28115095) Journal
    I wonder if he calculated the amount of green house gas and other pollution would be created by manufacturing all this new paint. If they were you make roofing tiles and shingles white, what would the pollution cost from people throwing out their old roofs to bring in new white ones? Same with roads. My favorite roof solution, and something I plan on working on this summer or next summer is to turn my garage roof in to a natural garden by placing a protective tar paper over the shingles, a couple of inches of dirt and then grass or moss seeds. I'll let nature reclaim my man-made structure. Inch for inch, it would be just like grass growing on the ground, except not.
  • White roofs (Score:3, Informative)

    by Geoffrey.landis (926948) on Wednesday May 27, 2009 @05:09PM (#28115117) Homepage
    Not really new: Knight science journalism tracker link [mit.edu], Christian Science Monitor Blog: [csmonitor.com]

    and, the original source: Powerpoint presentation from LBL: "Global Cooling: Increasing World-wideUrban Albedos to Offset CO2," Hashem Akbari PDF file [mit.edu]

  • Double benefit (Score:3, Informative)

    by EvilToiletPaper (1226390) on Wednesday May 27, 2009 @05:10PM (#28115133)
    Whitewash also absorbs CO2 from the atmosphere and turns into Calcium carbonate to get that milky white look, so in addition to reflecting sunlight, we also remove some CO2 from the air. On the downside, whitewashed walls look butt ugly.

    Anyone know what the environment/economic cost of making all that whitewash is?
  • by sampson7 (536545) on Wednesday May 27, 2009 @05:10PM (#28115137)
    There are very free lunches in the world of energy production and consumption. Lightening the color of pavement and roofing materials about as close as we get. From a DOE study [osti.gov]:

    As an example, computer simulations for Los Angeles, CA show that resurfacing about two-third of the pavements and rooftops with reflective surfaces and planting three trees per house can cool down LA by an average of 2-3K. This reduction in air temperature will reduce urban smog exposure in the LA basin by roughly the same amount as removing the basin entire onroad vehicle exhaust. Heat island mitigation is an effective air pollution control strategy, more than paying for itself in cooling energy cost savings. We estimate that the cooling energy savings in U.S. from cool surfaces and shade trees, when fully implemented, is about $5 billion per year (about $100 per air-conditioned house).

    Amazing, isn't it? Two to three degrees in temperature reduction in a major city just by resurfacing, repainting, and planting trees. Yeah, sure, it's not sexy. But the cost savings ... staggering. Add in the health benefits of reducing smog, plus the reduction of human misery from over-heated citys, and you wonder why we haven't done this years ago.

    I know this is going to sound like a self-serving political statement from a hardcore Democrat -- but well done, President Obama. You picked a scientist to run an agency. You gave him a mission to better humanity through reducing carbon emissions and energy consumption. You gave him a platform where he would be heard. Well done indeed.

    • well done, President Obama. You picked a scientist to run an agency. You gave him a mission to better humanity through reducing carbon emissions and energy consumption. You gave him a platform where he would be heard.

      Heard, but will he be heeded?
      Cynic says no.

    • by radtea (464814) on Wednesday May 27, 2009 @05:41PM (#28115725)

      I know this is going to sound like a self-serving political statement from a hardcore Democrat -- but well done, President Obama.

      My cynicism knows no bounds, which gives me to think what the Democratic response to this might have been if a Bush Administration official had proposed it. I'm betting something to the tune of, "Oh those damned Republicans they want to use band-aid technological fixes so they can go on driving their SUVs over baby polar bears for another ten years!"

      I think this is a good idea, and if Chu can make it happen (again, colour me cynical) it'll be a good thing, particularly because of the reduced energy demand aspect, which will help with the whole peak oil deal.

      But I can't help thinking about how mindless partisans (not necessarily you) would have reacted if the Offence rather than the Defence had suggested this (both parties are ultimately on the same team, of course, representing the plutocrats united against the people.)

  • by Culture20 (968837) on Wednesday May 27, 2009 @05:14PM (#28115197)
    That's nice for the hot countries. What about cold countries? Maybe we like having black roofs and roads to melt the snow faster if there's a little opening?
    • by pz (113803) on Wednesday May 27, 2009 @05:30PM (#28115539) Journal

      That's nice for the hot countries. What about cold countries? Maybe we like having black roofs and roads to melt the snow faster if there's a little opening?

      Yes. Or nearly so. I just happened to be doing some research on roof treatments. There are basically two types -- for flat roofs. Angled roofs are a different story since they're angled for snow and rain shedding. The two types of flat-roof coatings are white paint and aluminum paint.

      Here's the link: http://eetd.lbl.gov/coolroof/coating.htm [lbl.gov]

      White paint coatings use titanium dioxide as a pigment (very, very white) and reflect 70-80 percent of incident light. That means they keep the roof cool in the summer. They are, however, reasonably transparent to IR from below, so unfortunately do nothing to hold heat in during the winter.

      Aluminum paint coatings use little flakes of alumnimum and reflect about 50-60 percent of incident light. That means they also keep the roof cool in the summer. They are, however, much less transparent to IR from below, so help keep in heat during the winter by reflecting it back down.

      Then again, nothing stops you from painting your flat roof white or aluminum and unrolling black sheeting during the winter to help absorb heat from the sun.

  • by tiedyejeremy (559815) on Wednesday May 27, 2009 @05:18PM (#28115285) Homepage Journal
    White paint CAUSES GLOBAL WARMING by reflecting light into the atmosphere! http://www.rushlimbaugh.com/home/daily/site_032609/content/01125110.guest.html [rushlimbaugh.com]
    • by geekoid (135745) <dadinportland AT yahoo DOT com> on Wednesday May 27, 2009 @05:36PM (#28115633) Homepage Journal

      "I don't want to get too technical on this black paint versus white paint and reflection of heat and so forth because it misses the point."
      He always says something like that and what it really means is "I don't want to get too technical on this [Inser topic] becasue there are no technical aspects to my argument that are true.

      Fight it on the rights issue, but don't fight it on a science issue when you do not understand the science.

    • by SatanicPuppy (611928) * <Satanicpuppy&gmail,com> on Wednesday May 27, 2009 @05:47PM (#28115815) Journal

      Wow, I think this is the first time I've ever heard him say something nice about something black.

      • by el_gato_borracho (1218808) on Wednesday May 27, 2009 @08:41PM (#28117685)
        Rush Limbaugh does sound like a doofus when he tries to talk about science, but he is no racist. He consistently agrees with Dr King's ideal of judging people by the content of their character, not the color of their skin. Rush agrees with and supports people who agree with his political viewpoint regardless of skin color, and opposes those who disagree in like kind. A man who had a problem with black people would not let Dr Walter Williams guest host his show so often, would not interview Justice Clarence Thomas on his program, etc. It saddens me that politics has become so polarized that it is considered normal for people who never listen to Rush Limbaugh to "know" that he is a racist, plus get modded funny based on that smear.
    • Re: (Score:3, Interesting)

      by mrsquid0 (1335303)

      Someone needs to tell that caller about the difference between optical light and infrared light. I wonder if he has ever tried to boil coffee with a flashlight.

  • by Hankenstein (107201) on Wednesday May 27, 2009 @05:20PM (#28115339) Homepage

    Or we could put solar panels on roofs and convert the sunlight, that would ordinarily be
    converted to heat, into electricity which I am sure we could find a use for.

  • Ridiculous (Score:5, Interesting)

    by jdb2 (800046) * on Wednesday May 27, 2009 @05:26PM (#28115461) Journal
    Paint roofs white? With the efficiency increases in photo-electric technology, why not put solar panels on every roof? Not only would we reduce the amount of heat being re-radiated back into the atmosphere but, if done on a global scale, we'd eliminate one of the primary reasons for climate change in the first place : the burning of fossil fuels. And before you respond with "but it will cost too much and generate more CO2 than it eliminates" let me give you one word : Bootstrapping [wikipedia.org]. That's right -- Use the power from the existing global infrastructure for solar energy capture to build more global infrastructure for solar energy capture; That way, you would generate a minimal amount of greenhouse gases in the manufacture of new solar panels while at the same time creating a self-sustaining positive feedback loop wherein the more energy we can capture, the more energy capture infrastructure we can build, resulting in our ability to capture more energy.

    I didn't RTFA but the summary sounds retarded.

    jdb2
  • by puppetman (131489) on Wednesday May 27, 2009 @05:27PM (#28115467) Homepage

    and sea levels, but not for the pH balance of the oceans, which are acidifying as they absorb additional carbon [wikipedia.org] from the atmosphere.

    I remember reading about green roofs (growing plants etc on the roof of buildings) and the effect it had on temperatures when done in urban environments [wikipedia.org]:

    Reduce heating (by adding mass and thermal resistance value) and cooling (by evaporative cooling) loads on a building â" especially if it is glassed in so as to act as a terrarium and passive solar heat reservoir â" a concentration of green roofs in an urban area can even reduce the city's average temperatures during the summer.

    The Fairmont Hotel, here in Vancouver BC does this, growing herbs for the hotel kitchens. [uwaterloo.ca]

  • by flyingfsck (986395) on Wednesday May 27, 2009 @05:31PM (#28115555)
    Uhmmm, even painting the all the cities in the world mirror silver won't achieve anything. The world is much, much larger than the cities. Three quarters of the globe is covered in water. A miniscule part of the 25% that is land mass is covered in cities.
  • What about heat? (Score:3, Interesting)

    by IGnatius T Foobar (4328) on Wednesday May 27, 2009 @05:35PM (#28115617) Homepage Journal
    This brilliant "idea" fails to take into consideration the fact that in the winter, sunlight falling on a roof does add to the heat inside the house. If the roof were a light color, that heat would have to be replaced by burning some sort of fuel. So unless you're in a location that never needs heat, the idea doesn't work.

    Personally I don't believe there is such a thing as anthropomorphic climate change, but if I did, I would still keep my roof a dark color.
  • Or... (Score:3, Insightful)

    by Endo13 (1000782) on Wednesday May 27, 2009 @05:38PM (#28115653)

    it could be possible that the global climate change is just part of a natural cycle, and is actually a good thing. But hey, let's just ignore that possibility and try every idea no matter how stupid that we can possibly think of to "fix" it.

    Seriously, if science has taught us *anything* it's that tampering with things we don't understand almost always makes them worse. Even when - actually, maybe that should be especially when - we're trying to "correct" a "mistake we've made".

  • by phallstrom (69697) on Wednesday May 27, 2009 @05:53PM (#28115907)

    Wouldn't it be better to simply plant grass instead? Ignoring the problem of having to reinforce roofs that is...

  • by Skapare (16644) on Wednesday May 27, 2009 @06:33PM (#28116409) Homepage

    ... by painting all the solar cells on my roof white. But I'm gonna have to do this all over again because these solar cells aren't making any electricity.

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