The conviction that humans are responsible for changes in the world's climate, is in contention
THE conclusions of 11th plenary meeting
of the Intergovernmental Panel on
Climate Change (ipcc) held at Rome,
Italy, in December 1995, continue to be
debated. The most contentious declaration made by the ipcc states that the
"Human influence (in bringing about
global climatic changes) is clearly discernible". It is alleged that the ipcc's
summary report which presents the
proceedings of the meet in a mitshell,
has selectively highlighted certain issues
while choosing to ignore others.
Concerns over the misleading nature of
information provided by the summary
report are great because it is the most
widely-read document brought out by
the ipcc's Second Assessment Report
documents (Ecoal, April 1996).
A variety of reasons have generated
this criticism of ipcc's summary report.
Most of the ipcc's climate change forecasts are based on computer models
(general circulation models), and have
ignored the temperature measurements
of the lower troposphere (the lowest
region of the atmosphere extending
from between eight and 18 kin), which
have been made by satellites and
radiosondes (weather balloons).
The latter had been presented by the
ipcc's working group. They indicate a
slight overall decline in temperature
since 1979, the year when constant satellite monitoring was initiated. On the
other hand, measurements of global
surface temperature; indicate a slight
warming over the same period.
Fred Singer, president of the Science
and Environmental Policy Project,
believes that the ipcc's report is deceptive. According to him, the report correctly states that the climate has warmed
by 0.3'c to 0.6'c, in the past century.
However, it does not mention that there
has been little if no warming in the last
50 years - a time when about 80 per
cent of the greenhouse gases were added
to the atmosphere. In this context he
mentions that the findings Of NASA'S
(National Aeronautics and Space
Administration, us) satellites - regarded as true global measurements -
show no warming at all; in fact, they
report a cooling trend. The NASA data
has been overlooked by the ipcc. Singer
also ciriticises the ipcc for failing to mention the discrepancy in results. "With
climate models lacking validation, why
should we trust any of the forecasts
about say future warming or rise in sea
levels? And why should we be using
them as a basis to formulate costly policies ?" he questions.
Some scientists do admit that satellite data does not always give an accurate
picture of surface temperature, but
when'its trends are compared with
radiosonde data, the two match rather
well. Radiosonde measurements over
the polar region, in the past 40 years,
indicate no evidence of warming. Singer
draws attention to the fact that though
there is a common consensus among
scientists about the rise in surface temperatures, the ipcc is itself sceptical about the legitimacy of surface temperature records. These doubts are listed in
their 1992 report with the reasons for
inefficiency (incomplete spatial coverage, changes in schedules, practices and
station location and occurrence of
urbanisation around many stations,
among others).
Accu-Weather, a leading commercial weather forecasting firm states that
hemispheric satellite data, rather than
surface temperature data, must be taken
as a representative of global atmospheric temperature. The former is more uniformly distributed and covers a larger
surface. They feel that if there were any
significant changes taking place on the
surface, they would be manifested in the
lower troposphere too and satellites
would be recording the same. And till
now, no such trends have been observed
in satellite data. Hence, according to
Accu-Weather, not much could be happening at the surface level. The ipcc also
fails to mention some of the positive
aspects of global warming. For instance,
the number of droughts faced by the
American heartland may be rising but
conditions are getting more moist.
The summary for policymakers also
says, "Our ability to quantify human
effect on climate is currently limited by
uncertainties in key factors including
long-term natural variability and time
evolving patterns of radiative forcing by
greenhouse gases and aerosols". This
point is totally overlooked in the next
paragraph which concludes by saying
that "Taken together, these results point
towards a detectable human influence
on global climate."
What surprises most scientists is
that despite the existing uncertainties,
the ipcc has taken a formal stand to
'confirm' the human hand in global
warming. Robert Balling, director of climatology at the Arizona State
University at Tempe, us, said that policymakers do not have the time to go
through the entire document and will
instead read the summary report or rely
on the media. Therefore, he stresses the
point that the information supplied to
the media should be correct and complete. News accounts misinterpret reality when they use selective information.
They either make exaggerated claims or
miss out the small but important details.
Ultimately, what goes beyond doubt is
that we are still in the dark about the
uncertainties in climate.
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