date: Tue Jul  5 10:15:39 2005
from: Phil Jones <p.jones@uea.ac.uk>
subject: FW: Your graph regarding global temperature anomaly
to: heino.schmid@aon.at

      Dear Heinrich,

           There are a multitude of explanations of the course of temperature change
    during the 20th century. These are discussed in the various IPCC reports.
         The warming from 1915 to about 1940 is generally believed to be
    due to a slight increase in solar output and a reduction in volcanism. The recent
    warming from 1975 is due to the build-up of greenhouse gases, as they
    begin to dominate over sulphate aerosol releases.
        The slight cooling from 1940 to 1975 is thought to be due to industrial
    development (using lots of dirty coal) increasing aerosol emissions. WWII
    is not thought to have had any impact.
        On all the above there is natural variability which could have caused
    some of the changes even without any external forcing (greenhouse gases,
    aerosols, solar, volcanoes etc) as we have had warm and cold decades in
    the past when there was little changes in external influences.
       I hope this short reply helps. The best things to read are the IPCC
    reports.
    Regards
    Phil

     -----Original Message-----
     From: Heinrich Schmid [[1]mailto:heino.schmid@aon.at]
     Sent: Sunday, June 26, 2005 8:35 AM
     To: cru@uea.ac.uk
     Subject: Your graph regarding global temperature anomaly
     Sir, viewing the graph one recognizes a significant change in direction at
     about the year 1910. Then there is another change at about 1940 and again at
     about 1975. This period between 1940 and 1975 could be interpreted as being
     due to the negative forcing of the dust and smoke created during WWII. Your
     response would be appreciated. This interpretation would have significant
     implications to our understanding of global warming
     Sincerely
     Heinrich Schmid
     Kellertal 171
     A-6410 Pettnau
     Austria

   Prof. Phil Jones
   Climatic Research Unit        Telephone +44 (0) 1603 592090
   School of Environmental Sciences    Fax +44 (0) 1603 507784
   University of East Anglia
   Norwich                          Email    p.jones@uea.ac.uk
   NR4 7TJ
   UK
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