From: schloerer@RZMAIN.RZ.UNI-ULM.DE ((Jan Schloerer))
Newsgroups: bit.listserv.biosph-l
Subject: Re: 50-Scientist Statement
Date: 14 Oct 92 21:25:28 GMT
Reply-To: "(Jan Schloerer)" <schloerer@RZMAIN.RZ.UNI-ULM.DE>
Comments: Gated by NETNEWS@AUVM.AMERICAN.EDU

Topic:   Climate change statement  released by the  Science and
         Environmental Project ("50-Scientist Statement")   -   long !

These and related opinions have been discussed at length in Usenet's
sci.environment this summer.  Readers of sci.env  or people just not
interested in the climate debate are kindly requested to skip this.

Firstly, thanks to Jeremy Whitlock for posting the text.  Believe it
or not, up to now I had only the list of signatories, among whom the
two most highly respected active reserarchers are :
     Richard Lindzen,  a meteorologist at MIT
     Hugh Ellsaesser,  a climatologist at Lawrence Livermore
                       National Laboratory
Except for these, active first rate research climatologists with an
international reputation are absent from the list. There is Fred Singer,
who seems still to maintain that there is no manmade problem with the
stratospheric ozone layer, and who has been one of the 'inputs' to
Dixie Lee Ray's book  "Trashing the Planet".  There are Robert Balling,
Patrick Michaels and Sherwood Idso, some climate change skeptics
frequently appearing in the media.

The political part of the statement is a matter of values.  One may dis-
agree whether action should be taken now, and it is true that there are

> activists ... pushing ahead with drastic policies ...

Anyway, this statement is misleading. There are not only advocates of
drastic policies, but also quite a few people who propose that one
should start with a "no-regrets policy", for which other economic and
environmental reasons make sense, whether or not climate change will
turn out to be serious.  I, for one, do not consider the European
Community's proposal to limit carbon dioxide emissions to 1990 levels
by the year 2000 as a "drastic policy".

> Agriculturalists generally agree that any increase in carbon
> dioxide levels from fossil burning has beneficial effects on
> most crops and on world food supply.

This is wrong.  In fact, we presently simply do not know to which extent
CO2 fertilization is going to happen under real life conditions.  The
1992 IPCC Supplement  (short version, WMO-UNEP, Geneva, February 1992)
states on page 36:
   "Research continues to address the relative importance of direct
   and indirect effects of CO2, in combination with a rise in
   temperatures, on future crop production. While some scientists
   emphasize enhanced photosynthesis and more efficient water use
   seen in controlled settings, others are sceptical that these
   benefits will be seen in farmer's fields under changing climate
   conditions."
Some recent work casting doubt on the ubiquity of CO2 fertilization :
   Fakhri A. Bazzaz  &  Eric D. Fajer, Plant life in a CO2-rich world,
      Scientific American 266,1 (Jan. 1992), 18-24   (a readable
      overview of the uncertainties)
   Richard J. Norby,  Carla A. Gunderson,  Stan D. Wullschleger,
      E.G. O'Neill  &  Mary K. McCracken,   Productivity and
      compensatory responses of yellow-poplar trees in elevated CO2,
      Nature 357 (28 May 1992), 322-324
   Christian Ko"rner  and  John A. Arnone III,   Responses to
      elevated carbon dioxide in artificial tropical ecosystems,
      Science 257 (18 September 1992), 1672-1675


> The majority of scientific participants in a survey (summer 1991)
> agreed that the theoretical climate models used to predict a future
> warming cannot be relied upon and are not validated by the existing
> climate record.  Yet all predictions are based on such theoretical
> models.

Not  "all predictions are based on such theoretical models".  To some
extent, the predictions are based on physics and on observations.
For instance, the change in radiative forcing induced by a doubling
of CO2 can be calculated; from my memory it's some 4 W/m^2.  The water
vapour feedback under clear sky conditions, which tends to enhance the
CO2 effect, has been determined observationally by Raval and Ramanathan
(Nature 342, 1989, 758-761)  -  a result accepted by most climatologists
except by Richard Lindzen and some of his adherents. Taking into account
recently emerging possible cooling effects due to manmade sulphate
aerosols and to ozone depletion by halocarbons,  "the existing climate
record"  and  "the theoretical climate models"  do not disagree so very
much  (T.M.L.Wigley & S.C.B.Raper, Implications for climate and sea
level of revised IPCC emissions scenarios, Nature 357, 28 May 1992,
293-300, fig. 3).  Of course, there still remain a lot of uncertainties,
perhaps the single largest uncertainty being the behavior of clouds
as the temperature rises.  On the other hand, except for the possibly
negative and possibly quite strong cloud feedback, most of the feedbacks
researchers have been able to imagine tend to enhance the warming.
And many of these feedbacks are not yet included in climate models.

Technical details aside, perhaps some results of two recent polls can
help to put things into perspective.  According to Scott Bennett
(bennett@mp.cs.niu.edu),  who posted this to sci.environment in July,
social scientists at the State University of New York at Albany conduc-
ted a poll on scientists involved in climate research. The results were
released in March 1992  and reported in the  30 May 1992  issue of
Science News, in its "Earth Sciences" column :

             "Climate change:  A diversity of views"

       "A poll of scientists involved in climate research reveals sub-
   stantial disagreement over predictions on global warming.  At the
   same time, the researchers do not advocate delaying action on the
   issue.
       "Conducted by social scientists at the State University of New
   York at Albany, the poll, released in March, queried 118 scientists,
   almost all of whom had participated in some activity related to
   climate change research.  The pollsters selected respondents through
   a computer-based network that primarily serves oceanic and
   atmospheric scientists.
       "One section of the poll addressed the projections given by the
   Intergovernmental Panel on Climate Change (IPCC)--an international
   group of over 100 scientists that sought to provide a global consen-
   sus report for policymakers.  The IPCC estimated that the global
   average temperature would warm by about 0.3 deg. C per decade, with
   an uncertainty range of 0.2 deg. C to 0.5 deg. C per decade.  The
   results of the poll show that roughly a third of the scientists
   had views closely matching the IPCC estimate. Another third felt
   less certain; they attached a wider range of possibilities to the
   projected warming rates. A smaller group thought the IPCC projected
   rate of warming was too high.   [Note: In 1992, the IPCC has slightly
   reduced its projected warming rate, due to the possible cooling
   effects of sulphate aerosols and ozone depletion, see above.]
       "The researchers, however, showed more consensus on a policy-
   related question.  Roughly three-quarters of those polled disagreed
   with the statement:  '...the current uncertainties are such that a
   delay in taking action is the proper policy.'"

According to Phil Geller (philg@net.com),  who posted this to sci.env
in September,  another poll was performed by Gallup in late 1991 on
behalf of the Washington-based  Center for Science, Technology and
Media (CSTM), a nonprofit organization devoted to clarifying the dialogue
between scientists and engineers, and the general public.  Scientists
from the American Meteorological Society and the American Geophysical
Union were surveyed.  The press release was dated 2/13/92.  The contact
at CSTM is Regina Lapierre, (301) 728-9602, fax: (301) 718-7806.

Altogether, 400 scientists were interviewed.  The following responses
come from a subset of 152 scientists directly involved in research in
global climate science.  Four of the questions were:

"Do you think that global average temperatures have increased during
the past 100 years?"  (yes or no)
   16 %  of the 152 said "no"  to this question.  Respondents answering
                               "yes" were asked next :
"In your opinion is the warming measured over the last 100 years within
the range of natural, not human-induced fluctuation?"  (yes or no)
   37 %  of the 152 said "yes"  to this question
   17 %  of the 152 said "no"
   30 %  of the 152 were uncertain

"In your opinion is human-induced greenhouse warming now occurring?"
   67 %  of the 152  said "yes"  to this question.  If the answer was
                                "yes" respondents were asked :
"Do you think that currently available scientific evidence
substantiates its occurrence?"
   47 %  of the 152  said "yes"  to this question, that is, 70 % of
                                 those saying "yes" to the previous
                                 question.

Thus many scientists do not believe any warming trend over the past
100 years can be explained as resulting from human activity. But most
scientists involved in research in this area do believe human-induced
global warming is occurring now.  By the way, the results of this poll
were distorted by some "interested" journalists.  Which was why the
topic appeared in sci.environment.  The poll was also mentioned in
Nature 356, 2 April 1992, 369:

   "Who is winning this war of words ?  The ... [CSTM] ... has found
   that the sceptics show up more in the press than they do in the
   scientific community.  Although about 70 % of researchers  ...
   thought that global warming was under way, according to a survey
   by the centre, only about half of the scientists quoted in newspapers
   such as the Washington Post and the Wall Street Journal held
   that view.  PR, in short, works."


Jan Schloerer          schloerer@rzmain.rz.uni-ulm.de
Klinische Dokumentation           Uni Ulm
Postfach 3880     DW-7900 Ulm     Germany
Comments: Gated by NETNEWS@AUVM.AMERICAN.EDU