]]]]]]]]]]        HAS THE GLOBE REALLY WARMED?       [[[[[[[[[[[[
                                                       (11/21/89)
   [From Technology Review 92(8):80 (November/December 1989)]

             [Kindly uploaded by Freeman 10602PANC]

   Since the mid-nineteenth  century, merchant-marine captains of
all nations have been required  to log air and water temperatures
every  six  hours  for  weather  services  such  as  the  British
Meteorological  Office.  Crews  on each  watch have  hauled water
from   the  sea   in   standard  buckets,   dipped   in  standard
thermometers, recorded the data, and, generally, radioed it back.
The  result  is  an incredible  storehouse  of  information about
global temperatures since the Industrial Revolution.
   Reginald E.  Newell, Jane  Hsiung, and  Wu Zhongxiang  of MIT,
along with colleagues from the  ``British Met,'' as they call it,
have collected  and analyzed  these data.   MIT Press  intends to
publish them in the Global  Ocean Surface Temperature Atlas.  One
of the most striking results suggested  by the data is that there
appears to have  been little or  no global warming  over the past
century.
   The  advantage  of  ocean  readings   is  that  they  are  not
contaminated by urbanization: the  growth of structures and roads
even in the  small towns where many  weather stations are located
can  raise temperatures,  Newell explains.   Unfortunately, ocean
readings  are not  entirely reliable  either.   One of  the chief
problems  is  that  prior  to  World  War  II,  the  buckets  for
collecting water were made of canvas.   As it was hauled onto the
deck,  the water  could  be cooled  by  wind and  heated  by sun.
Christopher Folland of the British Meteorological Office and Jane
Hsiung attempted  to correct  for such  problems, for  example by
measuring the cooling of the buckets at different wind speeds.
   Gauging long-term  temperature change  required more analysis.
First,  Newell,  Hsiung, and  Wu  needed to  measure  the cooling
caused when volcanoes inject dust  and gases into the atmosphere.
They discovered  an intriguing  piece of  work that  measures the
atmospheric ``turbidity''  from the  dust over  the past century.
Beginning in the  late 1800s, weather  stations have used devices
known as Campbell-Stokes sunshine recorders  that burn a track in
a  paper card  each  day, indicating  how  long the  sun  was up.
Researchers at the University of  Mainz in West Germany collected
and  analyzed  numerous  such   cards,  noting  particularly  the
beginning and  end of the  burn, which correspond  to sunrise and
sunset.  Whenever  atmospheric turbidity  rose, the  burn started
later  and  ended  earlier.  The  weather  station  in Sonnblick,
Austria, almost unaffected by urban  pollution at an elevation of
3 kilometers in the Alps, provides  a record of turbidity back to
1887.
   Newell, Hsiung,  and Wu also  assessed the  periodic change in
tropical temperatures caused by the El Ni$o-Southern Oscillation,
a complex of  ocean and air currents.   Factoring out the effects
of the  El Ni$o-Southern  Oscillation and  the cooling  caused by
volcanoes,  they found  that global  temperatures have  warmed by
only 0.2xC over  the past century, which  is within the estimated
margin  of error.   In other  words, the  results leave  open the
possibility that there has been no warming at all.
   In  a paper  based on  the same  data in  Geophysical Research
Letters,  Nicholas E.  Newell (Reginald  Newell's son)  joins the
other  researchers to  examine a  third temperature  variation: a
roughly 22-year  cycle of warming  and cooling  that has occurred
since 1856, when  the marine data  begin.  This may  be caused by
the 22-year solar magnetic cycle, during which the sun's magnetic
field changes  polarity and then  returns to  its original state.
The  magnetic cycle  is reflected  in changing  sunspot patterns.
When the authors  subtract from the  basic temperature record all
cycles of less than 26 years  -- the chief one being this 22-year
warming-and-cooling  pattern   --  they   find  ``no  appreciable
difference'' between temperatures in 1856 and 1986.
   Both  studies  are  at odds  with  some  other  research.  For
example, using  land data that  attempt to factor  out effects of
urbanization, James  Hansen of  NASA Goddard  Space Flight Center
and Sergej  Lebedeff of Sigma  Data Services  Corp. conclude that
the globe has warmed 0.5 degrees C to 0.7 degrees C over the past
century.
   The conflict is far from resolved.  Unfortunately, despite all
the models of how global  climate may change, there is relatively
little  funding for  research on  the actual  record.  A  case in
point:  though the  Global  Ocean Surface  Temperature  Atlas has
passed peer  review and  been accepted  by MIT  Press, so  far no
sponsor has been willing to  provide the modest subsidy that such
a technical book  often requires for publication  -- it this case
$60,000.

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