Maybe now NOAA will get rid of all remaining rooftop climate monitoring stations or stations sited over asphalt, like this one. As for the carbon emissions issue, that remains to be seen.
Global Model Confirms: Cool Roofs Can Offset Carbon Dioxide Emissions and Mitigate Global Warming
Can light-colored rooftops and roads really curb carbon emissions and combat global climate change? The idea has been around for years, but now, a new study by researchers at Lawrence Berkeley National Laboratory that is the first to use a global model to study the question has found that implementing cool roofs and cool pavements in cities around the world can not only help cities stay cooler, they can also cool the world, with the potential of canceling the heating effect of up to two years of worldwide carbon dioxide emissions.
Because white roofs reflect far more of the sun’s heat than black ones, buildings with white roofs will stay cooler. If the building is air conditioned, less air conditioning will be required, thus saving energy. Even if there is no air conditioning, the heat absorbed by a black roof both heats the space below, making the space less comfortable, and is also carried into the city air by wind—raising the ambient temperature in what is known as the urban heat island effect. Additionally, there’s a third, less familiar way in which a black roof heats the world: it radiates energy directly into the atmosphere, which is then absorbed by the nearest clouds and ends up trapped by the greenhouse effect, contributing to global warming.
Today, U.S. Energy Secretary Steven Chu announced a series of initiatives at the Department of Energy to more broadly implement cool roof technologies on DOE facilities and buildings across the federal government. As part of the effort to make the federal government more energy efficient, Chu has directed all DOE offices to install cool roofs, whenever cost effective over the lifetime of the roof, when constructing new roofs or replacing old ones at DOE facilities. Additionally, the Secretary has also issued a letter to the heads of other federal agencies, encouraging them to take similar steps at their facilities.
“Cool roofs are one of the quickest and lowest cost ways we can reduce our global carbon emissions and begin the hard work of slowing climate change,” said Chu. “By demonstrating the benefits of cool roofs on our facilities, the federal government can lead the nation toward more sustainable building practices, while reducing the federal carbon footprint and saving money for taxpayers.”
In the latest study, the Berkeley Lab researchers and their collaborators used a detailed global land surface model from NASA Goddard Space Flight Center, which contained regional information on surface variables, such as topography, evaporation, radiation and temperature, as well as on cloud cover. For the northern hemisphere summer, they found that increasing the reflectivity of roof and pavement materials in cities with a population greater than 1 million would achieve a one-time offset of 57 gigatons (1gigaton equals 1 billion metric tons) of CO2 emissions (31 Gt from roofs and 26 Gt from pavements). That’s double the worldwide CO2 emissions in 2006 of 28 gigatons. Their results were published online in the journal Environmental Research Letters.
“These offsets help delay warming that would otherwise take place if actual CO2 emissions are not reduced,” says Surabi Menon, staff scientist at Berkeley Lab and lead author of the paper.
Co-author Hashem Akbari emphasizes that cool roofs and pavements are only a part of the solution: “Two years worth of emissions is huge, but compared to what we need to do, it’s just a dent in the problem,” says Akbari, the former head of the Berkeley Lab Heat Island Group and now Hydro-Quebec Industrial Research Professor at Concordia University in Montreal. “We’ve been dumping CO2 into the atmosphere for the last 200 years as if there’s no future.”
This study is a follow-up to a 2008 paper published in the journal Climate Change, which calculated the CO2 offset from cool surfaces by using a simplified model that assumed a global average for cloud cover. The earlier paper, co-authored by Akbari, Menon and Art Rosenfeld, a Berkeley Lab physicist who was then a member of the California Energy Commission, found that implementing cool roofs and pavements worldwide could offset 44 gigatons of CO2 (24 Gt from roofs and 20 Gt from pavements).
Equivalent to Getting 300 Millions Cars Off the Road
“If all eligible urban flat roofs in the tropics and temperate regions were gradually converted to white (and sloped roofs to cool colors), they would offset the heating effect of the emission of roughly 24 Gt of CO2, but one-time only,” says Rosenfeld, who returned to Berkeley Lab this year. “However, if we assume that roofs have a service life of 20 years, we can think of an equivalent annual rate of 1.2 Gt per year. That offsets the emissions of roughly 300 million cars (about the cars in the world) for 20 years!”
In both studies, the researchers used a conservative assumption of increasing the average albedo (solar reflectance) of all roofs by 0.25 and of pavements by 0.15. That means a black roof (which has an albedo of 0) would not have to be replaced by a pure white roof (which has an albedo of 1), but just a roof of a cooler color, a scenario that is more plausible to implement.
[2]Lighter colored pavement is more reflective, resulting in a cooler surface temperature. (Photo courtesy ASU National Center of Excellence for SMART Innovations)
Roofs and pavements cover 50 to 65 percent of urban areas. Because they absorb so much heat, dark-colored roofs and roadways create what is called the urban heat island effect, where a city is significantly warmer than its surrounding rural areas. This additional heat also eventually contributes to global warming. More than half of the world’s population now lives in cities; by 2040 the proportion of urbanites is expected to reach 70 percent, adding urgency to the urban heat island problem.
The Berkeley Lab study found that global land surface temperature decreased by a modest amount—an average of roughly 0.01degrees Celsius, based on an albedo increase of .003 averaged over all global land surfaces. This relatively small temperature reduction is an indication that implementing cool surfaces can be only part of the solution to the global climate change problem, the researchers say. To put the number in context, consider that global temperatures are estimated to increase about 3 degrees Celsius in the next 40 to 60 years if CO2 emissions continue rising as they have. Preventing that warming would necessitate a 0.05 degree Celsius annual decrease in temperature between now and 2070.
Thus, even modest changes should not be dismissed. “Simply put, a cool roof will save money for homeowners and businesses through reduced air conditioning costs. The real question is not whether we should move toward cool roof technology: it’s why we haven’t done it sooner,” says Rosenfeld.
Other Studies Reach Similar Conclusions
Another recent study on cool roofs, led by Keith Oleson at the National Center for Atmospheric Research (NCAR) and published in Geophysical Research Letters, found that if every roof were painted entirely white, the CO2 emission offsets would be approximately 32 Gt for summer and about 30 Gt annually. While the NCAR study used a different model, the calculated CO2 emission offsets are similar to the results from the Berkeley Lab study and provide a useful and independent verification of the expected CO2 emission offsets from increasing the reflectivity of roofs.
Some observers have pointed out that cool roofs do not make sense in cooler climates because of “winter penalties,” since cooler buildings require more energy to heat. However, the energy savings from cooler buildings usually outweighs any increase in heating costs. Furthermore, in winter, there tends to be more cloud cover; also, the sun is lower and the days are shorter, so a flat roof’s exposure to the sun is significantly reduced.
“Cool roofs have worked for thousands of years in the Mediterranean and Middle Eastern cities, where demand for air conditioning is low,” says Akbari. “If you have a cool roof on your house, that will reduce your energy use from air conditioning and it’s a gift that keeps on giving for many, many years, for the life of the roof.”
Berkeley Lab is a U.S. Department of Energy national laboratory located in Berkeley, California. It conducts unclassified scientific research for DOE’s Office of Science and is managed by the University of California. Visit our website at www.lbl.gov/ [3].
[4]The surface of a black roof (left) heats up 78F above the air temperature, while the surface of a white roof (right) heats up only 12F. Additionally, with a black roof, far more heat flows both to the city and into the atmosphere (arrow lengths are proportional to energy radiated).
Additional information:
- Read the DOE Cool Roofs annnouncement here [5].
- Video glossary entry: Cool Roof [6]
- Read the 2010 paper by Surabi Menon, Hashem Akbari, Sarith Mahanama, Igor Sednev and Ronnen Levinson, “Radiative forcing and temperature response to changes in urban albedos and associated CO2 offsets” [7]
- Download the 2008 paper by Hashem Akbari, Surabi Menon and Art Rosenfeld, “Global cooling: increasing world-wide urban albedos to offset CO2” here [8].
Article printed from Berkeley Lab News Center: http://newscenter.lbl.gov
URL to article: http://newscenter.lbl.gov/news-releases/2010/07/19/cool-roofs-offset-carbon-dioxide-emissions/
URLs in this post:
[1] Image: http://newscenter.lbl.gov/wp-content/uploads/roof-solano-gov-center-CEC.jpg
[2] Image: http://newscenter.lbl.gov/wp-content/uploads/Cool-Pavement-ASU.png
[3] www.lbl.gov/: http://www.lbl.gov/
[4] Image: http://newscenter.lbl.gov/wp-content/uploads/White-Roof-Alliance-single-10.png
[5] here: http://energy.gov/news/9225.htm
[6] Cool Roof: http://videoglossary.lbl.gov/2009/cool-roof/
[7] “Radiative forcing and temperature response to changes in urban albedos and associated CO2 offsets”: http://www.iop.org/EJ/article/1748-9326/5/1/014005/erl10_1_014005.html
[8] here: http://www.energy.ca.gov/2008publications/CEC-999-2008-020/CEC-999-2008-020.PDF
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Paul Linsay says:
July 19, 2010 at 1:22 pm
“This has been done on the Mediterranean since forever and for the same reason.”
Are you 100% sure? I thought that whitewash was used because you could see when it needed replacing to reduce structural crumbling. After all, what else of convenience was there to paint onto the buildings in the early days?
Russell Seitz says:
July 20, 2010 at 3:30 pm
Use titanium dioxide, the whitest white.
Sorry, Russell, there just ain’t nearly enough TiO2 to go round economically. It also takes enormous energy to strip out the last bits of omnipresent iron, which cause it to go brown in the weather.
That’s an interesting cartoon with the arrows in the lead story. Especially the un-named yellow arrow to the right, which suddenly gets bigger. What if it shines onto a taller adjacent building? What if it gets sucked down an air conditioner inlet and requires more fuel to make the air conditioner achieve low temperature?
Remember, the incoming sunlight does not know the colour of the roof. It’s the unstated wavelength band of that yellow arrow that is missing from the cartoon. What is it?
Geoff Sherrington says:
“… what else of convenience was there to paint onto the buildings in the early days?”
Ochre. Mud. Cement. Dung. Sand (with a binder, eg dung). They’ve all been used. Whitewash is probably the most convenient, though.
“Sorry, Russell, there just ain’t nearly enough TiO2 to go round economically. It also takes enormous energy to strip out the last bits of omnipresent iron, which cause it to go brown in the weather.”
There’s more than enough titanium to paint a sphere the size of Earth’s orbit. The energy required to make the TiO2 is a minuscule fraction of the reduction in energy absorbed to the environment over the paint’s life; at a very rough estimate, payback time ~1000s (~100MJ/kgTi, 1gTi/m2, 100W/m2 less sunlight absorbed).
” It’s the unstated wavelength band of that yellow arrow that is missing from the cartoon. What is it?”
It’s sunlight! It’s the light reflected back into space by the white surface that would otherwise have been absorbed by the black surface.
Paul Birch writes: “What a snarky remark. If this alleged climatologist claims that atmospheric pressure has been changing significantly over the past thirty years, as you imply, then I’d say either he knows something vital that no one else does or he knows squat…”
Listen Birch, that was no snarky remark.
From Wiki:
“Leroux demonstrated through the analysis of synoptic maps, satellite imagery, meteorological and palaeoenvironmental data over Tropical Africa that the seasonal and palaeoclimatic migration of the Meteorological Equator represents a reliable proxy of the Earth’s climate evolution [Leroux M. (1983). PhD. Thesis : Le climat de l’Afrique tropicale. Ed. H. Champion/M. Slatkine, Paris/Genève, t.1. : 636 p., 349 fig., t. 2 : notice et atlas de 250 cartes], [“The Meteorology and Climate of Tropical Africa”, Springer Verlag, Springer-Praxis books in Environmental Sciences, London, NY, 548 pp + CD: 300 pp, 250 charts, 2001, ISBN: 978-3-540-42636-3].
This migration and the extent of the Meteorological Equator are the consequence of continuous meridional exchanges in the denser, lower layers of the atmosphere, which circulation is governed by the incessant ballet of the Mobile Polar Highs or Anticyclone Mobile Polaire, 1.5km high, 3,000 km diameter discoid, lenticular cold air-masses anticyclones originating from the poles, whose strength and frequency depends directly on the thermal polar deficit. Cooling spurns an accelerated circulation while warming will slow the general circulation and exchanges [“The Mobile Polar High: a new concept explaining present mechanisms of meridional air-mass and energy exchanges and global propagation of palaeoclimatic changes” Marcel Leroux, Global and Planetary Change, 7 (1993) 69-93 Elsevier Science Publishers B V, Amsterdam].
The aerological spaces of circulation, zones of continuous circulation from the pole to the equator are bound by relief over 2,000m and the present position of continents. In light of direct observations [Leroux M. (1983). PhD. Thesis : Le climat de l’Afrique tropicale. Ed. H. Champion/M. Slatkine, Paris/Genève, t.1. : 636 p., 349 fig., t. 2 : notice et atlas de 250 cartes.], [“Dynamic Analysis of Weather and Climate Atmospheric Circulation, Perturbations, Climatic Evolution”, Springer-Praxis books in Environmental Sciences, 2nd ed., 2010, 440p., ISBN: 978-3-642-04679-7 ], Leroux’s reconstruction exposes the inconsistencies of previous general circulation models, of oscillation indexes and of frontological, dynamical, reductionist and diagnostic schools of Meteorology. This made him a controversial figure.
In doing so, Leroux refutes the artificial separation between Meteorology and Climatology and through the MPH concept, redefines both disciplines in a similar way Plate Tectonics revolutionized Earth Sciences in the 1960s. He reconstructed the geometry of the troposphere general circulation [“The Mobile Polar High: a new concept explaining present mechanisms of meridional air-mass and energy exchanges and global propagation of palaeoclimatic changes” Marcel Leroux, Global and Planetary Change, 7 (1993) 69-93 Elsevier Science Publishers B V, Amsterdam] and demonstrated that very little is owed to hazard or chaos: there is no ‘unruly climate’ but intensity shifts of the sum of weather processes that constitute the climate.
This research confirmed that the climatic shift observed since the 1970s corresponds to the setting of an accelerated mode of circulation, always associated with cooling during the late Quaternary palaeoclimatic evolution, and its meteorological consequences: contrasted weather, stronger mid-latitude storms, increase water vapour in the troposphere and impermanent anticyclonic stability over continents leading to vigorous cold snaps in winter and heatwaves in summer [“Dynamic Analysis of Weather and Climate Atmospheric Circulation, Perturbations, Climatic Evolution”, Springer-Praxis books in Environmental Sciences, 2nd ed., 2010, 440p., ISBN: 978-3-642-04679-7].
In consequence, his results refute the validity of a Global Mean Temperature curve as a major climatic proxy and contradict the assumption that weather changes observed in the second half of the XX Century were the consequence of an Anthropogenic Global Warming climatic change brought by the release of greenhouse gases due to industrial and human activities [“Global Warming: Myth or Reality? The Erring Ways of Climatology”, Springer-Praxis books in Environmental Sciences, Berlin, Heidelberg, London, New- York, 509p., 2005, ISBN: 978-3-540-23909-3].
Furthermore, his work provides the meteorological mechanism for past glaciations and de-glaciations, improves meteorological prediction models and climate simulation accuracy in constraining them through the real geometry of atmospheric circulation, its discontinuities, energy exchanges and their associated clouds [“Dynamic Analysis of Weather and Climate”, J. Wiley ed. Praxis-Wiley series in Atmospheric Physics, London, NY, 365 pp, 1998].
In his approach, Leroux was a true disciple of Descartes and his books are highly didactic. The English 2nd edition of “Dynamic Analysis of Weather and Climate, Atmospheric Circulation, Perturbations, Climatic Evolution” was completed in 2008 two months before his passing and published in January 2010 [“Dynamic Analysis of Weather and Climate Atmospheric Circulation, Perturbations, Climatic Evolution”, Springer-Praxis books in Environmental Sciences, 2nd ed., 2010, 440p., ISBN: 978-3-642-04679-7].”
So Birch had you simply bothered to search you’d have found that my comment related to the increasing strength of anticyclones -rapid mode of circulation-, pushing towards the ME in both hemispheres and on the path of which over time mean atmospheric pressure have been measured rising for the past 40 years. Correlatively associated depressions have been deepening.
Before disparaging you could have also asked me to clarify the context of my comment.
EOM.
TomRude says:
July 21, 2010 at 8:34 am
“Listen Birch, that was no snarky remark. … Before disparaging you could have also asked me to clarify the context of my comment.”
I did. Your snarky remark was in response to my request for clarification.
Pasting a big chunk from wiki is not scientific argument, especially since it didn’t even mention the atmospheric pressure that you claim has risen enough over thirty years to make previously appropriate architectural design no longer appropriate. Which is plain daft – do you think architects change their house designs just because they’ve gone a few yards along the road to where it’s a foot higher? Buildings have to cope with the wide extremes of weather. A small shift in the bias or average or frequency of that weather within its normal fluctuations has essentially no impact on the design. Even a big shift may not matter much; a house from Northern Scandinavia will probably do just fine in Southern California.
Theoretically, a marginal shift in eg average temperature could make a marginal shift in economically optimum insulation levels, etc., but in practise architects simply don’t work to such tiny tolerances (and almost all buildings could benefit from more insulation anyway). Other factors, such as solar gain, depend on the building’s latitude, which doesn’t change (or only very very slightly, with nutation, continental drift, etc.).
Birch writes: “Pasting a big chunk from wiki is not scientific argument, especially since it didn’t even mention the atmospheric pressure that you claim has risen enough over thirty years to make previously appropriate architectural design no longer appropriate…”
Really, your knowledge about atmospheric circulation and its affect on weather leaves much to be desired. I never said that it was the rise in pressure that made house designs obsolete but the rise of pressure that accompanied an evolution of weather over an region, bringing anticyclone permanence, and thus would be reflected by heatwaves in summer and cold waves in winter, i.e. more extreme weather more often. Thus a building designed for a more temperate climate would be strained in a more continental climate. This quite different than your “Which is plain daft – do you think architects change their house designs just because they’ve gone a few yards along the road to where it’s a foot higher?”
And I do not claim, it has been MEASURED (CDC/NCEP-NCAR data). Unless of course you have nothing to learn from anyone… and That is a snarky final remark.
TomRude:
You certainly did claim that increasing atmospheric pressure had made achitectural designs obsolete. You said, “…
that has increased the contrast between seasons over the past 30 years through rising atmospheric pressures…” (my emphasis).
Slight changes in atmospheric pressure cannot significantly “increase the contrast between seasons”. It is physically nonsensical. We are talking about variations at the 0.01% (0.1mbar) level, which, if they related directly to seasonal temperature differences would affect the seasonal peaks by only ~0.001 degree! Negligible. Moreover, to the extent that there is any effect at all, the sign is the opposite to that which you claim: in planetary science thicker atmospheres mean less seasonal variation, not more. Slight changes in atmospheric pressure are the (insignificant) consequence of changes in climate, not the cause.
In any case, whatever the causes, climate simply hasn’t changed very much in the past thirty years – not remotely enough to make previously suitable building designs obsolete. I don’t need fancy measurements to tell me that (though they confirm it very strongly). Just looking at the buildings and remembering is enough.
Looking at the literature on black body radiation, it seems to to me to be scientifically agreed that in a black painted box, the black painted exterior surface absorbs heat and simultaneously radiates heat to the inside of the box, so the box gets warmer.
It also appears that the study of white body radiation is not nearly as sexy as black, (why, I have no idea) with the result that not much appears to be written up on it.
OK.
So my black painted bungalows in Panama scientifically absorbed solar heat which scientifically made the rooms warmer, whether other commenters agree or not.
As no scientific work has been done on white body radiation, we can only assume that white body radiation doesn’t, at the moment exist, that is, it cannot be scientifically proven.
In this case we do not really know whether the bungalow rooms in Panama got cooler or didn’t, sort of Schrodinger rooms.
Or white magic perhaps.
Anyway, we got cooler rooms.
Funny, that.
Paul Birch writes: “We are talking about variations at the 0.01% (0.1mbar) level,…”
OK you know better.
CDC/NCEP-NCAR data, evolution of mean annual surface pressure, period 1948-2002:
Vigouroux 2004, Lake Constance from 1015 to 1019mb
Pommier 2004, mediterranean basin, Cairo, Ghadames from 1013 to 1016mb
Pommier 2002 central France from 1015 to 1017mb
LCRE Dakar, from 1011 to 1012.5mb
Barbier 2004 Panama from 1009 to 1011.5mb
Gobi desert China, from 1014 to 1019mb
Zones of associated depressions trajectories show deepening of these depressions over the same period. The frequency of these is increasing too.
0.1mb… yeah right!
From the article:
“Cool roofs are one of the quickest and lowest cost ways we can reduce our global carbon emissions and begin the hard work of slowing climate change,” said Chu.
DO TELL: If all of the electrical energy used to either heat or cool a building is derived from either water or nuclear power, then how in the name of all that good and proper, will a white roof reduce the carbon in the atmosphere?
That is right on par with painting the Andes white …
Next, I’ll presume that GISS, et al., will commence to say that parking the temperature measurement instruments is quite okay on white roofs, right?
Well, let me ask: Has anyone ever done the science to determine the actual difference between the temperatures experienced on white vs black roofs vs a properly located Stevenson Screen?
This whole scheme is one of deflection away from the central core of an extremely faulted premise: Human-caused GW.
They can’t prove their assertion, so instead of admitting having wasted literally BILLIONS of dollars pushing a lie, they now engage in taking advantage of the very crisis which they themselves created: Never let a good crisis go to waste!
The team who did the ‘Hide the Decline’ video, now now needs to do a sequel: ‘Pushing a Lie.’
TomRude says:
July 21, 2010 at 6:46 pm
Paul Birch writes: “We are talking about variations at the 0.01% (0.1mbar) level,…”
OK you know better.
_________________________
I know on hard physical grounds (conservation of mass!) that the secular change in atmospheric pressure cannot be more than that order of magnitude. If alleged measurements purport to show otherwise, they are wrong. I suspect that you simply don’t understand what is being measured or described. At any place, local atmospheric pressure swings wildly – by up to ~50mbar – due to weather. Because of this, if you try to measure the mean atmospheric pressure there, it will be highly uncertain. The statistics are messy, because the distribution is long-tailed, but for a maritime climate outside the tropics, one might expect to get within a few mbar over one year. Over thirty years one could gain another factor of two or three. Elsewhere, the accuracy will be even less, because with longer-lived or fewer weather patterns there are fewer independent datapoints. The error bars are far larger than any real secular variation. Only by combining a large number of simultaneous readings across the globe, within and without each weather pattern (cyclonic or anticyclonic), could one improve the accuracy enough to see the changes due to more/less water vapour, release/absorption of CO2 etc. “Standard atmospheric pressure” is defined as 101325N/m2, but I doubt whether the global measurement accuracy really justifies the last few places.
Paul Birch says:
July 21, 2010 at 7:06 am
Plenty of TiO2?
At one stage our parent company owned a part of subsidiary named Rutile and Zircon Mines, near Tomago, Australia. It was a world scale producer. Rutile is like TiO2 with a lot of natural iron in it. It is the removal of the iron that takes huge energy. I managed a large pilot plant one year that tried just that. The next hurdle is to get permission to mine for rutile or anastase or whatever the mineral form might be, for much of it is in beach sands and we don’t want to mine them any more, do we? We’d chortle with joy if rising oceans reduced their economic value to nil.
Why do people like you get masochistic delight from gloomy predictions?
Finally, I’m not going to indulge in discussion about meaningless calculations about paint areas, when I stressed that “economically” there is not enough TiO2 to go round. And you did not address my point about where the reflected heat went, maybe onto the building next door, maybe down an adjacent air conditioner inlet. Maybe some even goes up into the sky and returns after bouncing off clouds. So what wavelength band do you imagine the yellow arrow light covers, in common units like microns? Or do you not know? It’s a fairly important question in the balance of energy.
Try the KISS principle instead of making up numbers.
OK Paul Birch, we must be talking about two different things: I am talking about weather related atmospheric pressure trends because in the end this is what’s we are here interested in since climate is the sum of weathers (how many times did I mention that associated depressions were deeper?). You, on the other hand, must be talking about a global atmospheric pressure.
In any case, my suggestion to read “dynamic analysis of weather and climate” was genuine and not snarky. EOM
Geoff Sherrington says:
July 22, 2010 at 6:18 am
Paul Birch says:
July 21, 2010 at 7:06 am
Plenty of TiO2?
“It is the removal of the iron that takes huge energy.”
Only huge relative to the 19MJ/kgTi enthalpy for the reduction of TiO2 to Ti. Even thirty years ago, a figure of ~800MJ/kgTi was typical. There were many inefficiencies in that process, so I have little doubt that my figure of 100MJ/kgTi would be achievable for large-scale production. NASA SP-428 considers a variety of production processes for the space manufacturing facility utilising lunar ilmenite concentrate with 48%TiO2, 43%FeO, from bulk mare soil, which despite being far inferior as an ore to rutile would permit the extraction of a nominal 20,000 tons a year at an energy cost well under 100MJ/Ti, with co-production of a similar quantity of iron. Recycling the sensible heat in the reaction products would improve on this further.
“Why do people like you get masochistic delight from gloomy predictions?”
!!! You’re the one making gloomy predictions – that there wouldn’t be enough white paint! I’m saying that, on the contrary, there is ample energy and more than ample raw materials. If demand for TiO2 increases, then, over the medium and long term as new plants come into operation, the real cost will fall.
“And you did not address my point about where the reflected heat went”
Yes, I did. It goes back into space! That’s what albedo means – the fraction reflected back into space. The fact that not quite all of the reflected light makes it back out is part of the reason for the conservative figure they used for the increase in albedo. And it’s not reflected heat. It’s reflected sunlight.
“So what wavelength band do you imagine the yellow arrow light covers, in common units like microns? Or do you not know? It’s a fairly important question in the balance of energy. Try the KISS principle instead of making up numbers.”
It’s sunlight! I don’t know how to put it any simpler than that. Black body radiation at a temperature ~6000K, most of the energy lying between ~0.2 micron and ~1 micron, with the peak in the yellow around half a micron. Thermal radiation at ~300K is of much longer wavelength ~10 micron; at those wavelengths radiator paint and TiO2 are nearly black.
TomRude says:
July 22, 2010 at 8:39 am
OK Paul Birch, we must be talking about two different things: I am talking about weather related atmospheric pressure trends because in the end this is what’s we are here interested in since climate is the sum of weathers (how many times did I mention that associated depressions were deeper?). You, on the other hand, must be talking about a global atmospheric pressure.
In any case, my suggestion to read “dynamic analysis of weather and climate” was genuine and not snarky. EOM
_________________________________________________________________
OK. If you’re talking about local atmospheric pressures, not global, then for every locality with an increase in pressure there must be another with a corresponding reduction in pressure. They can’t all be on a rising trend. That would be rather like this winter, when everyone was cold but, magically, the global temperature was said to be hot! Even locally, one simply cannot obtain a significant measure of atmospheric pressure trend over thirty years; the statistical fluctuations are far too intractable; you can calculate an average trend line over the period if you like, but it doesn’t mean anything. Even if it did mean something, the figures you gave are still far too small to have any impact on building design (still less than 40m of equivalent altitude). Nor would it have any significant effect on the weather; within quite wide limits, the absolute atmospheric pressure doesn’t matter.
If you simply mean that weather extremes have become more severe, then talk of atmospheric pressures is a red herring. Even there, I would not accept that weather has become more extreme over the past thirty years. You can always cherry-pick locations where it appears to have, but I have also seen studies showing less extreme weather. Again, the natural variability of weather – and the long-tailed nature of the frequency distributions – means that we just can’t distinguish such local apparent trends from pure chance.
Moreover, to come back to the crucial point you seem to be ignoring, suppose that deeper depressions were more frequent; in these locations, buildings are already designed to cope with such depressions. They have to be, because they’re already a common enough feature of the climate. So buildings that had appropriate architectural designs before would still be appropriate; and ones that were inappropriate would still be inappropriate. There would have to be a quite drastic – and implausible – extension of the absolute weather extremes (in severity not just frequency) for there to be any real need to adapt building design to changing conditions. Certainly nothing of the sort has yet happened anywhere.
“They can’t all be on a rising trend.” Indeed we agree.
As for building designs that would be interchangeable from Sweden to Arizona, one truly wonders why we’d have different designs over centuries if one house could fit all.
“If you simply mean that weather extremes have become more severe, then talk of atmospheric pressures is a red herring. Even there, I would not accept that weather has become more extreme over the past thirty years.”
Based on what? Really you would benefit from reading the reference I invited you to explore before you go on over extending yourself on meteorology and climatology.
TomRude says:
July 22, 2010 at 1:10 pm
“As for building designs that would be interchangeable from Sweden to Arizona, one truly wonders why we’d have different designs over centuries if one house could fit all.”
You truly wonder over something so obvious? Technology changes. Society changes. Wealth changes. Fashions change. Laws change. Government policies change. Resources change. And personal preferences vary. That’s why houses aren’t all the same.
Climate change doesn’t even make it onto the list.
Do you seriously doubt that a well-made modern house from Northern Scandinavia would still work in the climate of Southern California (or Arizona, if you prefer)? There is actually a strong export market for Swedish “flat pack” houses across the developed world (including the southern US). As I keep trying to point out to you, the most important building design features are sturdy construction and good insulation – and those are appropriate in every climate. Taking into account solar gain, different designs may be optimal at different latitudes (though Roman Villas are much the same whether in the Med or up by Hadrian’s Wall), but this does not change with epoch; it is not subject to “climate change”.
I said, “If you simply mean that weather extremes have become more severe, then talk of atmospheric pressures is a red herring. Even there, I would not accept that weather has become more extreme over the past thirty years.”
You said, “Based on what?”
I had already answered that in the next two sentences “You can always cherry-pick locations where it appears to have [become more severe], but I have also seen studies showing less extreme weather. Again, the natural variability of weather – and the long-tailed nature of the frequency distributions – means that we just can’t distinguish such local apparent trends from pure chance.” I could also have added, personal observation. You seem strangely unwilling to accept just how radically variable – and unpredictable – “normal” weather is.
Do the fools presenting this idea as a solution ever THINK of the many of the same roofs in the hot summer (requires white roofs and white streets solution Chu is gibbering about) are in the SAME PLACE as areas that require black roofs and black streets to melt the winter snow and ice, keep the same buildings warmer in the winters?
Temperatures vary – a lot. Summer temp’s across most of the physical US vary from low 100’s (F) to low 90’s. (If there WERE REALLY an economic advantage of painting a building’s roof white – then the OWNER should be the one doing it. For the owner’s benefit, the owner’s savings in cooling costs. That there is NO financial reason to do so tells me that Chu is wrong. Dead wrong. That, or the need for each owner to do something else (maybe fix something that really needs fixing, or paying somebody’s salary, or buying paper, or buying ink, or buying a congressman’s vote ) is more important tot hte INDIVIDUAL owner . In every case in the real world – painting the roof white fails the “will it pay off?” test.
Across the same area, winter temps very from -15 (F) to +20 and +30 (F) – Winter heating (eased by black roofs) and winter snow removal (simplified by black streets melting tons of ice and small falls by mid-morning and the next day) allow most of the country to simply ignore snow days and snow storms. So, who is going to pay (and re-pay, and re-pay, and re-pay) for “painting the streets white” (and – er, celaning them again when tire black and tire residue make them gray again) ?)
The “ideal” of “we’re going to solve this problem” (which doesn’t exist) by spending (wasting) millions of dollars that will cost money the next season seems to have completely skipped his ignobel-filled mind.
Amazingly you need not to learn from anybody Paul Birch even when you clearly are out of your depth. You know it all: is the Nobel forthcoming or just “been there, done that”? Need not replying: we already figured out the answer. Bye.
While it is remotely possible that someone may be able to develop an economical thermochromatic roofing material that might be black in cold weather and white or silver in hot weather, I think people would not be prepared to see the exterior walls of their homes or their roadways changing color this way.
Example: Thermochromatic Mugs from QOOP
TomRude says:
July 22, 2010 at 7:25 pm
Amazingly you need not to learn from anybody Paul Birch even when you clearly are out of your depth. You know it all: is the Nobel forthcoming or just “been there, done that”? Need not replying: we already figured out the answer. Bye.
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Suppose you address the actual science and rational arguments instead of making absurd personal attacks and relying upon appeals to (nonexistent) authority.
RACookPE1978 says:
July 22, 2010 at 5:03 pm
“Do the fools presenting this idea as a solution ever THINK of the many of the same roofs in the hot summer (requires white roofs and white streets solution Chu is gibbering about) are in the SAME PLACE as areas that require black roofs and black streets to melt the winter snow and ice, keep the same buildings warmer in the winters?”
This topic has been discussed, on this and earlier threads. First, there are many places that would benefit from cooling in summer and do not have a snow problem in winter; still others where the heat of summer is a more serious problem than the snow in winter; still others where it’s the other way round and they would benefit more from warming. It’s not one size fits all. Places that would benefit from both cooling in summer and warming in winter can be improved by maximising the amount of greenery, which mitigates both extremes. Thermosensitive paint and adaptive roof structures have also been mooted.
“If there WERE REALLY an economic advantage of painting a building’s roof white – then the OWNER should be the one doing it. For the owner’s benefit, the owner’s savings in cooling costs. That there is NO financial reason to do so tells me that Chu is wrong. ”
Adjusting the albedo of a city is an example of a “public good”, in which the individual property owner captures only a small fraction of the benefit of his investment, but also benefits from the investments made by everyone else. Most of the economic benefit comes in the form of positive externalities.
“… simplified by black streets melting tons of ice and small falls by mid-morning and the next day…”
I wonder whether anyone has measured the benefit of dark roads on snow and ice removal? It’s not as straightforward as one might think. My experience in the UK suggests that the primary snow removal mechanism is the movement of traffic, churning it into slush and pushing it to the sides of the road. The colour of the road under the snow doesn’t make any difference until the road surface has been exposed, when the snow at the edges does melt faster over black tarmac. Roads with light tarmac and concrete do not seem to suffer from snow retention any more than the roads in black tarmac (for equivalent traffic volumes). Bear in mind that snow falls from leaden skies, when there’s no significant solar gain to black surfaces. I would also say that black tarmac seems somewhat more likely to suffer dangerous iceing, perhaps because snow or frost melts, then refreezes, or perhaps only because black tarmac surfaces tend to be smoother.
“painting the streets white” (and – er, celaning them again when tire black and tire residue make them gray again) ? ”
I don’t think anyone wants to paint the roads pure white. In the past few days I’ve made a note of the local road surfaces. A surprising percentage of the roads are in various light tarmacs. Not merely the pigmented asphalts used as top dressings at junctions, etc., and which have a slight cost premium, but also cheaper sorts in which the bitumen flows or is washed away from the top of the stones, leaving them proud of the surface and showing their natural colours. Any tire residue or skid marks also wash off. These light tarmacs are actually pleasanter to drive on (at modest urban speeds) than smooth black tarmac.
One should keep in mind that a dark, high emissivity road surface is also more prone to radiative cooling at night in the winter, as those who may have had the misfortune to encounter ‘black ice’ at high speed may know only too well.
So question to DOE policymakers:
Will the DOE facilities in northern areas be allowed to substitute warm roofs (black, I suppose) in place of cool roofs? Off the top of my head:
– Idaho National Energy Laboratory (INEL) near Idaho Falls, ID
– Knolls Atomic Power Lab (KAPL) in Schenectady, NY
I can’t imagine looking someone in the eye who works at either of those two and telling them they need to make a cooler roof. Aside from the personal anguish associated with giving this news, it would probably save more energy on heating than it necessitated in cooling.
Sorry to any DOE-ites who also work and the frigid north. Those 2 were just the best 2 examples I could think of off the top of my head. I know it gets cold at Argonne, but that’s basically Chicago so it doesn’t count. 🙂