[Reader-list] not sceptics

[Nagraj Adve]

A new study shows 97% of climate scientists agree that we are changing
the climate. Photograph: John McConnico/AP

Trust is, perhaps, the most important word within the climate debate
at present. "Who do you trust?" is the question that hangs over every
discussion on the topic.

Do you trust the vast majority of climate scientists who claim that
anthropogenic greenhouse gas emissions are causing a clear and present
climatic danger? Or do you trust the much smaller band of sceptical
climate scientists who argue that there isn't a problem?

In much of our lives, we rely on the testimony and views of experts.
We do so when we feel ill and choose to visit the doctor. We do so
when we want to reduce our tax liabilities. We do so when we wish to
be ably represented in a court of law. We do so when a strange noise
appears from the engine of our car. We will often pay good money to
benefit from the many years of training and experience offered by
experts in their field - be they doctors, accountants, lawyers or
mechanics.

Climate science is a little different, it seems. A notably large – and
growing - proportion of society appears to be rejecting the expert
view of climatologists and choosing instead to place their trust
elsewhere. Needless to say, this has confounded many who work within
the climate sciences, but the causes are myriad and much discussed.

But an interesting new study published this week in the Proceedings of
the National Academy of Sciences throws some new light on the
"expertise gap" that some within the climate debate have noted exists
between the two increasingly divided factions.

The authors, led by Professor Steve Schneider at Stanford University,
have conducted an extensive literature review to establish the
identities, views and respective authority of 1,372 climate
researchers whose work "constitutes expertise or credibility in
technical and policy-relevant scientific research". One of the
principal goals of the study, say the authors, was to "examine a
metric of climate-specific expertise and a metric of overall
scientific prominence as two dimensions of expert credibility in two
groups of researchers". In other words, they wanted to provide a tool
to those outside the climate sciences to help them better assess which
experts to trust.

A broad analysis of the climate scientist community itself, the
distribution of credibility of dissenting researchers relative to
agreeing researchers, and the level of agreement among top climate
experts, has not been conducted and would inform future ACC
[anthropogenic climate change] discussions. Here, we use an extensive
dataset of 1,372 climate researchers and their publication and
citation data to show that 1) 97-98% of the climate researchers most
actively publishing in the field support the tenets of ACC outlined by
the Intergovernmental Panel on Climate Change; and 2) the relative
climate expertise and scientific prominence of the researchers
unconvinced of ACC are substantially below that of the convinced
researchers.

If you get the chance to read the study in full, please do. It
includes a detailed explanation of their chosen methodology, including
how they nullified the potential influence of "possible cliques" among
published scientists.

But the central idea seems to be that the more a scientist gets their
work published and cited in "climate-relevant publications", the more
credibility they should be accorded as an "expert" in that field.
Nothing revolutionary in this, of course: it's the way it works in any
academic discipline. However, it is still illuminating to see their
findings laid out so succinctly.

We provide the first large-scale quantitative assessment of the
relative level of agreement, expertise and prominence in the climate
researcher community. We show that the expertise and prominence, two
integral components of overall expert credibility, of climate
researchers convinced by the evidence of ACC vastly overshadows that
of the climate change sceptics and contrarians. This divide is even
starker when considering the top researchers in each group. Despite
media tendencies to present "both sides" in ACC debates, which can
contribute to continued public misunderstanding regarding ACC, not all
climate researchers are equal in scientific credibility and expertise
in the climate system. This extensive analysis of the mainstream
versus sceptical/contrarian researchers suggests a strong role for
considering expert credibility in the relative weight of and attention
to these groups of researchers in future discussions in media, policy,
and public forums regarding anthropogenic climate change.

One other interesting nugget from the study: "From the ~60% of
researchers where year of PhD. was available, mean year of receiving a
PhD. for UE [unconvinced by the evidence] researchers was 1977, versus
1987 for CE [convinced by the evidence] researchers, implying that UE
researchers should have on average more publications due to an
age-effect alone."

The study shows, however, that this is not the case. It's been noted
before, of course, that sceptical climate scientists tend to be
approaching retirement age, or are, in fact, already retired. What
does this tell us? That wisdom comes with age? Or is this evidence of
"retired man syndrome"; when scientists who have already seen the best
days of their career pass them by develop a contrarian view in an
attempt to seek validation and court attention?

Either way, I suspect this intriguing paper will court its own
attention given the distrust that permeates in this debate. As ever,
sceptics will reject it, whereas those who trust the message that 97%
of climate scientists are telling us will nod their heads in
acknowledgement.