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a head in the late 1990s in the so-called 'hockey stick controversy' in the
United States, while the 'Climate-gate' and 'Glacier-gate' incidents a decade
later kept the, by then flickering, flame of scepticism alive (see
Box 7.3
).
BOX 7.3
CLIMATE CHANGE
The IPCC's periodic 'assessment reports' sift, sort and synthesise the
findings of thousands of scientists worldwide whose research focusses
on one or other aspect of atmosphere-earth surface relationships.
These reports have arguably been
the
principal means of communi-
cation between climate scientists and the rest of us. The second report
(IPCC, 1995) concluded that 'the observed trend in global mean tem-
perature over the past 100 years is unlikely to be entirely natural in
origin' (p. 412). The third report (IPCC, 2001) reiterated this obser-
vation and presented evidence of a 0.6
◦
C increase in global mean
temperature during the twentieth century. The fourth report (IPCC,
2007) stated that warming of the global climate system is 'unequivocal'
and revised the 0.6
◦
Cfigureupto0.74
◦
C. It stated that the observed
warming was almost certainly due to GHG emissions resulting from
human activity. Because so much research by so many different sci-
entists is reviewed in the assessment reports, the findings indicate a
durable consensus within the heterogeneous epistemic community that
the reports have, in effect, created.
Research by Professor Michael Mann (of the Pennsylvania State Uni-
versity) and colleagues featured prominently in the third report. Mann
et al.
(1998, 1999) had examined large sets of existing 'proxy data' for
past northern hemisphere temperature patterns going back to 1400 and
1000. Using a novel statistical technique to identify associations and
patterns, and supplementing proxy data with more recent temperature
observations, the authors concluded that there was a clear, and hitherto
unmatched, increase in temperature from the late nineteenth century.
This conclusion was represented in a two-dimensional graph showing
time on the horizontal axis and temperature on the vertical axis. The
graph became known as the 'hockey stick diagram' because centuries
of relative temperature stability resembled a flat 'handle', while the
sharp twentieth-century upward curve resembled a 'blade'. The dia-
gram featured prominently in the publicity events organised by the
IPCC to launch the third assessment report. According to science ana-
lyst Reiner Grundmann, 'after 2001
[it] became
the
icon for the
IPCC and global anthropogenic climate change' (2012: 15, emphasis
added).
...
