The Nature Editorial: 'Shooting the Messenger'
A Specially Commissioned Paper for The Lavoisier Group
The English-speaking world enjoys the benefit of two great
weekly science journals: Science and Nature. The
former is issued in the US by the American Association for the
Advancement of Science, and the latter is a commercial venture
Science is a greenhouse booster of long-standing, and
its view on this important topic was counter-balanced by a mildly-sceptical
editorial tone at Nature. But Dr Jekyll is no more. Now
that Sir John Maddox has departed the editorship, and that Macmillan
has been bought by German interests, Mr Hyde has broken loose.
The Nature editorial of 12 July 2001 (volume 412, page
103), ie, immediately prior to the opening of the Bonn
continuation of COP VI on 16 July, is terrible proof. It is entitled
'Shooting the messenger' and then sub-headed 'The Intergovernmental
Panel on Climate Change has a creditable record of developing
a scientific consensus and delivering it to policy-makers. What
its critics really object to are the facts'.
I will get back to the facts of IPCC's 'scientific consensus'
later. First, Nature is a good journal; although
I would say that, wouldn't I, having published in it (on palaeoclimatology).
But have you read anything half as Goebbelsian in a reputable
scientific publication as the editorial quoted below?
2. SHOOTING THE MESSENGER
It will be an unusually long quote, I am sorry to say; but
then, as you will soon see for yourself, this is no ordinary editorial.
It begins by introducing at once the Great Satan:
The drumbeat of diversionary noise that US coal and oil producers
have created around climate-change science has a certain inevitable
rhythm, all of its own. Take this year's events, for example
(although those of any one of the past 15 years would do). The
Bush administration, short of scientific advisers of its own
but keen to justify its premature dismissal of the Kyoto Protocol
on climate change ...
It then makes favourable reference to its Guiding Star:
The perennial charge against the IPCC is that its summary-making
process involves politicians and non-government organisations,
as well as scientists.... [But] the IPCC process is a markedly
modern one whose overall effect has been, on balance, to moderate
the findings of its various working groups...
And it makes disparaging reference to the morality of IPCC's
Why, then, is it embroiled in so much criticism? If the IPCC's
record is set against its critic's charges, it soon becomes apparent
that the answer to this question lies in the latter group's unscrupulous
determination to defy the facts on climate change to the bitter
Right from the outset, the approach of certain industrial
lobby groups in the United States has been to resist, resist
and resist again the mounting evidence ...
It then questions (my emboldment added) the qualifications
and motives of 'experts' who are not of the Cloth, ie scientists
whose perspective of climate-change is different from those who
are experts in atmospheric science sensu stricto.
To this end, they have championed specious scientific findings
and worked to establish a bogus scientific debate between their
own 'experts'---many of whom are not even atmospheric scientists---and
the consensus view of climate researchers. In doing this, they
have deliberately set out to take maximum advantage of media
gullibility, ensuring that stories on the problem include both
'sides' of the debate.
And it then mines a much-more-vituperative vein:
Science can only progress through its strong tradition of
debate and dissent. But this particular debate discredits the
notion of scientific dissent. Some of the climate-change dissidents
bring to mind the Aids dissidents ... Others resemble the tobacco-industry
The campaign to confuse and delude the US public on global
warming has had its successes, but has been less effective than
its originators would like to pretend. The public is not amused
by President Bush's dismissal of the Kyoto Protocol ...
A Paean to the Righteous concludes this amazing editorial:
The IPCC should continue its valuable work in the knowledge
that its integrity and adherence to the facts will ultimately
prevail, bringing credit to both its architects and participants.
It is reassuring to know that a great journal is keeping an
open mind on the complex and multi-disciplinary scientific issues
crucial to the future of humanity. Science is in good hands.
3. RUNNING DOGS OF IMPERIALISM
The editorial starts off on the right track. We are
witnessing here a battle between wealth creation---as practiced
in the twentieth century, based on the ready availability of affordable
energy from fossil fuels---best exemplified by the United States,
and anti-capitalist fundamentalism---in the form of the decarbonisation
of western economies---as advocated by IPCC.
Overstating things a bit, am I? Yes, perhaps so, but not nearly
as much as you may think. I have talked elsewhere about the potential
economic impact of the Kyoto Protocol (see my paper 'The Carbon
Challenge: should Australia decarbonise?' posted at Warwick
Hughes' new website).
In addition, the attention now being directed to a potential future
greenhouse threat---real or not---is already diverting money and
zeal from real-life, here-and-now, environmental needs.
4. SUMMARIES MODERATED
In the editorial, and in this analysis, we are talking about
the science of climate change. See if you think, as I do,
that Nature has allowed its apparent dislike of President
Bush, and of the coal and oil industries, to colour its appraisal
of IPCC and its science.
First, Nature makes the implausible claim that access
of politicians and NGOs to the summary-writing process is a moderating
influence on the conclusions of scientists as embodied in the
technical chapters of IPCC's reports.
I give below two examples where Nature is wrong.
4.1 SAR Summary for Policymakers
IPCC's Second Assessment Report 'Climate Change 1995:
the science of climate change' was the scientific underpinning
of the Protocol developed at Kyoto in 1997.
However, there is little chance that 'policymakers' around
the world, be they politicians or bureaucrats, could have read
this 572-page scientific report before they began negotiation
of the treaty. Instead, they would have relied on its 5-page Summary
To reach the Summary, policymakers would have passed
by way of a brief introductory statement---misleadingly asserting
that the report 'presents a comprehensive, objective, and balanced
view of the subject matter'. Then, over the page, they would have
encountered the Preface. This 1 1/3
pages contained but a single reference to climate-change science:
... that observations suggest 'a discernible human influence
on global climate', one of the key findings of this report, adds
an important new dimension to the discussion of the climate change
This attention-getting statement is repeated almost verbatim,
and again without elaboration, in the subsequent Summary for
Policymakers. However, those policymakers who had the time
to seek out more detail on this 'key finding' in the body of the
text, would have been disappointed.
The relevant chapter of the report is much more circumspect
in its manner of expression than is either the Preface
or the Summary for Policymakers. It says (page 439):
Finally, we come to the difficult question of when the detection
and attribution of human-induced climate change is likely to
And it continues:
The body of statistical evidence ... when examined in the
context of our physical understanding of the climate system,
now points towards a discernible human influence on global climate.
Our ability to quantify the magnitude of this effect is currently
limited by uncertainties in key factors, including the magnitude
and patterns of longer-term natural variability and the time-evolving
patterns of forcing by (and response to) greenhouse gases and
After release of the SAR, the man who became the principal
representative of the United States (Clinton/Gore) Administration
at Kyoto, Timothy Wirth, the Under-Secretary of State for Global
Affairs, is reported in a Nature news item on 25 July 1996
(volume 382, page 267) as follows:
Wirth described as a 'remarkable statement' the conclusion
of the IPCC's latest report on climate change, that 'the balance
of evidence suggests that there is a discernible human influence
on global climate'. He said the administration took the report
And, as a reminder of the intellectual climate prevailing in
science at that time (and now):
Wirth described the IPCC's critics as 'naysayers and special
interest groups bent on belittling, attacking and obfuscating
climate change science'.
The 'key finding' of the Preface and Summary for
Policymakers is not justified in the text---but the ploy worked.
This much-publicised claim was the principal motivator for Kyoto.
Contrary to the assertion of the 'Shooting the messenger' editorial,
the scientific findings were not moderated at the time
of political review---they were sharpened. This isn't science
at all, but it is brilliant politics.
After release of the SAR in 1996, a peer-reviewed ex-post
justification of the assertion in IPCC's Preface and Summary
was published (Santer et al. 1996). A numerical model was
used to calculate the warming of the lower atmosphere which should
have resulted from the release of human-caused CO2
from the burning of fossil fuels. The model-calculated warming
was hemispherically-symmetrical, as one might expect, because
the long-lived CO2 emissions (ie,
with an atmospheric residence time of decades to centuries) would
be well-mixed around the globe.
The atmospheric cooling effect of sulphate aerosols---also
emitted from the combustion of fossil fuels---was also calculated.
Because 90% of this cooling aerosol is emitted in the Northern
Hemisphere, and because it has a residence time of only a few
days, the calculated cooling was largely in that same hemisphere.
Hence when the two calculations were combined, it was found
that most of the human-caused net warming was in the Southern
This model-based result was compared with observed temperatures
in the lower atmosphere as recorded by weather balloons. Sure
enough, a warming trend was detected in the Southern Hemisphere---much
as predicted by the model. It was this successful matching of
patterns which became IPCC's 'discernible human influence'.
Surely, this conclusion is spurious! During the 22 years of
comprehensive records from satellites which we have now accumulated,
there is no warming trend for the lower atmosphere of the
Southern Hemisphere---all the observed warming is in the north.
We now know (Michaels and Knappenberger 1996). IPCC relied
on only a short (25-year) run of observed atmospheric temperatures,
encompassing the 1963-87 interval. Indeed, the years selected
do show a warming trend. But that is not the whole story.
Available at the time was a 37-year run of data, including 5 earlier
years back to 1958, and 8 later years up to 1995. When the full
run is used, the warming trend disappears!
IPCC chose a starting year which was cooled by the Mt Agung
eruption, and finished in the warmth of the 1987/88 El Niño.
If it had gone further, it would have been caught by the cooling
associated with the Mt Pinatubo eruption of 1991.
IPCC's warming trend was an artefact of the years chosen for
study; and this dissembling was not well known at the time. It
I would describe the Nature editorial as rather economical
with the truth, or else naive. In this instance, the government
nominees writing the Summary for Policymakers did not
moderate the consensus-based science of IPCC's report. Instead,
they poured petrol on the flames.
4.2 TAR Summary for Policymakers
IPCC's Third Assessment Report 'Climate Change 2001:
the scientific basis' was the scientific underpinning of the Bonn
meeting on 16-23 July.
The principal attention-getter in the TAR is that global
average surface temperature will rise by up to 5.8 ºC by
2100. This startling projection was judged likely to be so efficacious
that it was leaked to the New York Times in the days preceding
the US presidential election. It nearly worked, too!
The Summary for Policymakers of the TAR explains
it this way:
The globally averaged surface temperature is projected to
increase by 1.4 to 5.8 ºC over the period 1990 to 2100.
These results are for the full range of 35 SRES scenarios, based
on a number  of climate models.
A forecast warming of 1.4 ºC is not the stuff which might
win the battle of hearts and minds. But 5.8 ºC is a different
matter indeed. It is the latter figure which is so often quoted---the
highest of IPCC's 35 x 7 = 245 projections. No probability distribution
was attributed by IPCC to its 245 alternative outcomes; I will
return to this topic.
A second point of explanation follows:
Temperature increases are projected to be greater than those
in the SAR, which were about 1.0 to 3.5 ºC based
on the six IS92 scenarios. The higher projected temperatures
and the wider range are due primarily to the lower projected
sulphur dioxide emissions in the SRES scenarios relative to the
If I understand these words correctly, IPCC is saying that
the projected upper bound of warming by 2100 has jumped from 3.5
ºC back in 1996 to a much-more-scary 5.8 ºC now, due
primarily to an expectation of lower (cooling) sulphur dioxide
emissions than previously assumed. This conclusion is crucial
to any judgment of the veracity of IPCC's warming projections.
That I have got it right, is confirmed by a recent exchange
in Nature. A 'concepts' piece entitled 'Room for doubt'
(Pielke 2001), accompanied by a box containing the words 'Consensus
science can only provide an illusion of certainty', doubts the
quality of IPCC's work, at least in a conceptual sense:
... in 1990 ... (IPCC) projected that a doubling of CO2 in the atmosphere would result in a 1.5 to
4.5 ºC mean global temperature change. In 2001, after tens
of billions of dollars of investment in global-change research,
the IPCC now concludes that a doubling of CO2
will result in a 1.5 to 6.0 ºC temperature change. Even
as the IPCC has become more certain that temperature will increase,
the uncertainty associated with its projections has also increased.
IPCC's response was not long delayed. On the next week's correspondence
page was a letter (Stocker 2001) which began:
I read with interest your News article covering the approval
of the Third Assessment Report.... As a coordinating lead author
of one of the chapters, lead author of the technical summary
and a member of the drafting team of the summary for policy-makers,
I would like to clarify [a point].
... although climate modelling has advanced during the past
five years, this is not the main reason for the revised range
of temperature projections. The higher estimates of maximum warming
by the year 2100 stem from a more realistic view of sulphate
aerosol emissions. The new scenarios assume emissions will be
reduced substantially in the coming decades, as this becomes
technically and economically feasible, to avoid acid rain. Sulphate
emissions have a cooling effect, so reducing them leads to higher
estimates of warming.
Here we have it. Clear as a bell!
The increased projections of warming by 2100, as contained
in TAR, are fatally flawed. We know that 90% of the short-lived
cooling aerosol is emitted into the atmosphere of the Northern
Hemisphere, and yet it is the atmosphere of the Southern Hemisphere
which is doing the cooling! The simplest explanation of this surprising
observation is that this aerosol is not presently providing the
cooling which IPCC attributes to it.
Why might this be so? The probable reason is because the burning
of fossil fuels produces both cooling sulphates and warming soot---and
they just about balance. For its extra warming in the century
ahead, IPCC relies on the implausible assumption that those burning
fossil fuels will take the sulphates selectively out of their
stack-gases, while leaving in the soot. How could IPCC's consensus
of 'many hundreds of scientists' let this through?
But in response to this sycophantic Nature editorial,
I want to make a different point. Out of IPCC's 245 cases, only
one forecasts 5.8 ºC warming. Is this forecast very likely,
and hence justification for the prominence it has been given by
IPCC and the media; or has it such a low probability that for
all practical purposes we can ignore it?
The Summary for Policymakers remains silent on this
crucial point. We have been let down by our government-nominated
In my opinion, the highest extreme has a very low probability
indeed. IPCC's 35 SRES scenarios project CO2
concentration in the AD 2100 atmosphere of 490-1260 ppm. These
concentrations are then used in 7 models of varying sensitivity
to produce the 245 outcomes.
IPCC's range of CO2 concentrations can
be compared with a pre-industrial level of about 280 ppm, rising
to 315 ppm when detailed measurements began in 1958. It is now
about 370 ppm; and the growth rate has stabilised at about 1.5
ppm per year---a bit less in cool (volcanic eruption) years, and
a bit more in warm (El Niño) years. The observed increase
was 1.1 ppm in 2000. To get to the high estimate, we would need
an average increase from now on approaching 9 ppm per year!
So much for the consensus of 'many hundreds of scientists'.
Even IPCC's friends are embarrassed. For instance, Wigley and
Raper (2001) say in the abstract to their paper:
The full warming range over 1990 to 2100, 1.4 to 5.8 ºC,
is substantially higher than the range given previously in the
IPCC Second Assessment Report. ... We show that the probabilities
of warming values at both the high and low ends of the TAR
range are very low. In the absence of climate mitigation policies,
the 90% probability interval for 1990 to 2100 warming is 1.7
to 4.9 ºC.
Those who wrote the Summary had an opportunity to introduce
much-needed moderation here---and they didn't take it.
4.3 Can IPCC foretell the future?
Wigley and Raper accept IPCC's models at face value. They are
just trying to make the output intelligible---and hence useful
But neither they nor Nature raise the crucial question.
Even if IPCC correctly predicts the CO2
content of the atmosphere in 2100, can we rely on its forecast
of global climate at that time?
The place to start is with a reconciliation of its models with
known climate-change during the century just past. Yes, on a globally-averaged
basis, hindcasting gives an agreement reasonable enough to quieten
most doubters. But it is a spurious agreement.
Global reconciliation is easy. Over-predicting models can be
made to match an under-warming world on a global basis,
simply by increasing the assumed cooling effect of sulphate aerosol
until they do. But when the hindcasts from IPCC's thus-reconciled
models are examined---with no intervening changes to the input
assumptions, of course---they fail on a regional basis. They show
the Southern, not the Northern, Hemisphere warming the faster.
They have the twentieth-century world the wrong way round.
Also, they show the lower atmosphere warming faster than the
surface. Yet we know from 22 years of satellite coverage, that
the surface is warming on average about three times as fast as
the atmosphere (of which more below).
There is something seriously wrong with IPCC's models; and
until they can match the past, they won't match the future.
In fact the models can't do the job, because they only
work in a uniformitarian world. But the real world has a history
of abrupt nonlinear transitions between climate states---which
the models are unable to replicate.
Two examples of this natural climatic variability are the abrupt
reversal of the previous warming trend in the mid 1940s, and the
abrupt resumption of warming in the late 1970s. Is the jump at
1976/77 (see below) the last such event to be experienced before
2100? Who can say? But I doubt it.
By their silence, those who wrote the Summary for Policymakers
allow us to believe that IPCC can foretell the future. It can't.
Natural variability, often large and often abrupt, remains unpredictable.
5. THE ATMOSPHERE RULES,
In this multi-disciplinary battle for hearts and minds,
Nature is a partisan fighting alongside the atmospheric scientists.
But is it right for a respectable journal to be so focussed? Let's
look at the facts which, the Nature editorial urges us
to believe, are already conclusive enough---but which it doesn't
5.1. A long backward look
The only prolonged periods during the past 300 million years
when the atmospheric CO2 concentration
remained as low as today were way back in the Permian Ice Age,
and over the past few million years leading into the current Ice
About 50 million years before the present, in the warm, wet,
and ice-free paradise of the Eocene optimum, it was 2000-4000
ppm; and by the end of the last Glacial at 15,000 yBP it had declined
to below 200 ppm. At very long time-scales, CO2
concentration in the atmosphere is an obvious driver of global
But during the current Ice Age, the cycle of 90,000 years cold
and 10,000 warm appears to be orbitally driven. The variation
in atmospheric CO2 concentration between
about 180 ppm in the Glacials and 280 ppm in the Interglacials
(such as the present Holocene) is more likely to be effect than
Overprinted on this 100 ky cyclicity is a ca 1500-year
warm/cold cycle of which the Roman Empire warm period, Dark Ages,
Mediaeval Warm Period and Little Ice Age are the latest manifestations
in the North Atlantic Basin. These climatically-disparate periods
are responses to changes in oceanic heat transportation which
appear to be ice-related and inertially-driven.
Overprinted on the shorter 1500-year cyclicity are prominent
climate fluctuations of still-shorter duration. During the Little
Ice Age the (four) colder intervals coincide with periods of reduced
solar activity. The last such cold snap was the Dalton Minimum
at 1800-20. Since then, the world has warmed in three roughly-equal
steps in the early/middle 1800s, from the early 1900s to the mid
40s, and from 1976 to the present day.
For the first two periods of post-LIA warming, in the mid-1800s
and at 1910-45, facts are scarce; but we do know this warming
largely predates the human-caused build-up of CO2
in the atmosphere. There is much circumstantial evidence pointing
to twin drivers (which could even be related in ways we don't
yet recognise)---increased solar magnetic activity, and increased
flow of warm equatorial water into the Nordic seas.
5.2 Newer and stronger evidence
The TAR Summary for Policymakers carries a heading
as follows (but emphasised in bold):
There is newer and stronger evidence that most of the warming
observed over the last 50 years is attributable to human activities.
A reading of the succeeding fine print confirms that we are
talking here of the 'greenhouse effect', and not of urban-heat-island
and land-use-change impacts. Global warming during the twentieth
century was about 0.6 ºC, in two tranches; and in the last
50 years we have an observed surface warming of about 0.3 ºC.
It is this latter warming to which IPCC refers.
Happily, for the last 50 years we have many facts.
The world cooled abruptly in the mid/late 1940s, and temperatures
remained depressed until the third period of post-LIA warming
began abruptly at 1976/77. The most prominent climatic event in
the twentieth century was this step-jump in average global surface
temperature; but you wouldn't know from reading the Summary
for Policymakers of either IPCC's SAR or TAR.
Is the 1976/77 jump a confirmation of IPCC's 'Greenhouse Effect'
hypothesis of global climate change? And is the warming at a lesser
rate since, greenhouse warming?
We all know that greenhouse is a phenomenon of the atmosphere.
If the lower atmosphere doesn't warm, that warmer atmosphere can't
then cause 'greenhouse effect' warming at the surface; greenhouse
gas emissions don't warm the surface directly. No problems here,
From the start of adequate weather balloon coverage at 1958,
right up to the step-jump, both atmosphere and surface cooled
slightly---hardly an indicator of contemporaneous greenhouse warming.
But then, both atmosphere and surface warmed abruptly at 1976/77.
This warming step coincides with a prominent re-ordering of oceanic
circulation, as indicated by a sharp reduction in the upwelling
of cold, deep, water in the eastern Pacific. This is an inertial
event. How do I know? Because of a change in the rate-of-change
of length-of-day at about that time.
It is more plausible that the observed atmospheric warming
at 1976/77 is a response to the contemporaneous oceanic warming,
than vice versa. As corroboration of this line of reasoning,
the prominent cooling in the 1940s coincides with a time
of increased upwelling.
Recently, Hansen et al (2001) have found evidence of
a declining (deep) flow of cold dense water out of the Nordic
seas, and across the Greenland-Scotland sill into the Atlantic,
over the past 50 years. This adds to the (albeit still limited,
but growing) evidence that the main climatic driver over the past
half-century is much more likely to be changes in oceanic heat
transportation than changes in atmospheric composition: Oceans
one; Atmosphere nil.
5.3 The past two decades
But what of the continued warming since 1977? There is even
more information available for the past two decades. In particular,
we have the coverage of satellite-derived atmospheric temperatures
since 1979. During this time (now 221/2
years, and counting), the atmosphere has warmed only a third as
fast as the surface. The simplest explanation for the discrepancy
is that most of the surface warming during this time is not greenhouse
Looking now in more detail, there is no warming of the lower
atmosphere in the Southern Hemisphere. This is unsurprising. The
dominant greenhouse gas is (naturally-occurring) water vapour,
and it will tend to mask the potential warming impact of lesser
GHGs such as anthropogenic CO2. Where does
water vapour come from? It comes from evaporation; and the surface
of this hemisphere is 80% water.
The only observed atmospheric warming trend over the period
is in the mid latitudes of the Northern Hemisphere. Here, the
crucial clue is that most of the observed warming is over land,
and in winter.
It is the intensely-cold, bone-dry, anti-cyclonic cells, which
tarry over Siberia and Alaska/Yukon in winter, which enjoy most
of the warming---although surface temperatures beneath them still
remain far below freezing (and hence, their environmental impact
This could well be greenhouse warming: Oceans 11/2; Atmosphere 1/2.
5.4 Looking ahead
Predicting future climate is still beyond us. But there are
some things we do know.
We cannot stabilise global climate by 'doing the right
thing' about greenhouse gas emissions. But by pretending that
the impossible is possible, we are already diverting much-needed
effort from environmental threats, some irreversible, on which
we can have an impact.
Natural climate variability will always be; and so will extreme
climatic events. Greenhouse effect or not, prompt mitigation of
weather-related human suffering will remain a need.
We are in the latter days of our 'normal' allowance of 10,000
years of benign climate. Already, summer insolation at higher
latitudes of the Northern Hemisphere is on the wane. Will the
next 'Little Ice Age' be the one which pushes Earth beyond the
point of no return---from whence cooling feedbacks lead inexorably
to the impending Glacial? When it comes, Armageddon will be cold,
Twenty thousand years ago, fortunate Australians walked through
the dunes of Bass Strait to Tasmania. In not-so-fortunate America
then, a kilometre of ice covered the site of Detroit. How soon
will it be before we are welcoming US Boat People to our shores?
6. HELLO THERE, NATURE!
- How can you justify limiting the scientific consideration
of climate change to atmospheric scientists only?
- Why do non-atmospheric scientists who question IPCC's autistic
fixation with the atmosphere make you think of Aids or tobacco?
- Why is reasoned dissent, from IPCC's advocacy of decarbonising
the western world, immoral?
- You support the advancement of science, but you object to
scientific debate having two sides.
- Finally, you paint scientific consensus as a virtue. But
no amount of consensus-building can make IPCC's scientists
'right'. The advancement of science is not a matter of voting;
and we know that if it were, science would never advance.
Hansen, Bogi, William R. Turrell and Svein Østerhus
2001, 'Decreasing overflow from the Nordic seas into the Atlantic
Ocean through the Faroe Bank channel since 1950', Nature
volume 411, pages 927-30.
Michaels, P.J. and P.C. Knappenberger 1996, 'Human effect on
global climate?', Nature volume 384, pages 522-3.
Pielke, Roger A. Jr 2001, 'Room for doubt', Nature volume
410, page 151.
Santer, B.D. et al 1996, 'A search for human influences
on the thermal structure of the atmosphere', Nature volume
382, pages 39-46.
Stocker, Thomas 2001, 'Climate panel looked at all the evidence',
Nature volume 410, page 299.
Wigley, T.M.L. and S.C.B. Raper 2001, 'Interpretation of high
projections for global-mean warming', Science volume 293,