Cause and Effect and Global Warming

Discussion in 'Environment' started by JohnStOnge, Jan 24, 2009.

  1. JohnStOnge
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    JohnStOnge Member

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    I think that many people believe that a cause and effect relationship between human activity and elevations in global temperatures over time has been unequivocally demonstrated. That is not true. Inferring a cause and effect relationship on the basis of statistical data requires controlled experimentation and, of course, controlled experimentation to infer a cause and effect relationship in the referenced case is not possible. It should be noted that the IPCC concedes that point in its 2007 Working Group 1 Report, The Physical Science Basis of Climate Change.

    I'd post a link to the report but I don't have 15 posts yet and this site doesn't allow posting links until a person gets to that point. But you can find it at the IPCC web site. So find it, pull up the pdf version of Chapter 9, Understanding and Attributing Climate Change,, then go to page 660 (the sixth page of that chapter). Or you can pull up the web page version and do a search for the word "experiment." In the pdf version, you'll find the relevant language starting at the bottom of the page in the left column. It goes like this:

    "‘Attribution’ of causes of climate change is the process of establishing the most likely causes for the detected change with some defined level of confidence (see Glossary). As noted in the SAR (IPCC, 1996) and the TAR (IPCC, 2001), unequivocal attribution would require controlled experimentation with the climate system. Since that is not possible..."

    After the word "possible" the authors go on to explain what they did given the situation. But that is not important to the point. The situation is that unequivocal "attribution" is not possible. Otherwise, I don't agree with their use of the terminology "level of confidence." The concept of a confidence level with respect to inferring cause and effect is intimately tied to the concept of a controlled experiment. You can't really have a credible confidence level with respect to cause and effect without the experimental control, and I think the IPCC is misleading the public in representing probability statements it makes as confidence levels. I think it gives the statements an aura of quantitative credibility that is not really justified.

    There are other references in the report to controlled experimentation being needed to infer cause and effect, but the one I quoted is the most direct and unambiguous instance of conceding the principle that I could find.

    Finally, note that there are a lot of references to "experiments" in the report that are not experiments on anything real. They are experiments on models. They tell the investigators what doing different things will make the models say. They're great for infering cause and effect with respect to what the models do. But they can't be viewed as legitimately inferring cause and effect with respect to the actual climate system.
     
  2. Old Rocks
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    Old Rocks Diamond Member

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    Relevant experiments were done over a hundred years ago, and defined how CO2 absorbed various wavelengths of infrared. Predictions were made that increasing the GHGs in the Earth's atmosphere would result in the warming of the Earth. That is exactly what has happened.

    We have increased the level of CO2 in the atmosphere by 40%, and the CH4 by 250%. We have leveled forests, and decreased the ability of the natural world to absorb the excess CO2 we have generated by the burning of fossil fuels.

    We are now seeing the results of the increased CO2 and other GHGs in the melting of glaciers and ice caps.We are observing an acidification of the ocean waters, getting very close to an amount that will negatively affect the single celled plants and animals at the base of the food chain.

    You can parse the meaning of the words all you care to. That does not change the reality of the effects of our changing the amount of GHGs in the atmosphere.
     
  3. dilloduck
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    dilloduck Diamond Member

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    Who cares ?
     
  4. Old Rocks
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    Old Rocks Diamond Member

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    Most people with a little intelligence.
     
  5. JohnStOnge
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    JohnStOnge Member

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    It's not a matter of parsing words. The fact that predictions of a general warming trend were made and a general warming trend was observed does not mean cause and effect was inferred. It means an association consistent with the the expectation was observed. But association in observational data does not prove causation. To infer cause and effect, you need to make a prediction then conduct a controlled experiment that yields results consistent with it. If you want I can post a discussion of that principle from a statistics text.

    But I really don't think that's necessary. First of all, I suspect you already know I'm right about the rule. If not, the IPCC itself concedes the point. For several year's I told people that cause and effect had not been inferred but I'd never actually looked at the IPCC text. Finally I decided to look and found that they do recognize the principle. They don't spend a lot of time on it. They kind of sweep it under the rug. But they recognize it and note that what it would take to provide an unequivocal cause and effect inference is not possible. There's no need to parse words with respect to the language I quoted. The authors pretty directly said that unequivocal attribution would require controlled experiments that are not possible.
     
    Last edited: Jan 25, 2009
  6. Old Rocks
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    Well, it is not very well controled, but we are making the experiment. I do not see the CO2 rise stopping before 500 ppm or more. If we are not already over the tipping point, we will be at some point before we reach the 500 ppm level. At some point after the tipping point there will be an adrupt climate change that will change the aspect of survival for all things living on this planet. Definately the planet will no longer support the present human population.

    We have seen this progression in geological history. Feedback from PETM could explain sustained warming
    © 2004 Eugene S. Takle
    Feedback from PETM could explain sustained warming



    An abrupt global warming 55 million years ago, often referred to as the Palaeocene/Eocene thermal maximum (PETM), occurred in connection with a massive release of 1,000-2,000 Gt of carbon in the form of methane hydrate from the ocean floor (Bowen et al., 2004). Although long-lived by human-lifetime standards, carbon dioxide (lifetime ~ 100 years) and methane (lifetime ~ 10 years) have short lifetimes by geological standards. So the reason for the sustained warming of the PETM remains a mystery. Increases in tropospheric water vapor and decreased soil sequestration of carbon, both of which will occur quickly with the stratospheric build up of carbon dioxide and methane, likely contributed as positive feedbacks to the warming. On the other hand, delayed negative feedbacks, such as weathering of silicates and delivery of nutrients and alkalinity to oceans would have contributed negative feedbacks that gradually (over 70,000 years) allowed the climate to recover from the 5 to 10 degree Celsius warming.

    The noteworthy message of Bowen et al. (2004) is that not all feedbacks have the same time scale and that the carbon-induced warming of the PETM likely triggered some kind of positive feedback that amplified and sustained the abrupt rise in temperatures. The negative feedback, although possibly equally as effective, was slower to become established and lasted well beyond the effective period of the positive feedback. Will there be an analogous and abrupt positive feedback to amplify the current warming?


    Reference
    Bowen, G.J., D.J. Beerling, P.L. Koch, J.C. Zachos, and T. Quanttlebaum, 2004: A humid climate state during the Palaeocene/Eocene thermal maximum. Nature, 432, 495-499.
     
  7. Old Rocks
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    Past global warming suggests massive temperature shift in our future
    mongabay.com
    December 7, 2006


    If past climate change is any indication, Earth could be in store for some significant global warming according to research published in the December 8, 2006, issue of the journal Science. The work suggests that climate change skeptics may be fighting a losing cause.




    The study, led by Mark Pagani, associate professor of geology and geophysics at Yale, looked at an episode of rapid climate change that occurred some 55 million years ago. Known as the Paleocene-Eocene Thermal Maximum (PETM), the period was marked by a rapid rise in greenhouse gases that heated Earth by roughly 9° F (5° C), in less than 10,000 years. The climate warming caused widespread changes including mass extinction in the world's oceans due to acidification and shifts of plant communities due to changes in rainfall. The era helped set the stage for the "Age of Mammals," which included the first appearance of modern primates.

    The research, based on fossil records of terrestrial plants and oceanic plankton, suggests that the world's climate is highly sensitive to atmospheric carbon dioxide (CO2) levels, finding that a doubling of CO2 concentrations can raise global temperatures by at least 4 ºF (2.2 ºC). Current projections show that natural background atmospheric carbon dioxide levels are expected to double around mid-century due to fossil fuel combustion.

    Past global warming suggests massive temperature shift in our future
     
  8. elvis
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    elvis BANNED Supporting Member

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    And the scientists that hold the view that global warming was NOT caused by man have no intelligence?
     
  9. Old Rocks
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    Dr Guy Harrington's Research Pages
    Terrestrial environmental changes during the PETM

    The Palaeocene–Eocene Thermal Maximum (PETM) is a rapid global warming event at ≈ 55.8 Ma that had major impacts upon terrestrial and marine biota. The PETM was probably caused by the massive release of greenhouse gases at similar rates to present and forecast rates of fossil fuel burning. This pulse of global warming entailed c. 8 ºC warming of sea-surface temperatures at high latitudes and an increase of land temperatures by c. 4–6 ºC in warm-temperate, continental North America. This event is well documented from several terrestrial settings but there are very few floral records from within the PETM.


    Part of this research is in collaboration with Dr Scott Wing (Smithsonian Institution), Dr Jon Bloch (University of Florida), Dr Francesca Smith (Northwestern), and Doug Boyer (Stony Brook) and investigated remote parts of the Bighorn Basin which yielded fossil mammals, plants and pollen. Early results indicate that massive change occurred to plant communities leading to rapid taxonomic turnover. Plants with contemporaneous tropical distribution are found fleetingly in the Bighorn Basin together with immigrant taxa that mark the Early Eocene in warmer parts of North America, such as the US Gulf Coast. When temperatures cooled after this event, plants that thrived in the Palaeocene of the Bighorn Basin return (there is no extinction) and are joined by a few immigrant taxa that previously were found only on other Holarctic continents. The plant response to this warming varies by region because extinction of ≈20% is noted from the eastern US Gulf Coast.


    I have studied other parts of North America including the Palaeocene–Eocene transition on the eastern US Gulf Coast (Mississippi and Alabama) and from North Dakota. Palynological, sedimentological and geochemical changes from North Dakota are being studied with Dr Clay Kelly and Dr Cynthia Stiles (University of Wisconsin, Madison) in order to understand the role of silicate weathering within the PETM. The PETM is present within the Golden Valley Formation which weathers as prominent brightly coloured buttes in west-central North Dakota (see below).

    Dr Guy Harrington's Research Pages
     
  10. garyd
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    garyd Senior Member

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    In a word nonsense. CO2 has already given us 75% of the warming we can expect from CO2 alone.
     

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