Increasing Piñata Albedo


Remember when Tim Blair’s commenters combined to take on a six year old boy? And lost. Now Blair and his commenters are taking on a Nobel Physics Prize winner. On physics.

US Energy Secretary Steven Chu, one of the world’s greatest minds, believes painting roofs, roads and pavements white will help contain global warming. Reader Steve H. reviews the Chu plan:

According to a 2004 study by the U.S. Geophysical Union, all constructed so-called “impervious surfaces” (buildings, roads, parking lots, roofs, etc.) in the USA total a combined 112,610 km^2. Which is a bit less than the total area of Ohio, a bit more than Virginia.

That means we’ve got about 1.14% for Dr. Chu to paint.

That should make a big difference.

Vast coverage of the planet by human construction is a common assumption among greenoids, who evidently imagine that their own surrounds are a universal global standard.

Hmm, let’s do a quick check

the RF for a doubling of CO2 is likely 3.7±0.4 W/m2 – the same order of magnitude as an increase of solar forcing by 2%.

So changing the albedo of 1% of the Earth’s surface from 0 to 1 would negate 50% of the forcing from doubling CO2. Of course, the real change in albedo is somewhat less, and we can only do this on land, but it seems clear that changing the albedo of even a relatively small area will make a difference.

If you check the paper that Chu was referring to, you’ll discover that far from assuming “vast coverage of the planet by human construction”,

We estimate that urban areas are at least 1% of the Earth’s land area or about 1.5×10^12 m^2 (see Table 5). The roof area is 3.8×10^11 m^2. The paved surface area is
5.3×10^11 m2. We calculate a global RF of -4.4×10^-2 W/m^2 by cool roofs and cool
pavements.We then estimate the global emitted CO2 offset potentials for cool roofs
and cool pavements to be in the range of 24 Gt of CO2 and 20Gt of CO2, respectively,
giving a total global emitted CO2 offset potential range of 44 Gt of CO2. This 44 Gt CO2 offset is over 1 year of the 2025 projected world-wide emission of 37 Gt of CO2
per year.


  1. #1 aw
    June 2, 2009

    Well, one percent of the United States, which is itself less than two percent of the world’s surface… what kind of paint is this? and how is it manufactured?

  2. #2 WotWot
    June 2, 2009

    My house was re-roofed a few years back, and I deliberately got white roofing. (I live in the tropics.)

    Has one down side, you have to clean it every couple years or so to prevent the build up of dark mold, but that is a small price to pay for a cooler house.

  3. #3 Scott M
    June 2, 2009

    And for the record, Sec. Chu did not call for all roofs to be painted white (we’d wind up looking like a photograph negative of Ireland), he called for all FLAT roofs to be painted white. That’s already in the building code in several states. Didn’t take long for the anti-enviros to distort that, did it?

  4. #4 Eric
    June 2, 2009

    There is probably a net reduction in the absorption of radiation, but less than what is calculated. The heating season in temperate zones is about 1/2 of a year. Reflection of solar radiation from roofs would increase the need for heating and CO2 emissions during the heating season. Over time, the integrated increase in emissions could overcome the benefits of white roofs in the summertime.

    The paved areas would be hard to keep clean. In the winter time, the warming of outside air by pavement, in urban areas during the winter may be desirable to reduce the cost of heating as well.

    I would like to see a more in depth serious analysis of this proposal to get a better quantitative idea of the potential improvement.

  5. #5 Barry
    June 2, 2009

    Eric, that’s true, but from what Tim has shown us, it looks like the plan is based on quantitative analysis. It wasn’t like somebody took a big toke on the doobie and said ‘like, wow, man! What if we like, painte *all the roofs white*!….’.

  6. #6 Eli Rabett
    June 2, 2009

    Actually Eric, it is a winner in the heating season also if the roof paint is designed to have a lower emissivity (eg, like the white (ok light grayish) reflective membrane coating on my roof). In that case the amount of heat radiated into the atmosphere will be significantly less, lowering the heating costs.

    OTOH, you probably should ask if the membrane coating is reflective in the IR….

  7. #7 Dano
    June 2, 2009

    5-10% of the energy expenditure in cities is to offset the increase in the Urban Heat Island effect. Reducing this effect would make us more efficient.

    Why do delusionists and porcine AM radio hayturz hate capitalism and markets?



  8. #8 Michael
    June 2, 2009

    Tim, couple of typos – “cange”, and it should be “far from assuming”.

    And holy heck!, I’d never read the Pinata skit before.

    It’s as ugly as a hatful of armpits over at Blairs Blog of Stupid.

  9. #9 John Mashey
    June 2, 2009

    0)This stuff comes from the same LBNL (Lawrence Berkeley National Lab)folks like Art Rosenfeld, whose autobiography there is well worth reading, and you can find good presentations on cool roofs and other topics there.

    See cool roofs, June 3, 2009 PPR for example. LOOK AT THAT, if nothing else.

    They show colored alternatives that are not bad, since a lot of existing sloped home roofs aren’t likely to go all the way to white.

    LBNL folks helped give us more efficient fridges, high-frequency ballasts for CFLs, low-emissivity windows, etc. LBNL is probably the premier energy efficiency lab in the world. They do *not* just make up dumb numbers.

    1) Like I said over at Climate Progress.

    “This is the sort of long-hanging fruit that:

    a) Doesn’t need much, if any new technology.

    b) Doesn’t need big government funding.

    c) Can be done by:
    – Tweaking building codes sensibly, like we’ve already done here in CA
    – Using light paint where geographically sensible, when updating buildings

    d) Simply needs numerous people to understand there is value in doing this.

    e) Even saves money

    2) Rational people don’t insist that everyone rush out and paint houses tomorrow. Rational people don’t insist on doing this in areas that need heat, but no air conditioning. But, in lots of areas (US SouthWest, and big chunks of urban Oz), consider the asymmetry of heating and cooling in dense urban environments, especially where peak electricity usage is summer afternoons:

    If buildings need to be heated, and they are leaking heat, they may help each other out by raising the ambient air temperature. At least, they don’t hurt.

    If they need to be cooled, they raise the ambient air temperature, and have to work harder. I can feel that in the summer, just walking around downtown Palo Alto, *not* a dense urban place, but still, all those air conditioners are blasting away.

    From there, just 5 miles up the hill to our house there is a noticeable temperature gradient, partly from the hill, but much from having less UHI effect.

    This is what Stanford and Palo Alto have been doing lately. This actually saves money, in many cases (at Stanford) with *2-year paybacks*.

    Use GoogleEarth to fly around SiliconValley. See if you find any industrial buildings with light-colored roofs (if not solar panels). Why do they do that? ($$)

    Better roofs help here, but even more in Los Angeles (and most Oz cities, I’d guess).

    3) It is utterly mystifying that people can be *reflexively* against this, unless they make their living directly from coal, or POL2-/PSYCH-3 contrarianism from anti-science reasons.

    Thinking about albedo in the built environment is one of the lowest-hanging fruit around.

  10. #10 grayGaffer
    June 2, 2009

    My experience: tree shade keeps ground level cooler, but I guess it does not help the albedo from solar pov.

    White building decoration has a venerable history in the more southern centers of ancient human population. Look at the Greek Islands, for example.

  11. #11 Eli Rabett
    June 2, 2009

    Trees turn CO2 to wood and O2, they also transpire, which cools the area.

  12. #12 GaryB, FCD
    June 2, 2009

    Eric said “Reflection of solar radiation from roofs would increase the need for heating and CO2 emissions during the heating season. Over time, the integrated increase in emissions could overcome the benefits of white roofs in the summertime.”

    In the Great White North, we have enough insulation in our attics that the snow on the roof doesn’t melt until April/May.

    I’m sure that if you tropicalists just threw a little more insulation in your houses, having a white roof would not result in a significant increase in heating costs.

  13. #13 eddie
    June 3, 2009

    I second the first commenter. It’d be a terrible irony if they used oil-derived paint. The trees idea is better. I’d like to see flat roofs covered in plants. What they lack in albedo they make up for in carbon capture.
    Consider a living turf roof for insulation also.

  14. #14 Marion Delgado
    June 3, 2009

    plants will eat through most roofs.

  15. #15 Jeremy C
    June 3, 2009

    What about less black tarmac by having less roads?

    (PS. I hate traffic so will twist any discussion around to getting cars off roads)

  16. One possibility involves the colour of rocks used in the macadam matrix: even using black tar to hold the matrix together, the tar is quickly rubbed off the exposed rocks. How much lighter (and thus more reflective) would roads be if we used light grey or white rocks in pavement matrix? (Keep in mind, I am an historian, so if I am way off base here, just patiently explain please).

  17. #17 Interrobang
    June 3, 2009

    Along with what Gary B said, my roof is already white all winter long, because it has snow on it. Funnily enough, my attic is also full of high-grade insulation, but then again, so are the walls and everywhere else one would think to put insulation. Also funnily enough, replacing the windows with insulating double-glaze and adding the extra insulation in the attic and walls has dropped the heating bill, and keeps the house cooler now that the genuinely hot weather is here. Unlike most people, I don’t have air conditioning; what I do have is a house that was carefully constructed with consideration for the climate, so one can open the windows (on the sides of the house that catch the prevailing winds) and get great air circulation for free.

  18. #18 John Mashey
    June 3, 2009


    White (or other appropriate materials), or green roofs, better insulation, low-E windows, ultra-insulating blinds (like Hunter-Douglas Architellas), overhanging eaves, proper siting, trees….

    It’s not either/or, that’s a false dichotomy. Good green building design takes general principles and then applies them to the specific geography and site in rational ways.

    Here are two recent buildings that illustrate what can be done if you are serious:

    our Portola Valley Town Center rotating pictures, and
    a description of methods used, and building green advice.

    A place I visit often is: Carnegie Dept of Global Ecology. That one does have an interesting roof water system, but one would probably not try to do that as a retrofit.

    Some people have the idea that green buildings are ugly and unpleasant. These are beautiful, pleasant buildings and people *love* them.

    Also, there are clear differences between:
    – new buildings (and roads/parking lots)
    – serious retrofits
    – easy upgrades

    Painting roofs lighter is a relatively easy upgrade for some cases, but would need serious retrofit for others, i.e., you wouldn’t do it until ready to redo a roof.

    People have found green (vegetation) roofs to be very good in some places (like Chicago on top of skyscrapers). But consider a house with sloped roofs in Los Angeles, located in a desert where zero rain falls for ~7 months. One has to build an irrigation system and whether that’s a good use of water in a desert remains to be seen. Maybe someone does these for sloped roofs, but I’ll admit I haven’t seen any.

    Depending on where you are:
    a) Roofs may gather solar energy for electricity
    b) Roofs may gather solar energy to heat hot water (a real win, and one of the best)
    c) Or they at least reflect heat in places where that’s a good idea, and on parts of the roof where you it doesn’t make sense to do a) or b).

    Trees are good [and both CA towns I’ve lived in have tree logos :-)],but they also get in the road of a) and b) above. At least, better PV panels are coming that can handle mixed shade.

    Global warming is virtually certain, and global “peak energy” (at least for a while) is very likely, and doing buildings right helps both, and *it saves money*, especially over the life of a normal building.

  19. #19 Dave Andrews
    June 3, 2009


    Isn’t all this painting things white about reducing the UHI effect?

    But, I’m sure we have been told pretty consistently over the years that UHI has no measurable effect on global temperatures. If we are now to accept that it does have an effect does it not mean that the temp record is, as has often been claimed, considerably flawed?

  20. #20 MarkG
    June 3, 2009

    >But, I’m sure we have been told pretty consistently over the years that UHI has no measurable effect on global temperatures.

    I don’t think you’ve been told this. A consistent pattern amongst the so-called “denialists” is that although you are often not exactly sure what you disagree with you are very sure you disagree with it most strongly. Of course UHI contribute to global warming. Both directly in the form of local heating and indirectly, in the form of power usage in UHI effected areas to offset the local heating effects.

    The claim you are probably referring to is the standard denialist assertion that the warming signature shown in global temperatures is not real and only evident (either partially or entirely) because the temperature measurements all take place in UHI effected areas. All completely untrue of course, but that’s a whole other argument.

  21. #21 Dano
    June 3, 2009

    Dave, your fundamental ignorance on UHI is not only profound, but is what the Noise Machine counts on to spread its FUD to the credulous. BTW, the credulous number is decreasing, now about 15% of the population. As this demographic is the lonely white man undereducated in the sciences, one wonders whether an individual wants to associate themselves with this crew. Nonetheless,

    Some of my current work (and a tiny bit of my past work) is on the UHI. Today my work is in ameliorating it. There is a plethora of studies that show your assertion is yet another example of ignorance is a poor place to start an assertion. Don’t trot that out in educated company.



  22. #22 Marion Delgado
    June 4, 2009

    Dano I am surprised even you alarmists are still pushing these discredited Goreisms.

    Remember, the theory that lighter colors reflect more is just like the theory that heat rises – just that, only a theory. If you’re unwilling to teach the controversy, then you have to expect self-respecting skeptics to dismiss you and turn to Tim Ball, who at least gets the science right on melting ice.

  23. #23 Gaz
    June 4, 2009

    Marion, not only do lighter colours reflect more heat, they’re also not as slimming. So it’s no surprise to hear Al Gore’s name cropping up in the context of a solution that involves making something look fat.

    Anyway, who says white reflects heat.

    The Wilkins Ice Shelf is white and look what’s happening to it.

    I’ll never get to drive my Hummer across that damn ice bridge now.

  24. #24 Dano
    June 4, 2009

    All true, gents, but remember white is the ruling color for roofs and thus it is its destiny to rule. (this, of course, is why true patriots oppose white roofs and will go to war over the denial of white roofs)



  25. #25 dhogaza
    June 4, 2009

    But, I’m sure we have been told pretty consistently over the years that UHI has no measurable effect on global temperatures. If we are now to accept that it does have an effect does it not mean that the temp record is, as has often been claimed, considerably flawed?

    No, you’ve been told for years that UHI is accounted for in the adjustments made to the raw data used to create the global temperature record.

    The problem is that for years you haven’t listened to what is being said.

  26. #26 Marion Delgado
    June 4, 2009

    dhogaza, just this once i will “think of the children lurkers!”

    In addition to pointing out that urban heat islands were factored in and weighted appropriately (as a net result of a process the denialists didn’t follow), we also pointed out that you did NOT have to do a great deal of adjusting for them, because hot air rises. Hence a thermometer not far from a UHI will still be almost completely unaffected by it.

  27. #27 pough
    June 4, 2009

    And shouldn’t a change in albedo have a one-time effect on temperature anomaly? It’s not like a parking lot will have an increasing UHI effect over the years (or a white roof the opposite).

  28. #28 John Mashey
    June 4, 2009


    All this is *not* just for UHI.

    An IR photon from:

    a) A roof in Manhattan
    b) A roof in a suburb
    c) A roof on a farm in Kansas
    d) A road or parking lot *anywhere*.

    all count for global warming effects.

    While equal-energy photons have ~equivalent global effects, of course, having a lot of them in one place induces more cost/energy use for air-conditioning.

    See Figure 1.3 in Chapter 1, just the fraction of total pavement that is the national Highway System.

    This gives the statistics of roads and streets, per state, which of course, doesn’t count parking lots.

    Of course, in some places, a natural use of parking lots is to get covered with PV cells, like at Google (see GoogleEarth, parking lots at West end of main campus) or Applied Materials: see photos.

  29. #29 IM
    June 4, 2009

    “All true, gents, but remember white is the ruling color for roofs and thus it is its destiny to rule. (this, of course, is why true patriots oppose white roofs and will go to war over the denial of white roofs)”

    Not true. Saruman the white was defeated by Gandalf the Grey!

    [Yes, natural science is not my strong suit, but so what? Science doesn’t really matters in this debate anyway]

  30. #30 Trollhattan
    June 5, 2009

    Couple of notes: NASA and EPA did quite a bit of urban heat island research in the late ’90s, including U2 flyover measurements of my (usually sunny) city.

    Oddly, these efforts seemed to disappear in the new decade, as if something had somehow changed…. It’s good to have Dr. Chu and others like him in positions of influence today, as widespread “passive” efforts have lasting impact at minimal, if any cost (roofs and pavement, after all, have to be replaced intermittantly).

    Turns out you can reflect IR without resorting to a white material, which may be a boon to those who want the energy savings without calling attention to themselves as being hippie commie-sympathizer white-roof types.

    Folks mocking this concept (for completely apolitical reasons, of course) remind me of those who claimed that switching from incandescent to flourescent/LED lighting would consume MORE energy because they’d lose all that helpful lightbulb heating in the winter–a stretch that even Gumby would envy.

  31. #31 Dano
    June 5, 2009

    Oddly, these efforts seemed to disappear in the new decade, as if something had somehow changed…

    Trollhattan, it’s not disappearing.. I am traveling very soon to present a paper on UHIs and strategies for abatement.

    A lot of this work got pushed down to local jurisdictions, where they don’t have the funding and have to rely on ‘education and markets’ to get something done.



  32. #32 Dave Andrews
    June 5, 2009

    Dano #21,

    But hasn’t Phil Jones, of HADCRU, and provider of temperature records to the IPCC, gone on record in the past and said UHI makes no difference?

  33. #33 pough
    June 5, 2009

    No difference to what? Warming effects of albedo and the effect of albedo on the recording of temperature anomaly over time are two different things, aren’t they? Do you not understand the difference?

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