Geoscience Reference
In-Depth Information
The advice of climate science contrarians is to ignore the dangers in
the Climate Casino. To heed that advice is a perilous gamble.
UNATTAINABLE CERTAINTY
I am often asked if, given all the uncertainties, we can be absolutely
sure that humans are causing rising temperatures and that this trend
will continue in the years ahead. The IPCC Fourth Assessment Report
answered this question as follows: “Most of the observed increase in
global average temperatures since the mid-20th century is
very likely
due to the observed increase in anthropogenic greenhouse gas concen-
trations.”
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Critics continue to attack these and similar conclusions. One ar-
gument is that scientists are not really 100 percent sure about global
warming. That is true. But a good scientist is never 100 percent sure of
any empirical phenomenon. This was explained by Richard Feynman
in a way that is humorous but very deep:
Some years ago I had a conversation with a layman about fl ying
saucers. Because I am scientifi c, I know all about fl ying saucers! I
said, “I don't think there are fl ying saucers.” So my antagonist said,
“Is it impossible that there are fl ying saucers? Can you prove that
it's impossible?”
“No,” I said, “I can't prove it's impossible. It's just very unlikely.”
At that he said, “You are very unscientifi c. If you can't prove it's
impossible, then how can you say that it's unlikely?” But that is the
way that is scientifi c. It is scientifi c only to say what is more likely
and what is less likely, and not to be proving all the time the possi-
ble and impossible.
To defi ne what I mean, I might have said to him, “Listen, I mean
that from my knowledge of the world that I see around me, I think
that it is much more likely that the reports of fl ying saucers are the
results of the known irrational characteristics of terrestrial intelli-
gence than of the unknown rational efforts of extra-terrestrial intel-
ligence.”
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