Average global temperature

Discussion in 'Earth Science' started by vhawk, Mar 2, 2009.

  1. D H Some other guy Valued Senior Member

    Scientists are precise -- in the scientific literature. When writing for the lay person, those nuances in the scientific literature go right over most people's heads -- and take up too much print space that is better allocated to an ad for the newest pair of running shoes.
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  3. Trippy ALEA IACTA EST Staff Member

    You're quoting someone else and attributing it to me? Nice debating tactic there bud.
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  5. Trippy ALEA IACTA EST Staff Member

    Most statements relating to global average temperature also relate back to a graph. That graph should give you all the information you need to qualify the statement "The average global temperature is increasing".

    And no, a dynamic systemm can also have an average temperature, however usually it's a running average. A running average is simply the average of the "X points of data up to and including the most recent data point".
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  7. iceaura Valued Senior Member

    And it was buffalo, too, in a state of confusion. Hard to apologize enough for that. But it's fixed.
  8. Trippy ALEA IACTA EST Staff Member

    Syzygys said over here:http://www.sciforums.com/showthread.php?p=2246497
    In response to me saying:
    But IQ is irrelevant to the discussion, and does not represent the only statististical measure of people.
    Unless you're going to try and argue that everybody is the same height and weight (measures that are also disparate).
  9. Syzygys As a mother, I am telling you Valued Senior Member

    It sound easy first, but if you think about it, there still need further definition. For example, at what time are we measuring? When it is noon is the USA or when it is 2 am? Since land warms up faster than water, measuring it when a large landmass has the afternoon should give a higher temperature, when it happens over the ocean.

    The point is that the temperature is constantly changing, thus averaging it might not be possible.

    In a separate thread someone brought up humans as analogy, that we can average them. It is actually a good analogy, because it shows that averaging can not always be done or be comparable.

    Let's look at IQ. What is the average IQ of humans? Most would say 100. But can we really compare a homeschooled Amish kid with a private student in Japan???

    So what time would you do the Earth average measure according to EST, and why exactly then?
  10. Trippy ALEA IACTA EST Staff Member

    It's already been explained to you that the comparison to IQ is at best fallicous.
  11. Syzygys As a mother, I am telling you Valued Senior Member

    Kind of funny, because you actually said the OPPOSITE of it in another thread.

    Now to be truthful, first I stated it was a bad analogy, but after thinking about it, I actually find it correct. Just like you can not average human population all the time (in case of IQ for example) we might can not average global temperature....
  12. Syzygys As a mother, I am telling you Valued Senior Member

    Anyhow, let's jumpstart this thread again with the following and note, I don't care about global warming and political bullshits:

    1. If there is an average global temperature, what is it and how is it measured?

    2. How does it change/fluctuate during the day and during the year?

    3. For measuring localities are we using an evenly spread grid or just important points (big cities)? If the later, is that the correct way?

    4. If we are using different (more) localities than in the past, how do we know just how accurate is our comparison to the past???
    Last edited: May 7, 2009
  13. Syzygys As a mother, I am telling you Valued Senior Member

    After googling the question I found a blog, and I came to the same conclusion as this:

    "Simply put, if you have a large flat area with sensors evenly spaced, it is obvious how to derive an average value. But what if the area is very large, sensors are not at all evenly spaced, vast areas (oceans) have no surface sensors, sensors are at different elevations, placed in totally different surroundings, and may not even be completely consistent as to instrumentation and method, how do you derive a single number that represents the global average temperature? And, is this a meaningful number? (A good example of a meaningless average is the one you get by finding the mean of all the telephone numbers in your town. It’s correct, but what is it..?)

    I’m also wondering, since there are so many ways to take a global average, to weight the various local values according to the area they represent, does everyone do it the same way? Does it make a difference how they do it?

    Well, I am not alone in asking this fundamental, I think, question. Better mathematical minds than mine have examined it, and I came across this fascinating paper, Does a Global Temperature Exist? The extended introduction is quite accessible to non-mathematicians, and does an excellent job of explaining the crux of the issue. I quote the rather brief conclusion to the paper in full below, with my emphasis:

    There is no global temperature. The reasons lie in the properties of the equation of state governing local thermodynamic equilibrium, and the implications cannot be avoided by substituting statistics for physics.

    Since temperature is an intensive variable, the total temperature is meaningless in terms of the system being measured, and hence any one simple average has no necessary meaning. Neither does temperature have a constant proportional relationship with energy or other extensive thermodynamic properties.

    Averages of the Earth’s temperature field are thus devoid of a physical context which would indicate how they are to be interpreted, or what meaning can be attached to changes in their levels, up or down. Statistics cannot stand in as a replacement for the missing physics because data alone are context-free. Assuming a context only leads to paradoxes such as simultaneous warming and cooling in the same system based on arbitrary choice in some free parameter. Considering even a restrictive class of admissible coordinate transformations yields families of averaging rules that likewise generate opposite trends in the same data, and by implication indicating contradictory rankings of years in terms of warmth.

    The physics provides no guidance as to which interpretation of the data is warranted. Since arbitrary indexes are being used to measure a physically non-existent quantity, it is not surprising that different formulae yield different results with no apparent way to select among them.

    The purpose of this paper was to explain the fundamental meaninglessness of so-called global temperature data. The problem can be (and has been) happily ignored in the name of the empirical study of climate. But nature is not obliged to respect our statistical conventions and conceptual shortcuts. Debates over the levels and trends in so-called global temperatures will continue interminably, as will disputes over the significance of these things for the human experience of climate, until some physical basis is established for the meaningful measurement of climate variables, if indeed that is even possible.

    It may happen that one particular average will one day prove to stand out with some special physical significance. However, that is not so today. The burden rests with those who calculate these statistics to prove their logic and value in terms of the governing dynamical equations, let alone the wider, less technical, contexts in which they are commonly encountered."

  14. Trippy ALEA IACTA EST Staff Member

    I stated that Human Beings had statistically disparate measures that it was useful to talk about averages of, and then clarified in this thread that I was never refering to IQ.
    That I was ever refering to IQ is completely imagined by you.

    This is just total and utter BS, it's not the value of talking about an average IQ that has ever been in question, it's the value of the concept of IQ itself, and the wording of the questions.
    You (wrongly) assumed that IQ has something to do with education, and drew the fallicous example of comparing an Amish Kid with a Japanese kid. IQ is about potential smarts, problem solving ability, and pattern recognition, NOT general knowledge.
    The potential problem with IQ is that if you compare the average IQ in america, with the average IQ of Japan, and find a significant difference, does that significant difference represent a real disparity, is it just a reflection of slightly different testing methods, or is it a reflection of the difference of white americans to answer a test written by white americans for white americans versus the ability of Japanese to answer a test written for white americans by white americans.

    Talking about the average temperature of the earth is completely different, and is actually useful.
  15. Trippy ALEA IACTA EST Staff Member

    This, is bullshit.
    The author of this blog doesn't know what he's talking about.
    He's completely lost track of the fact that Temperature itself is a statistical measurement.
    It's a measurement of the average amount of kinetic energy contained by the particles that make up a solid.
  16. Trippy ALEA IACTA EST Staff Member

    Think of talking about the average temperature of the earth this way.
    Take this map of the annual mean temperature.

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    Take a globe or sheet of material, and heat/cool to create a scaled map of it.
    Insulate perfectly your globe or sheet.
    Allow it to come to thermal equilibrium with itself, but not loose any heat energy to its surroundings.
    Measure the temperature of your globe or sheet, and you have DIRECTLY measured the mean annual temperature of the earth.
  17. Syzygys As a mother, I am telling you Valued Senior Member

    so let's repeat, because I didn't get answers to any of these:

  18. Trippy ALEA IACTA EST Staff Member

    1. It's the mean global temperature.
    It's measured by calculating an average based on daily readings (or in some cases, continuous readings.

    2. It doesn't.
    The average temperature for January is always that.
    The average temperature in September may be different, but the average annual temperature takes this into account.

    3. There is no fixed pattern to measuring localities, measurements are generally taken where there are people, however satellites are capable of measuring it over the entire surface at the same time each day. Is there a right way or a wrong way? Who knows. The denser the points, the more accurate the data (just like surveying), part of the problem is convincing those in charge of the purse strings to spend money putting weather stations in the middle of nowhere (because they have to be maintained as well as established.
    It was once proposed to divide the earth into a chequer grid, and have a station at the center of each square, alternately measuring temperature and humidity, the general idea being, the mor epoints you have, the more accurate the discussion.

    4. Because there are some localities that are 'representative' of the average environment, and there are other localities where we can directly compare current and historical measurements or proxie, and there are some proxies that depend on the average environment, rather than the local environment (because they're not sensitive to short term fluctaions such as seasonal and diurnal variations).
  19. iceaura Valued Senior Member

    Most things that are normally and routinely averaged - such as sound volume, speed, inflation rates, humidity, sea level, etc, - are constantly changing. That's why they're averaged, rather than simply measured.

    Your ear averages, separately, both the rate and the size of very complex and ever changing pressure fluctuations impinging upon the eardrum, and hands you a pitch and a volume automatically. It then averages those changing averages, and hands you a timbre. This business of averaging things is complex, but routine. Your very perception of temperature on your skin is based on averaging the changing differences between two averages of the changing temperatures at the surface and a little way in. You probably find various overall global or partial averages useful - whether your hands and face are generally colder than the rest of you, for example. Global temperature is averaged over some useful period of time and space - a year over a major ecological region is one of the standard intervals that has come in handy - in more or less similar fashion.
  20. Syzygys As a mother, I am telling you Valued Senior Member

    But what is it?

    So there is fluctuation in Sept but not in January? And how much is it? Looks like the global average is pretty much standard and if fluctuates it does very little, probably 1-2 F.

    And that's where the historical accuracy comes in. let's say the Western Hemisphere where cities are plenty did measure an increase in the averages, but what is Siberia has a decrease at the same time? We will just never know, because Siberia hasn't been very well populated.

    Now I understand we can take a heatmap of the world, but since we don't have those going back for 100 years, comparing it is impossible. And itself the map doesn't say much unless we can see fluctuations on it....
  21. Syzygys As a mother, I am telling you Valued Senior Member

    Scientic treatment of the topic:


    Does a Global Average exist?

    I am presenting this instead of dealing with Trippy's BS comments. I can't argue with no argumnets...

    Just an analogy about averages not always being meaningful:

    Let's say after averaging humans' legs we arrive at the conclusion that humans have 1.98 legs. Is this number meaningful? It simply says that some people lost 1 or both legs, but the exact number is really irrelevant, because we can not make 1.98 shoes instead of a pair and such.
  22. iceaura Valued Senior Member

    I posted a bunch of examples showing that averages are not always meaningless.
    A good rule of thumb is that anything on the internet pertaining to the effects of the recent anthropogenic CO2 boost that has Ross McKitrick's name attached to it is spam.

    The paper you linked is a work of philosophy, in which a slippery notion of "physically meaningful" is employed to cover up the lack of relevance of any of its mathematics to the physical situation of interest, which is lower atmosphere and surface water temperature as it affects human beings.

    Of lower atmospheric air and surface water temperature for a given length of time over a defined area of the globe, of course. It's physical stuff, all of it has a temperature all the time, and it has therefore an average temperature over a given length of that time.
  23. Trippy ALEA IACTA EST Staff Member

    As I have already explained to you, the average annual temperature of the globe is, effectively the temperature the earth would reach if its surface temperature was allowed to reach equilibrium, without loosing heat energy into space.

    No, this isn't what I said at all.
    If you're going to argue, at least try and be accurate about what I've said, I have very little tolerance for liars, whether they do so deliberately or inadvertantly.
    What I said was that the average temperature in January is the average temperature in January, it doesn't vary much from year to year (excluding global warming or any other such considerations for the time being).
    BUT the average temperature in September might be different from the average temperature in January, however the average temperature in September doesn't vary much from year to year either (excluding the same considerations).
    Here's a graph that illustrates what I'm talking about.

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    Here's another example that gives us a spatial distribution as well.

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    And that's where Proxies and Satellites come into it.
    And if one increases more than the other decreases, then the average will increase.

    Short term, and local variations are irrelevant when considering averages, especially if you use the right proxies.
    More to the point, we can reconstruct the history of temperature through various proxies - there are, after all, things that are sensitive to local, and short term variations that leave a permanent record which can be deconvoluted to give an accurate, historical record of the temperature in that area, even though there might not have been people there to measure it.

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