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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

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    • CommentAuthortony
    • CommentTimeFeb 7th 2013 edited
     
    Thanks Ed,

    I like your persuasive approach and thank you for trying to explain such complex things in such detail for me. I also like the several different “thought experiment” worlds that you used brilliant!

    I am not sure that I explained myself well enough on the Stefan’s Law stuff, the earth when viewed from outside is orbiting in space which apart from the sun is at almost absolute zero, we are kept warm by the sun and loose heat to space. Stefan’s law tells us that the heat lost is proportional to the fourth power of the absolute temperature and so as the temperature of the planet rises so more heat is lost. The effective radiative temperature of the earth is the average glow from the earth that can be seen from space and is related to our overall heat lost. The overall heat gained vs heat lost equation for the planet as a whole must balance and is :- (1-a) S~r2 = 4~r2eoT4 The term T4, the fourth power of the absolute radiative temperature, is a very heavy term in this balancing act, even the difference between two fourth powers of two fairly similar Kelvin temperatures still frighteningly large both in percentage terms and in the sheer amount of energy represented. I like to think of most of the other terms in the equation as fairly stable and not subject to huge percentage changes over the timespan of years or decades. The terms e and o already include the greenhouse effect.

    I have said that I cannot see how any model that has regard to this equation can predict exponential or even increasingly rapid temperature rises (the typical hockey stick graphs we have all seen). It is for this reason alone that I am unhappy with the models that show these types of increases.

    Yes there are enormous complexities in the atmosphere but none of these can cut against Stefan’s Law. Yes the temperature of the planet has risen a little but the reason for this in not proven, it could be being caused by any one or combination of many different variables and the rises in the levels of CO2 could even be an effect of these rises rather the cause of them were the rises to be due to some other factor. To attribute the whole of the rise in temperature only to greenhouse gasses is unlikely to be correct and without knowing the magnitude of this in relation to any other drivers leaves us almost guessing which of the drivers is having the most major effect.

    I know that I do not understand the complexities of climate modelling but would be happy to see direct evidence of the link between increased carbon dioxide levels and rising temperatures and also an explanation of “hockey stick” type predictions.
    • CommentAuthorEd Davies
    • CommentTimeFeb 7th 2013
     
    Longer answer, particularly to your final points, later but for the moment: as you say, the effective radiative temperature of the whole planet can't change much. However, the point of my little essay is that that temperature applies quite a few kilometres up, not down on the surface where we live. It's the difference between the temperatures at the effective radiation level and the surface which is increased by the greenhouse effect.
    • CommentAuthorEd Davies
    • CommentTimeFeb 8th 2013 edited
     
    Posted By: tony: “...and the rises in the levels of CO2 could even be an effect of these rises rather the cause of them were the rises to be due to some other factor.”

    This is the bit of your “belief system” I find hardest to understand. We know pretty well how much CO₂ we're emitting (just convert millions of tonnes of oil and coal to moles and do the arithmetic and add a bit more for the estimated amount of deforestation). It matches well with the atmospheric increases with 40% or a bit more of that CO₂ staying in the atmosphere, the rest going into the soil, plants, ocean and so on.

    The first thoughts that human CO₂ emissions could be a problem appeared at the end of the 19th century but were initially dismissed on the assumption that the excess would be dissolved in the ocean and not cause any trouble. It wasn't until the 1950s that scientists working on the effects of the atomic bomb tests in the Pacific realized that actually the oceans were well enough buffered that the uptake would not be that quick. This was mostly done by looking at the way different isotopes of carbon were moving around, I think, and lead directly to Charles Keeling setting up long term monitoring of CO₂ on Mauna Loa:

    http://en.wikipedia.org/wiki/Keeling_Curve

    so this was understood well enough by about 1960 or so.

    I re-read the Charney report from 1979

    http://www.atmos.ucla.edu/~brianpm/charneyreport.html

    looking for directly cited evidence but even by then it was pretty much taken for granted that the increasing CO₂ was caused by human emissions.

    I suspect that if you asked a climate scientist how we know that the atmospheric carbon dioxide increases come from human emissions it would be like asking a biologist how they know evolution happens or an astronomer how they know the Earth goes round the Sun. They'd wave their arms around and mutter something like "well, everything" - it's just not the sort of thing you can cite a recent paper as having tested but, at the same time, a huge amount of other things just wouldn't make sense without it.

    So, if the increased CO₂ is not due to human emissions then where are the human emissions going? Why do the changes in the rate of increase in atmospheric CO₂ so neatly track the increase in human emissions? Why hasn't somebody yet got the Nobel prize for showing that the radiocarbon dating of the carbon in the atmosphere is not right for the amount we're putting out?
    • CommentAuthorEd Davies
    • CommentTimeFeb 8th 2013
     
    Posted By: tony: “To attribute the whole of the rise in temperature only to greenhouse gasses is unlikely to be correct and without knowing the magnitude of this in relation to any other drivers leaves us almost guessing which of the drivers is having the most major effect.”

    Yes, attributing the whole of the rise in temperature only to greenhouse gasses would not be correct. But nobody's doing that (well, nobody serious, anyway). And yes, the magnitudes of the various drivers are not known as well as would be ideal. But, no, that doesn't just leave us guessing. This is a bit old but I think summarizes things nicely:

    http://www.realclimate.org/index.php/archives/2007/02/aerosols-the-last-frontier/

    Worth following the link on the chart for a readable version.
    • CommentAuthortony
    • CommentTimeFeb 8th 2013
     
    So all the increase in CO2 in the atmosphere are from human activity?? As the temperature of seawater rises we know that it can't hold so much dissolved CO2 so at least some of it must be a result of that. Increased levels of CO2 in the atmosphere cause plants to grow better a driving force towards reducing concentrations and incidentally leading to higher crop yields. Further cutting down trees and covering land with buildings, Tarmac and concrete all reduce the planets ability to sequester carbon indirectly leaving more in the atmosphere.

    I could step for a moment into one of your worlds where all of the increase in CO2 was anthropogenic but even there I would not be able to agree that this is entirely responsible all of the observed increase in temperatures. There are many factors that influence temperature rises other than the greenhouse effect and I am not sure that we know the relative magnitudes of these or even what they all are.

    The idea that increased CO2 levels are causing all of the observed increased temperatures still remains unproven in my book.
    •  
      CommentAuthorSteamyTea
    • CommentTimeFeb 8th 2013 edited
     
    Land use change has an affect on global temperature and is not that well understood yet, but it is not as big as the effects of increased CO2e yet, though this may change as cities get larger and affect weather patterns. Deforest/reforestation is a very tricky one as the effects are about as well understood as cloud cover. In recent years we have reversed the tree loss, but it is now in different places, less around the middle and more up north. Agriculture and wealthy northern countries are to blame for this, we have swapped some of our fields, which were forest once, for fields in developing counties that were forest very recently. This does seem to have an effect on weather pattens. There is then the variation in weather, which has been a bit strange in the last 5 years or so in the northern hemisphere, but it is still within known records, so not that strange, but we tend to notice it in the UK and drawn false conclusions.
    It is putting all the research together to make a coherent picture that is really proving a problem, but it is getting there slowly but is why I do not like the climate model forecasts and gave up studying climate change and went back to simple, measurable and testable energy use studies. I can have an idea, devise a test and measure what is really happening, box ticked regardless of hypothesis outcome, lovely.
    • CommentAuthortony
    • CommentTimeFeb 8th 2013
     
    May be I will join you
    • CommentAuthorEd Davies
    • CommentTimeFeb 8th 2013 edited
     
    Posted By: tonySo all the increase in CO2 in the atmosphere are from human activity??
    AIUI, substantially yes.

    As the temperature of seawater rises we know that it can't hold so much dissolved CO2 so at least some of it must be a result of that.
    That would be true if the partial pressure of CO₂ in the atmosphere immediately above the sea water was remaining constant. However, it's increasing so the net flow of CO₂ is into the oceans. That's why they're becoming more acidic (well, less alkaline).

    Increased levels of CO2 in the atmosphere cause plants to grow better a driving force towards reducing concentrations and incidentally leading to higher crop yields.
    Yes, some of the extra CO₂ (part of the 50 to 60% which doesn't remain in the atmosphere) goes into the land biota. (Whether it actually does much for crop yields in most cases is another matter - from what I've read it's often availability of other resources (water, trace elements, sunlight, whatever) which limits plant growth.)

    Further cutting down trees and covering land with buildings, Tarmac and concrete all reduce the planets ability to sequester carbon indirectly leaving more in the atmosphere.
    Yes, that's why I mentioned deforestation. But so what?

    I could step for a moment into one of your worlds where all of the increase in CO2 was anthropogenic but even there I would not be able to agree that this is entirely responsible all of the observed increase in temperatures.
    Did you not look at the link I gave above? People have spent a lot of time looking into this and it seems CO₂ and other human produced greenhouse gases are the main (though not quite only) cause of rising temperatures. Various other effects, anthropogenic and natural, are in play as well but most of the other effects (particular of aerosols) are tending to cause cooling, masking some of the effects of the GHGs.

    There are many factors that influence temperature rises other than the greenhouse effect and I am not sure that we know the relative magnitudes of these or even what they all are.
    Of course, we don't know what they all are and what their relative magnitudes are exactly. However, it looks like we do know the major ones and have a pretty good first approximation of their magnitudes.

    The idea that increased CO2 levels are causing all of the observed increased temperatures still remains unproven in my book.
    If you know why the increased CO₂ levels of the amount we've already got wouldn't produce warming of the about the amounts we've had I suggest you write it up and get it published 'cause you'll overturn a 100 years of research on the subject and be a very popular chap.
    • CommentAuthorEd Davies
    • CommentTimeFeb 14th 2013
     
    Posted By: tony: “As the temperature of seawater rises we know that it can't hold so much dissolved CO2 so at least some of it must be a result of that.”

    Was thinking about that in more detail (looking into Henry's law and the effect of temperature on its coefficient for CO₂ in water) when the following point rather struck me between the eyes. During the 1960s sea surface temperatures were dropping, see attached graph from the first data file referenced by http://www.metoffice.gov.uk/hadobs/hadsst3/data/download.html while CO₂ levels (http://en.wikipedia.org/wiki/Keeling_curve) were steadily rising. Even if CO₂ is coming out of the ocean (I think it isn't) it can't be much in comparison with human emissions.
    • CommentAuthortony
    • CommentTimeFeb 14th 2013
     
    Thanks for that, my understanding is that CO2 is more soluble in colder water.
    • CommentAuthortony
    • CommentTimeFeb 14th 2013
     
    May be you could try this point from the top of the page as you are on a roll

    "I have said that I cannot see how any model that has regard to this equation (Stefans Law) can predict exponential or even increasingly rapid temperature rises (the typical hockey stick graphs we have all seen). It is for this reason alone that I am unhappy with the models that show these types of increases. " quoting myself from the top of the page
    • CommentAuthormike7
    • CommentTimeFeb 14th 2013
     
    Ed has been doing such sterling work I doubt I could make any contribution, but just possibly this might help:-
    Tony, I think you have it back to front. The hockeystick rise is most dramatic in the level of CO2 in the atmosphere since the industrial revolution - about a 50% increase. The temperatures involved in the S-B law are absolute, ie in degrees Kelvin, and we are looking at a rise of a few degrees - one or two percent of absolute - as being earth-changing and possibly catastrophic. It may still look like a hockey stick if you loose sight of the bottom of the graph, but otherwise it's a teeny uptick, but by all accounts a very significant one.

    If the earth's temperature were only determined by the CO2 level and the S-B law, the power factor of 4 would, to my simple mind at least, suggest that a 50% rise in CO2 would result in a 12.5% rise in temperature. 12.5% of 290deg K is about 36 deg!
    • CommentAuthorseanie
    • CommentTimeFeb 14th 2013
     
    The "typical hockey stick graphs we have all seen" have nothing at all to do with predictions of temperature rises. Most are simply already observed temperature records overlaid onto pre-instrumental temperature reconstructions. Paleoclimatology and climate modelling are different things.
    •  
      CommentAuthorSteamyTea
    • CommentTimeFeb 14th 2013
     
    Bit on the radio at the moment about it:
    http://www.bbc.co.uk/podcasts/series/iot

    And lots in this weeks comic:
    http://www.newscientist.com/issue/current
    • CommentAuthorEd Davies
    • CommentTimeFeb 14th 2013 edited
     
    Posted By: tonyI have said that I cannot see how any model that has regard to this equation (Stefans Law) can predict exponential or even increasingly rapid temperature rises (the typical hockey stick graphs we have all seen).

    To be honest, I'd hoped I'd already knocked the relevance of Stefan's Law on the head.

    Still, this is a bit of a strawman argument - nobody's predicting "exponential" temperature rises, just a rise of quite a few degrees over the next century or so. That looks steep compared with the last few thousand years of global temperatures, that's the point of the Hockey Stick, but it's still proportionally a small change. A six degree rise would be pretty disastrous but, as mike7 points out, it'd only be a 2% increase in the 300 K or so in the average surface temperature.

    It's worth remembering that the world has warmed by 6 K or a bit more since the Last Glacial Maximum as a result of the fairly weak Milankovitch cycles. Neither Stefan nor Boltzmann managed to stop that.

    http://en.wikipedia.org/wiki/File:Vostok_Petit_data.svg
    • CommentAuthorEd Davies
    • CommentTimeFeb 14th 2013
     
    Posted By: tonyThanks for that, my understanding is that CO2 is more soluble in colder water.

    Yes. I found this paper a day or two ago but when I looked more closely this afternoon it seems to be about solubility of CO₂ in water when the gas above the surface is at pressures of a few atmospheres, not the much smaller partial pressure in the natural atmosphere.

    http://www.nist.gov/data/PDFfiles/jpcrd427.pdf

    My understanding is that the relatively small rise is sea surface temperatures (which are lagging (and holding back) land temperatures due to the thermal inertia of the sea) reduce the amount of CO₂ the oceans can hold by much less than the amount of extra that's going into the atmosphere. Still, it would be nice to know the exact numbers so I plan to look into this further.
    • CommentAuthorEd Davies
    • CommentTimeMar 3rd 2013
     
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