“A disservice to the scientific method”: climate scientists take on Richard Lindzen
- 04 Apr 2012, 14:41
- Verity Payne
A team of UK climate experts has published a
critique of a talk given by climate skeptic scientist Richard
Lindzen a few weeks ago. The event was organised by the Campaign To Repeal the
Climate Change Act.
Lindzen, a Professor of Meteorology at the Massachusetts
Institute of Technology, was speaking at the House of Commons in a
meeting chaired by Christopher Monckton.
While the authors of the critique could agree with Lindzen on some
grounds, they also found some pretty glaring inaccuracies in his
talk.
Lindzen has published a
large body of peer-reviewed work on climate change, but
his work remains disputed. It's very popular with the skeptic end
of the
media and he is also member of the academic advisory council to
Lord Lawson's Global Warming Policy Foundation.
His speech was
criticised by the blog Skeptical Science. Climatologist Dr
Gavin Schmidt also pointed out
flaws in his presentation of temperature data at the blog
Real Climate, resulting in an
apology from Lindzen.
Now, several UK experts have got in on the act, offering their own
critique of Lindzen's speech. They are climate physicists
Professor Sir
Brian Hoskins at Imperial College; Professor John
Mitchell, of the University of Reading and the UK Met Office;
Professor Keith
Shine, University of Reading; Professor
Tim Palmer, University of Oxford; and Professor
Eric Wolff, British Antarctic Survey Science Leader.
Points of agreement
The critique starts with the key points on which Lindzen and the
UK experts agree. They welcome Lindzen's acceptance of some well established
'knowns' of climate science, including:
"There has been a large increase of
atmospheric concentrations of carbon dioxide and
other greenhouse gases due to emissions resulting from human
activity over the past 150 years [...] Global average surface
temperature has very probably warmed by about 0.7°C in the
same period [...] Increasing carbon dioxide alone, and in the
absence of climate feedbacks, should cause about 1°C warming for
each doubling."
"'Uncertain' doesn't imply 'unknown'"
The scientists also agree with Lindzen that scientists should base
their arguments on "physical reasoning and data", and that
uncertainties should not be exaggerated or ignored - indeed
these points are the ground rules by which scientists
operate.
Where they disagree is on Lindzen's inference that scientific
uncertainty means scientists are ignorant about some key issues,
implying we then don't have to be concerned.
One of Lindzen's favourite arguments seems to be his criticism of
our knowledge of cloud feedback processes. Climate models suggest a
weak to moderate positive cloud feedback, but there are
uncertainties associated with how this will change in the
future.
In his
speech Lindzen suggests that these uncertainties mean "we don't
know if there is a problem". The team of experts disagree,
saying:
"[Lindzen] is right to draw attention to
uncertainties in climate change feedbacks e.g. associated with
clouds. However, it is wrong to infer from this that we know
nothing about these feedbacks. Contemporary science suggests
unambiguously that there is a substantial risk that these feedbacks
will lead to human induced surface temperature change considerably
larger than 1 °C in global average this century and beyond."
According to the paper, Lindzen makes similar errors in his
discussion on sea level rise, reconstructions of solar activity,
and climate sensitivity - how much the world's average temperature
would rise from a doubling of carbon dioxide in the
atmosphere.
Inconsistencies in Lindzen's arguments
The team also point out some pretty glaring inconsistencies in
Lindzen's take on some climate topics, for example:
"There is an interesting dichotomy in
[Lindzen]'s line of argument between the implication in the rest of
the presentation that the climate is rather insensitive to change,
and the observation that, on glacial interglacial scales,
even very small changes in energy input led to massive change."
They say Lindzen is "not consistent in his discussion of the
accuracy of past temperature data" or of climate models.
And elsewhere, the team say, Lindzen makes claims that are simply
wrong:
"[Lindzen] claims that the derived
sensitivity of climate to a doubling of CO2 is less than 1°C, based
on the assumption that all the observed warming is due to
atmospheric greenhouse gases. This claim would be wrong even
without this assumption [...] The assumption itself is
unjustifiable as it neglects other mechanisms that drive climate
change."
Lindzen "does a disservice to the scientific
method"
The team sums up Lindzen's presentation, saying:
"A pervasive aspect of [Lindzen]'s
presentation was the conflation of uncertainty with ignorance; in
his view, because we are uncertain about some aspect, we therefore
know nothing about it and any estimate of it is mere guesswork. In
this way we believe [he] does a disservice to the scientific
method, which seeks to develop understanding in the face of
inevitable uncertainties in our knowledge of the world in which we
live. The scientific method has served society well for many
hundreds of years, and we see no reason to doubt its validity for
trying to quantify the risk of climate change and its impacts on
society this century."
They go on to point out that Lindzen's arguments are not
anywhere near sufficient to discount man-made climate change:
"[...] We reassert that there is a
substantial risk of human-induced climate change considerably
larger than 1°C in global average this century and beyond. There is
nothing in [Lindzen']s talk to cast doubt on the existence of this
risk."
Scientists in the service of politics?
At Real Climate, Schmidt
points out the value of questioning established norms of
climate science:
"[Lindzen] has, in times past, raised
interesting critiques of the mainstream science. None of them,
however, have stood the test of time - but exploring the issues was
useful."
The two responses however argue that Lindzen's statements on
climate science go beyond questioning the science, instead
presenting scientific uncertainty as ignorance and meanwhile
advocating against climate policymaking. It seems strange to us
that Lindzen is so vocal about criticising climate
scientists for being politicised while speaking at an event
organised by a political campaign against the UK's Climate
Change Act.
The scientists
respond to this element of Lindzen's presentation,
concluding:
"It is up to policymakers, not
scientists, to decide whether governments should take concerted
mitigating action to try to reduce [the risk of human-induced
warming above 1 degree celsius]. On this we do not
comment."
Tim Palmer, one of the scientists who wrote this latest
response, told us he felt it was important to respond in this case
because Lindzen is "an established atmospheric scientist and hence
likely to have some influence". He and the other scientists thought
it was important to make it clear to UK policymakers that Lindzen's
view that the threat of substantial climate change is minimal runs
"completely counter to the view of almost all who work actively in
the field."
Update 13/04/12 09:45: Lindzen has
responded to the scientists' critique at the website of climate
skeptic lobby group the
Global Warming Policy Foundation.