Geoscience Reference
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various global change processes, will likely
be falsely characterized as further evidence
of the ipcc's ineptitude and even fraud.
Elizabeth Kolbert writes: “No one has ever
offered a plausible account of why thousands
of scientists at hundreds of universities in
dozens of countries would bother to engi-
neer a climate hoax. Nor has anyone been
able to explain why Mother Nature would
keep playing along; despite what it might
have felt like in the northeast these past few
months, globally it was one of the warmest
winters on record.”
In ipcc's 4th Assessment Report (2007),
or ar4, the panel committed an editorial
error by stating that sea level would rise
between seven and twenty-three inches
by 2100,
not counting the contribution of the
melting ice sheets
. The absence of the ice
sheet contribution was duly but not clearly
noted in the text of the report. Some who
read this report misinterpreted the rise of
seven to twenty-three inches as being the
expected total rise. Others among the de-
niers have chosen to use these numbers to
minimize the potential importance of sea
level rise. The failure of the ipcc to include
the ice sheet contribution in its forecast
was regrettable, since clearly the melting
of ice sheets will have a significant impact
on sea level rise.
atmospheric warming, permafrost melting,
ice sheet degradation, and sea level rise is
a perilous process. Extensive field observa-
tions must provide the main basis for pro-
jections, but beyond fifty years out, math-
ematical models prevail. It is our belief that
scientists sometimes place too much faith
in mathematical models.
There are two kinds of mathematical
models, quantitative and qualitative. Quan-
titative models provide a number by asking
where, when, and how much. Qualitative
models provide an understanding by ask-
ing how, why, and what if. Global change
models, taken qualitatively, have provided
a critical understanding of the process of
change, have given estimates of direc-
tion and orders of magnitude, and have
answered numerous “what if ” questions.
Taken quantitatively, models are another
matter. As the discussion above indicates,
there are a large number of uncertainties,
certainly enough to make anyone nervous
about the various numbers associated with
the global warming phenomenon. For ex-
ample, James Hansen's claim that an atmo-
spheric CO
2
concentration of 350 parts per
million marks an irreversible global change
tipping point is most difficult to defend. A
tipping point may well exist, but a precise
number is simply not justifiable in the con-
text of so many uncertainties.
Another example of overreaching in
mathematical models was the statement
made by global change scientists testifying
before Congress in 2007. They observed
that according to models, we have ten to
mathematical models
Much praise and criticism is showered upon
mathematical models (computer models).
Accurate prediction of future trends in
