How Accurate are Global Temperatures?

Discussion in 'Environment' started by IanC, Sep 24, 2010.

  1. IanC
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    IanC Gold Member

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    First off- global temps are difficult to measure, adding up readings from different areas of the land and sea is a complex job.

    Second- it doesn't matter that much what the number actually is (accuracy) as long as we can measure how much it is changing (precision).

    My problem with totally believing the figures that we are getting about global warming is the adjustments that are being made to the measurements. These adjustments are made for many reasons, such as changing from one type of instrument to another or filling in missing areas. But they almost always step up. By step up I mean that the accuracy figure (actual temperature) is raised step and then precision measurements are based on that new increased baseline. But the new higher baseline is compared to older lower baselines.

    Why does this matter and how are biases introduced? Take satellites, when one generation is replaced by the next there is an overlap and they try to calibrate them together but often the first satellite is badly degraded. The people who manage the satellites often disagree with the adjustments made to their instruments' readings but they can't really do anything about it. And the baseline always goes up. The diving buoys for measuring ocean temps originally produced data that showed substantial cooling for the early 00's. They were checked, scrutinized and recalibrated until the readings were more in line. Would this have happened if the data had shown higher temps? The surface station readings have been a total travesty. Poor placement, massive loss of individual stations, poor data collection methodologies and of course temperature adjustments that often are the majority of the trend.

    I am not saying there has been no temperature increase. But I am saying that biased adjustments in just about every area have had a significant effect on the overall trend of increasing temps.
     
  2. konradv
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    konradv Gold Member

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    That's why GHGs concentrations are so important. Given their ability to absorb infra-red radiation and their 25-30% increase over historical averages since the advent of the Industrial Revolution, logic tells us that warming is inevitable, if the trend continues.
     
  3. edthecynic
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    edthecynic Censored for Cynicism

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    That's why ANOMALIES are used to measure the TREND!!!

    And the buoys were found to have faulty depth gauges. They were deeper than their gauges recorded giving colder temps. Of course, deniers want faulty data if it supports their global cooling hoax and call eliminating faulty data a conspiracy. :cuckoo:

    [​IMG]
     
  4. IanC
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    IanC Gold Member

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    Ed- you are making my point for me. Those buoys would not have got the same scrutiny if they were reading higher instead. Why isn't the same effort put into other areas? No one gives a shit if a land temp station is on an airport tarmac or under an airconditioning vent. No one (in climate science peer review) gives a shit if statistical methods are wrong or the data is used upside down, as long as the results are pleasing to them. And there is always the easy fix of making 'adjustments' to the raw data, because until lately skeptics were powerless to get their questions answered.
     
  5. edthecynic
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    edthecynic Censored for Cynicism

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    PURE BULLSHIT!!!!!

    Again, that is why ANOMALIES are used to show the trend and not the direct temperature reading like you deniers mislead the gullible with.

    If a temp station is near a heat source, the 30 year average the anomaly is measured against for that station will be higher so the TREND will be accurate.
    You know it, I know it and your dishonest sources know it.
     
  6. IanC
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    IanC Gold Member

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    I have already posted quite a few examples of both urban heat effects and bizarre 'corrections' that should give any thinking person more than enough information to question whether the trend is even upward in many cases, and whether the size of the trend is from data readings or from the large manipulations the raw data go through before being presented to the public. Do you know that NASA GISS made an error at year 2000? And when it was found by a skeptic, NASA went back and changed all the pre-2000 figures instead of correcting the few post-2000 years. Why?
     
  7. Old Rocks
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    Old Rocks Diamond Member

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    OK. So you want a gauge that will not reflect 'heat island affect' of modern cities. There is one that is readily available. They are called glaciers. And the majority, worldwide, are in an accelerating retreat.

    http://www.igsd.org/documents/TibetanPlateauGlaciersNote_10August2010.pdf


    Summary
    According to the IPCC, the global average surface temperature increase from 1850-1899 to 2001-2005 is 0.76°C ± 0.19°C. V. Ramanathan and Y. Feng from the Scripps Institution of Oceanography, University of California, San Diego, calculate that greenhouse gas emissions as of 2005 have committed the planet to warming of “2.4ºC (1.4º-4.3º) above the preindustrial surface temperatures.” The Tibetan Plateau is warming about three times the global average. Since the 1950’s, warming in excess of 1ºC on the Tibetan side of the Himalayas has contributed to retreat of more than 80% of the glaciers. Melting glaciers endangers the fresh water supply and food security of billions of people in Asia. The warming also contributes to the land use changes, especially melting of permafrost, which could result in significant carbon loss. Black carbon (soot) may have a significant effect on melting snow and glaciers equaling the impact of increased atmospheric CO2. Therefore, in addition to a central reduction of CO2, it is imperative to implement fast-action strategies to reduce non-CO2 warming agents, including black carbon, hydrofluorocarbons, methane and tropospheric ozone precursors, as well as expand bio-sequestration and enhance urban albedo which together can reduce committed warming and associated abrupt climate changes on a decadal timescale.
     
  8. Old Rocks
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    Old Rocks Diamond Member

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    An overview of glacier trends

    Both approaches show consistent results (with all glaciers showing a slightly faster drop in mass compared to the 30 reference glaciers). There is strong mass loss in the first decade from 1945. Note that at this time, there were only several glaciers monitored - not quite a global sample. The mass loss slows down in the second decade so that around 1970, global mass balance was close to zero. Glaciers were in near equilbrium which indicates glacier shrinkage in the late 20th Century is essentially a response to post-1970 global warming (Greene 2005).

    After 1975, glacier shrinkage continues to accelerate until present. The mass loss from 1996 to 2005 is more than double the mass loss rate in the previous decade of 1986 to 1995 and over four times the mass loss rate over 1976 to 1985. When you narrowly focus on a few cherry picked glaciers, you can be misled into an incorrect view of global glacier trends. When you take in the broader picture, you see that globally, glaciers are shrinking at an accelerating rate.
     
  9. Old Rocks
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    Old Rocks Diamond Member

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    JSTOR: An Error Occurred Setting Your User Cookie

    Abstract
    Worldwide glacier mass changes are considered to represent natural key variables within global climate-related monitoring programmes, especially with respect to strategies concerning early detection of enhanced greenhouse effects on climate. This is due to the fact that glacier mass changes provide important quantitative information on rates of change, acceleration tendencies and pre-industrial variability relating to energy exchange at the earth/athmosphere interface. During the coming decades, excess radiation income and sensible heat (a few watts per square metre) as calculated with numerical climate models are both estimated to increase by a factor of about two to four as compared to the mean of the 20th century. The rate of average annual mass loss (a few decimetres per year) measured today on mountain glaciers in various parts of the world now appears to accelerate accordingly, even though detailed interpretation of the complex processes involved remains difficult. Within the framework of secular glacier retreat and Holocene glacier fluctuations, similar rates of change and acceleration must have taken place before, i.e. during times of weak anthropogenic forcing. However, the anthropogenic influences on the atmosphere could now and for the first time represent a major contributing factor to the observed glacier shrinkage at a global scale. Problems with such assessments mainly concern aspects of statistical averaging, regional climate variability, strong differences in glacier sensitivity and relations between mass balance and cumulative glacier length change over decadal to secular time scales. Considerable progress has recently been achieved in these fields of research.
     
  10. Old Rocks
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    Old Rocks Diamond Member

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    I can post a lot more studies from real scientists concerning the accelerating loss of glacial ice worldwide.
     

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