Lord Turnbull's GWPF briefing paper 'The really inconvenient truth' suffers from basic factual innaccuracies
Andrew Turnbull's recent briefing paper [PDF]
for the Global Warming Policy Foundation,The Real Inconvenient
Truth or "It Ain't Necessarily So" has made a small splash in the
press this week.
Timed to coincide with the government decision on the Committee
on Climate Change's carbon budget recommendations, Turnbull himself
summarised the paper on the pages of the Telegraph, and James
Delingpole lauded it in a blog for the same paper.
The 15 page briefing paper discusses the IPCC's assessment of
climate science and the UK policy response. In the Foreword, Lord
Lawson praises Turnbull's work as a 'dispassionate but devastating
critique', and a 'measured verdict'.
But how reliable are its conclusions? Sadly, they are not
reliable at all. Below are a few examples of where Turnbull gets
things badly wrong, and one example of questionable quotation.
• The "Hockey Stick"
On the IPCC's assessment of historical temperatures, Turnbull
writes that "[i]n its Third Assessment (2003), the IPCC compared
its view to an ice hockey stick."
In fact, though the graph that has come to be known as the
"hockey stick" - because of its largely flat shape, with an upward
curve at one end - was included, a search of the IPCC website
reveals that the words "hockey stick" feature nowhere in the Third
Assessment Report. The Report was also published in 2001 - not, as
Turnbull states, 2003.
• Historic variability of temperature
Turnbull writes that:
"Many scientists believe that in the
IPCC's later reports the [temperature] fluctuations in the past
1000 years have been wrongly flattened out, underplaying a Medieval
Warm Period (1000 -1350 AD), followed by a Little Ice Age
(1550-1850), and the recovery from it over the last 150 years. This
alternative view indicates that our climate has been variable long
before the recent movements in CO2."
Later, he writes that:
"tracing the history back over millennia
... [e]fforts are made to splice together records of proxies such
as ice cores, tree rings, ocean sediments and also social history.
But the statistical manipulations of the data required make it
possible to achieve almost any result."
Still later, he writes:
"We need to acknowledge that there have
always been fluctuations in our climate. Rather that writing
natural forces out of the script, we need to build them into the
However, there is no "flatten[ing] out" or "splic[ing]" in the
IPCC's most recent (2007) report: rather, the multiple lines of
evidence from temperature reconstructions are
laid out side-by-side. It is also clearly not "possible to
achieve almost any result" from this data: they represent a range
of possibilities, with clear upper and lower bounds.
The section in which they feature is a discussion of "
Northern Hemisphere Temperature Variability" over the past
2,000 years - which explicitly notes "the underlying variability of
climate". Elsewhere, the IPCC notes that temperatures over the past
1,000 years are "punctuated by substantial shorter-term
Far from being subversive, the "alternative view" Turnbull
proposes is taken for granted by the IPCC and reflected throughout
• A conspiracy to cover up the Medieval Warm Period?
A simple graph showing a 'medieval warm period appeared in the
IPCC's First Assessment Report in 1990, but was revised in
subsequent reports to incorporate more recent research findings.
Turnbull proposes a particular theory to explain this revision:
"Early reports from the IPCC
acknowledged these fluctuations but, of course, they are
inconvenient to the AGW [man-made global warming] believers, one of
whom e-mailed another saying "We must get rid of the Medieval Warm
Period." Writing the MWP out of the script made it easier to claim
that present temperature levels were unprecedented."
A search of the CRU emails for the phrase "we must get rid"
turns up no results. In fact the phrase is a misquotation of one
used by David
Deming, a noted climate sceptic, anti-environmentalist and
the National Center for Policy Analysis - a right-wing
libertarian US think-tank which has received funding from the oil
company ExxonMobil and Koch Industries.
In 2006 Deming told
the US Senate Committee on Environment and Public Works he had
"received an astonishing email from a major researcher in the area
of climate change. He said, "We have to get rid of the Medieval
Warm Period."" The email Deming purported to have received was
never made public. Turnbull's quotation, then, is unsubstantiated,
misquoted and comes from a source entirely different from the one
he claims for it.
• The scientific consensus
Turnbull constantly challenges the idea that there is a
consensus that recent warming is man-made. He writes that: "[t]here
is huge controversy about the relative contribution of man-made CO2
versus natural forces", for instance - and that "[w]hat is
frequently described as a "consensus" is no such thing." Yet a 2004
of peer-reviewed journal articles found none contesting the
consensus position. Another, more recent (2009) peer-reviewed study
asked scientific experts the question: "Do you think human activity
is a significant contributing factor in changing mean global
temperatures?" As it concluded:
"It seems that the debate on the
authenticity of global warming and the role played by human
activity is largely nonexistent among those who understand the
nuances and scientific basis of long-term climate processes. The
challenge, rather, appears to be how to effectively communicate
this fact to policy makers and to a public that continues to
mistakenly perceive debate among scientists."
• Taking natural factors into account
"If CO2 were as important as many AGW
theorists claim, why has temperature not followed a steady upward
path? Immediately it becomes obvious that the increases of CO2 and
of temperature are poorly correlated and that one needs to bring
other factors into the story such as the sun, clouds and the way
heat is stored in, and distributed around the oceans."
CO2 and temperature would only have "followed a steady upward
path" if they were the only factors affecting climate. But -
perhaps unsurprisingly - climate scientists have not failed to
notice that the sun warms the earth, or that the sun's output
varies. The IPCC
notes, for instance, that "[t]he natural external factors that
affect climate include ... variations in solar output"; and
that "[t]he ocean has an important role in climate variability
The idea that climate scientists "[need] to bring other factors
into the story" is simply false: these factors are already an
integral part of the story. As the IPCC
demonstrates, models that take into account only natural
influences cannot explain the warming observed over the course of
the 20th Century: only those that include both man-made and
natural influences are able to do so.
• The mid-century decline in temperatures
Turnbull writes that in the last 150 years:
"unlike the rise in CO2 which has been
pretty steady ... Temperature rose rapidly from 1900-1940 when the
CO2 increase was modest, followed by a small drop in temperature
between 1940-70 despite CO2 growth being particularly strong at
this time. Between 1970 and the late 1990s both CO2 and temperature
increased strongly together. … If CO2 were as important as many AGW
[man-made global warming] theorists claim, why has temperature not
followed a steady upward path?"
This argument was one of those used by Martin Durkin in his
Channel Four film "The Great Global Warming Swindle" - widely criticised by
climate scientists, including in a comprehensive rebuttal submitted
to Ofcom. However, a more sophisticated view of the factors
affecting temperature rise over the twentieth century provides a
clearer picture which does not challenge the importance of CO2 in
relation to rising temperatures.
The post-1940 decline in temperatures appears to be linked
increasing emissions of atmospheric aerosols - another man-made
pollutant emitted alongside greenhouse gases - which serve to
"mask" the latter's warming effect. When Europe and the US clamped
down on aerosol emissions, temperature rise resumed.
The 1940-70 dip was also sharpened by a
change in the methods used to collect and measure oceanic
temperature samples after 1945. During the second world war, US
ships measured the temperatures of the seawater used to cool their
engines - which tended to result in higher temperature readings. UK
ships resumed this task after the war - but collected samples in
uninsulated buckets, tending to give lower temperature
Hence a more detailed view both
helps explain temperature patterns between 1940 and 1970, and
confirms the importance of CO2 as a driver of temperature rise over
the past century.
• Water vapour, clouds and feedbacks
In his discussion of the effects of clouds on climate, Turnbull
"A hotter atmosphere will hold more
water vapour. But does this automatically mean that there will be a
positive, i.e. amplifying, feedback effect? Not necessarily. Low
level cloud does have an insulating property but high-level cloud
also has what is known as an albedo effect, reflecting the sun back
into space, which is why cloudy days are cooler. The IPCC models
have assumed but not proven a strongly positive, i.e. amplifying,
feedback, but have ignored the possibility of negative feedbacks.
Some scientists such as Professor Lindzen of MIT argue that the net
effect could go either way."
The IPCC has not "ignored" this possibility - as a search of the
IPCC website reveals, they repeatedly
reference Richard Lindzen's writings on water vapour,
clouds and feedbacks. (However, it's worth noting that Lindzen
is a marginal figure within the field of climate science who diverges
from the scientific consensus on climate change.)
The IPCC also
note that "[i]n response to global warming, the cooling effect
of clouds on climate might be enhanced or weakened … Therefore,
cloud feedbacks remain the largest source of uncertainty in climate
sensitivity estimates" - explicitly discussing the possibility
Turnbull claims they have "ignored".
Water vapour and clouds are not synonymous, however - and,
as the IPCC concludes, the weight of available evidence
strongly supports the idea that water vapour will reinforce global
"Significant progress has been made
since the TAR [Third Assessment Report, 2001] in understanding and
evaluating water vapour and lapse rate feedbacks … New tests
have been applied to GCMs [global climate models], and ... [n]ew
evidence from both observations and models has reinforced the
conventional view ... Taken together, the evidence strongly favours
a combined water vapour-lapse rate feedback of around the strength
found in global climate models."
• The opinion of David Whitehouse
At another point, Turnbull cites the words of "David Whitehouse,
the former BBC Science Correspondent":
"How many times have you seen, read or
heard some climate "expert" or other say that mankind's greenhouse
gas emissions are largely responsible for the unprecedented warming
we have seen over the past century, and especially over the past 30
years. It is as if, to some, nature has stepped back, leaving
mankind to take over the climate. In reality, whatever one's
predictions for the future, such claims are gross exaggerations and
misrepresentations. Natural and human climate influences mingle and
even today the natural effects dominate."
Lord Turnbull does not mention in the text that David Whitehouse
is currently the Global Warming Policy Foundation's Science Editor,
and hence that this is a case of a Global Warming Policy Foundation
report citing its own staff as experts, without making clear their
Whitehouse's material has also been repeatedly challenged. Bob
Ward of the LSE's Grantham Research Institute on Climate Change and
the Environment, for instance, recently
criticised a GWPF webpage authored by Whitehouse for
"containing 90 errors and misleading statements".
As we have already seen, both natural and man-made effects are
taken into account by climate scientists, who have reached a
consensus that the warming over the last century is dominated by
the latter. There is little reason to disregard their opinion in
favour of that of David Whitehouse.
Nevertheless, even Whitehouse himself
accepted in 2007 that: "My own view on the theory that
greenhouse gases are driving climate change is that it is a good
This last paragraph of this blog was amended on 10June in
response to a comment from David Whitehouse. It originally stated
that Dr Whitehouse was 'recently forced to concede' that greenhouse
gases are driving climate change.