carbon 14 and agw

Discussion in 'Environment' started by Old Rocks, Jan 31, 2012.

  1. Old Rocks
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    Old Rocks Diamond Member

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    Hemispheric shift in atmospheric radiocarbon
    Observations of radiocarbon in CO2 at seven global sampling sites in the Scripps flask network: Analysis of spatial gradients and seasonal cycles – Graven et al. (2012)


    Abstract: “High precision measurements of Δ14C were conducted for monthly samples of CO2 from seven global stations over 2- to 16-year periods ending in 2007. Mean Δ14C over 2005–07 in the Northern Hemisphere was 5 ‰ lower than Δ14C in the Southern Hemisphere, similar to recent observations from I. Levin. This is a significant shift from 1988–89 when Δ14C in the Northern Hemisphere was slightly higher than the South. The influence of fossil fuel CO2 emission and transport was simulated for each of the observation sites by the TM3 atmospheric transport model and compared to other models that participated in the Transcom 3 Experiment. The simulated interhemispheric gradient caused by fossil fuel CO2 emissions was nearly the same in both 1988–89 and 2005–07, due to compensating effects from rising emissions and decreasing sensitivity of Δ14C to fossil fuel CO2. The observed 5 ‰ shift must therefore have been caused by non-fossil influences, most likely due to changes in the air-sea 14C flux in the Southern Ocean. Seasonal cycles with higher Δ14C in summer or fall were evident at most stations, with largest amplitudes observed at Point Barrow (71°N) and La Jolla (32°N). Fossil fuel emissions do not account for the seasonal cycles of Δ14C in either hemisphere, indicating strong contributions from non-fossil influences, most likely from stratosphere-troposphere exchange.”

    Citation: Graven, H. D., T. P. Guilderson, and R. F. Keeling (2012), Observations of radiocarbon in CO2 at seven global sampling sites in the Scripps flask network: Analysis of spatial gradients and seasonal cycles, J. Geophys. Res., 117, D02303, doi:10.1029/2011JD016535.
     
  2. Old Rocks
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    Old Rocks Diamond Member

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    Fossil fuel emissions are the strongest contributor to atmospheric radiocarbon trends
    Observations of radiocarbon in CO2 at La Jolla, California, USA 1992–2007: Analysis of the long-term trend – Graven et al. (2012)

    Abstract: “High precision measurements of Δ14C were performed on CO2 sampled at La Jolla, California, USA over 1992–2007. A decreasing trend in Δ14C was observed, which averaged −5.5 ‰ yr−1 yet showed significant interannual variability. Contributions to the trend in global tropospheric Δ14C by exchanges with the ocean, terrestrial biosphere and stratosphere, by natural and anthropogenic 14C production and by 14C-free fossil fuel CO2 emissions were estimated using simple models. Dilution by fossil fuel emissions made the strongest contribution to the Δ14C trend while oceanic 14C uptake showed the most significant change between 1992 and 2007, weakening by 70%. Relatively steady positive influences from the stratosphere, terrestrial biosphere and 14C production moderated the decreasing trend. The most prominent excursion from the average trend occurred when Δ14C decreased rapidly in 2000. The rapid decline in Δ14C was concurrent with a rapid decline in atmospheric O2, suggesting a possible cause may be the anomalous ventilation of deep 14C-poor water in the North Pacific Ocean. We additionally find the presence of a 28-month period of oscillation in the Δ14C record at La Jolla.”

    Citation: Graven, H. D., T. P. Guilderson, and R. F. Keeling (2012), Observations of radiocarbon in CO2 at La Jolla, California, USA 1992–2007: Analysis of the long-term trend, J. Geophys. Res., 117, D02302, doi:10.1029/2011JD016533.
     
  3. CrusaderFrank
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    CrusaderFrank Diamond Member

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    So its not due to AGW, thank you
     
  4. Old Rocks
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    Old Rocks Diamond Member

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    LOL. Frankyboy, you haven't the slightest idea of what is being discussed. LOL
     
  5. CrusaderFrank
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    CrusaderFrank Diamond Member

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    The observed 5 ‰ shift must therefore have been caused by non-fossil influences

    Do you read stuff before you post it?
     
  6. Old Rocks
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    Old Rocks Diamond Member

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    You dumb fuck, they are discussing the source of the 5% differance in delta C14 from one hemisphere to the other. Perhaps you should go to the source and look at the graph in the article.
     
  7. CrusaderFrank
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    CrusaderFrank Diamond Member

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    Look out, squirrels are getting bigger!

    I went to the site and found this too
     
  8. CrusaderFrank
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    CrusaderFrank Diamond Member

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    yes, it said "non-fossil influences" there too
     
  9. Old Rocks
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    Old Rocks Diamond Member

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    AGW Observer

    Look out, squirrels are getting bigger!
    Size Increase in High Elevation Ground Squirrels over the Last Century – Eastman et al. (2012)

    Abstract: “There is increasing evidence for morphological change in response to 20th century environmental change, but how this relates to fluctuations in geographic range is unclear. We measured museum specimens from two time periods (1902-1950 and 2000-2008) that vary significantly in climate to assess if and how two high elevation contracting species of ground squirrels in the Sierra Nevada of California, Belding’s ground squirrel (Urocitellus beldingi) and the golden-mantled ground squirrel (Callospermophilus lateralis), and one lower elevation, stable species, the California ground squirrel (Otospermophilus beecheyi), have responded morphologically to changes in California over the last century. We measured skull length (condylobasal length), an ontogenetically more labile trait, and maxillary toothrow length (MTRL), a more developmentally constrained trait. C. lateralis and U. beldingi, both obligate hibernators, have increased in body size but have not changed in body shape. In contrast, O. beecheyi, which only hibernates in parts of its range, has shown no significant change in either morphometric trait. The increase in body size in the higher elevation species, presumably a plastic effect due to a longer growing season and thus prolonged food availability, opposes the expected direction of selection for decreased body size under chronic warming. We hypothesize that population contraction is related to physiological rather than nutritional constraints.”

    Citation: Lindsey M. Eastman, Toni Lyn Morelli, Kevin C. Rowe, Chris J. Conroy, Craig Moritz, Global Change Biology, DOI: 10.1111/j.1365-2486.2012.02644.x.
     
  10. skookerasbil
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    skookerasbil Gold Member

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    Hey Frank............saw a report his morning that mega-pythons are destroying all of the mammal life in the Everglades recently. Evidently, some genius is saying its global warming!!!


    This shit gets better and better all the time!!!:banana::banana::banana:
     

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