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  • levycarni levycarni Aug 27, 2013 12:54 PM Flag

    Humans’ complicity in climate change can’t be ignored

    NEXT MONTH, the international arbiter of the scientific consensus on global warming will release its latest evaluation of the state of the research. A few will dismiss the Intergovernmental Panel on Climate Change’s (IPCC) findings as overwrought alarmism. But a draft leaked to reporters last week indicates that, for most people, the report will serve as another stern warning about the risks of continuing to pump carbon dioxide into the air.

    The scientists are set to claim that the increasing amount of greenhouse gases that humans have emitted into the atmosphere has almost certainly been the chief driver of the warming of the planet over the past half-century, a finding to which they ascribe 95 percent confidence. That’s the level of likelihood researchers typically consider robust enough to justify drawing very strong conclusions.

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    • Sheeple.
      There has been no warming in over 200 months.

    • The IPCC contradicts itself over the medieval warm period

      Page 9 of the AR4 SPM says that "Palaeoclimatic information supports the interpretation that the warmth of the last half century is unusual in at least the previous 1,300 years". The relevant chapter of the main WG1 report is chapter 6, "Paleoclimate", and in particular section 6.6, "The last 2,000 years". Although the IPCC does acknowledge some warming in medieval times, Box 6.4 on page 469 says "However, the evidence is not sufficient to support a conclusion that hemispheric mean temperatures were as warm, or the extent of warm regions as expansive, as those in the 20th century as a whole, during any period in medieval times".

      But, ironically, the data used by the IPCC in fact supports exactly this conclusion! Here is their Figure 6.10b, showing various 'proxy reconstructions' of temperature in the Northern hemisphere. Notice that these show a clear temperature maximum around 1000 AD, corresponding to the medieval warm period (MWP):

      Thus, the IPCC's own data shows a clear MWP around 1000 AD, and shows that the MWP was as warm as the late 20th century, completely contradicting the statements above from chapter 6 and from the SPM.


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