Examination of Witnesses (Questions 80
WEDNESDAY 13 DECEMBER 2000
80. Dr Shackley made a point about the international
dimension in this. There are forces out there, Saudi Arabia, Kuwait,
President Bush or dissenters in the United States that are looking
for your kind of point of view.
(Professor Bowen) The best forum that exists right
now is the American Geophysical Union in San Francisco but yet
again I do not think it meets all the criteria that everyone is
there talking with everybody else. There was a PPARC/NERC meeting
in London last month looking at the sun climate links and there
were just three non-solar physicists there out of 75 people. It
seems to me that a conscious effort has to be put into this to
obtain all shades of opinion on the definitive facts that different
groups of people can produce.
81. Professor O'Neill, you are involved as well
in IPCC work. What is the consensus among scientists? Is it 80
or 90 per cent likely that it is carbon dioxide and methane and
these greenhouse gases and not these sun spots or whatever?
(Professor O'Neill) The relationship of solar variability
to climate is a very challenging issue and we do not know all
the answers. We know the solar connection with climate change
must be important because we have had ice ages and periods in
between ice ages. What is more controversial is the extent to
which solar variability on a timescale of 100 or so years, which
is very pertinent to us now where we are seeing changes in the
temperature recordthat is much more controversial. Broadly
speaking, 90 per centprobably moreof scientists
involved in climate research in terms of what is happening now
and what could happen in the future will be of the opinion that
it is associated with greenhouse gases, but the effect of the
solar variabilityand there is a contribution, albeit uncertainis
of rather lesser magnitude on that timescale.
82. Professor Bowen, you disagree?
(Professor Bowen) I do not believe science works by
consensus. The only consensus in this business is that one computer
model replicates more or less what the other computer model shows.
Sir Paddy Ashdown
83. Precisely on that, let me see if I can tempt
Professor Bowen to a rather more brutal statement. Is it your
view that the closeness of the relationship with the Hadley Centre
is leading to the danger of the fact that the Government is caught
in something of a fad here which is self-reinforcing or, at the
very least, is insufficiently challenged by dissenting views and
other scientific disciplines?
(Professor Bowen) I really would like some notice
on such a question but perhaps by saying that you have my answer!
Sir Paddy Ashdown: I will presume yes!
84. What would you do about it? You talk about
the need for all the different disciplines to get together. Is
not the IPCC the appropriate forum for that? Have you any suggestions
as to how we improve the way that functions? What has the IPCC
achieved? What do you think of the way it functions? How could
it be improved?
(Professor Bowen) I think the IPCC in their publications
have done an absolutely marvellous job of describing the climate
system in its various aspects, quite magnificent. Where I am less
happy and would like to see a larger range of people involved
would be in some of the details that would not necessarily strengthen
the position of the statement that says that greenhouse gases
are causing climate change and will cause a major climate change
in the future. There are distinguished scientists around the world
who will say very clearly that we simply do not know and if we
pretend that we do know that is the worst possible thing we could
(Professor O'Neill) I do not think we pretend we know.
We recognise that there are uncertainties and chains of uncertainties.
The international effort has been very much geared up to narrowing
those uncertainties and removing them. I am not aware of any sense
of international conspiracy because the best way for scientists
to make a reputation is to break the mould and I would not hesitate
to do that if I could. It is always possible to have a dissenting
voice and one would encourage it. What we have to do is take the
dissenting voice, see what it is based on scientifically and test
out the science. That is the acid test in the end, to see whether
we can explain what we see by the mechanism that is being used
or by the hypothesis that is being used. I agree with Professor
Bowen: I think the IPCC has done a magnificent job. It is realising
more and more the importance of the role of uncertainties. I do
not think people in IPCC feel that the uncertainty is going to
turn around dramatically the basic tenor of the advice that has
been given. One has to feel much more comfortable about the nature
of the advice when some of the significant uncertainties in various
parts of the system have narrowed down.
(Dr Shackley) We have to distinguish between different
disciplines in terms of how they contribute to science and climate
change. There is a group of scientists who make predictions or
scenarios of future climate change using models and then there
are other people who, say, do studies of historical climate change,
but those people doing historical studies are not the people who
are making predictions of future change. They might provide material
that can be used to validate the models that are used for predictions,
but a lot of these other communities who have not been so centrally
involved are not actually the communities who are making the key
claims in the science about the future change, which is after
all what really matters in policy terms. That probably explains
why there is this different arrangement of disciplines and why
some have not been so involved. Amongst the scientists who are
making predictions there is, as well as a common understanding
of the science, also an element of a precautionary ethic in the
work of, say, the IPCC in the sense that there are some values
in there that we should be erring on the side of caution when
it comes to issues like climate change. I would not try and pretend
that this is purely driven by science. I think it is also partly
driven by an emerging set of values about protecting the global
85. Does it really matter? Irrespective of whether
the models and predictions are accurate, based on the precautionary
approach, should we not actually be doing absolutely everything
we can to reduce greenhouse gases and other forms of pollution?
Would the other members wish to comment on Dr Shackley's comments
and that further question?
(Professor Bowen) Absolutely. I think we are doing
that, are we not? If you look at the record of lead, for example,
in Greenland ice cores since unleaded petrol has been used it
has actually plummeted. If we pay attention to methane and we
pay attention to aerosols in the atmosphere, I think we are paying
attention to the precautionary principle but how far do you take
it? How far do you take it on coastlines? How far do you take
it, if you can take it any further, on flood plains? How far do
you take it in certain circumstances when it is going to take
a great deal of the gross national product? I hesitate to introduce
a moral point at this stage but at a time when most of the world's
people are living in absolute destitution might the money not
be better spent in raising their standard of living?
86. Which money is this? The money that is being
spent on what?
(Professor Bowen) The money that is being spent to
a large extent on negating perceived aspects of climate change,
various defence schemes.
87. What about changed behaviour? All the research
is used by Government to develop their policy and obviously the
issue is how far governments should go to restrict CO2
emissions and so on which could result in considerable changes
in lifestyle, which could have financially beneficial effects,
not just cost money.
(Professor Bowen) This is a political matter. It is
really up to what the voter can take in such situations.
88. They want a prop, if you like, in taking
those difficult political decisions.
(Professor Bowen) I think the things we are talking
about are so esoteric as far as the public are concerned that
they are either unable or unwilling to evaluate them and it seems
to me therefore that you would never convince the public to stump
up their pound in their own pockets in this quest.
89. The British public, the German public, the
European public, has accepted Kyoto, have accepted carbon dioxide,
have accepted global warming and are very environment sensitive.
The American public is not but perhaps their politicians are.
Could we just talk about unleaded petrol? The great thing about
unleaded petrol, or the problem of lead pollution, was that there
was a technical solution, a ready economic one, but in this case
it is much more intractable. I challenge your pessimism about
the understanding and the desire of the European public to have
(Professor Bowen) I did not come here to talk about
Kyoto; I came here to talk about climate systems.
90. I want to make sure that we have got all
the uncertainties on the table. I have written downwhile
we have been talking uncertainties, about the modelling experiments
which after all are experiments, and there must be various models
being explored there, so that is one possible uncertainty - I
have written down the question: have we taken solar sources into
account adequately, and I have put a question mark on greenhouse
gas emissions? Are we, for example, taking into account all the
forest fires that there are in a year, for example? I read a statement
recently that all the forest fires in a year put out more dioxins
in one year than man has ever put out synthetically himself or
herself. Are we not tinkering at the edges with carbon dioxide
when we look at the forest fires that occurred last year? Are
we taking that uncertainty into account? There are three uncertainties.
Could you give us any more uncertainties that we should be considering
in this debate?
(Professor Bowen) If you would like a paradigm of
uncertainties, I think we are currently aware of a whole variety
of forcing functions as far as the climate is concerned, some
of them acting at different cycles. These are the pacemakers,
and very often we can see the end product of these forcing functions,
but in between there is a great black box. We see the forcing
going in and what comes out very often amplifies the forcing that
has gone in, so there are powerful non-linear feedbacks operating
within the system. These are uncertainties that fall into the
realm of the unknowability at the present time and will remain
in that realm of unknowability for a long time. It is frequently
said, for example, that we know what caused the ice ages. We do
not know what caused the ice ages. We know that the forcing function
is the pacemaker to orbital changes of the earth around the sun
and we know what the output is. It is the geological record of
ice ages, but the record of ice ages doubles the input that goes
into that system. We simply do not know how the atmosphere, the
cryosphere, the world of ice and snow, the greenhouse gas system,
the ocean circulation, work; we do not have an adequate handle
on these. It is only through increased high quality data and modelling
of that data that we shall ever get to that position.
91. Do either of your colleagues want to add
(Professor O'Neill) It is an interesting question
about whether or not we have an adequate knowledge. I would certainly
agree with you that there remain uncertainties in every corner
we look at. In terms of what is likely to be the outcome of pumping
greenhouse gases into the atmosphere for the next 50 to 100 years
I am less pessimistic in the sense that we do not have an adequate
knowledge of all these factors. I would add a few areas of uncertainty.
We are going to witness one evolution of the planet in the next
50 years. If we were to set up lots of different worlds under
pretty similar conditions each of these world would evolve slightly
differently, so we would get natural variability. It could well
be for examplelet me be specificthat in the next
30 years we will see a decline in temperature. That would not
in any shape or form rule out the underlying notion that there
is a longer term trend in the temperature record because we have
got superimposed on the forcing of the greenhouse gases natural
variability in the system. That is one area of uncertainty. Another
area of uncertainty I would say is the response of the biosphere
to changing climate. There are very significant sources of things
like carbon which are quite natural and you have mentioned that
point already. As climate changes vegetation will inevitably change.
We are talking about changes in quite rapid timescales again.
It could well be, and some calculations suggest, that changes
in the natural carbon cycle may exacerbate what man is doing in
that area. I would caution that there are lots of uncertainties
in that one. Possibly one of the biggest uncertainties is how
human beings themselves will respond. This is ultimately the fulcrum
process. We are part of the natural system in some respects, and
how we respond to what we see happening, what the predictions
will be and how the nations of the world get together or do not
is going to be a major area of uncertainty for climate modelling.
(Dr Shackley) The uncertainty I see in a sense is
the bread and butter of what scientists do and scientists love
talking about uncertainty and can sometimes give the impression
that that is all there is. What is actually quite remarkable about
the climate change is the degree of certainty that has been formed
internationally through the IPCC, through a very rigorous process
of review. Scientists will always find uncertainties, but if you
push them and say, "Do you really think that greenhouse gas
emissions will cause global temperatures to increase within a
range of 1.5 to 4.5ºC for the doubling of CO2?",
then the vast majority of those scientists will say that they
do believe that. At a certain point when this uncertainty is not
affecting their basic judgment the science of climate change is
rather sound and is quite well understood.
92. Do you feel that the policy makers that
you advise, and other scientists advise, are capable of understanding
all the uncertainties in the argument, or do you find that they
are putting pressure on you to provide black and white answers
to their questions?
(Dr Shackley) I think the policy system does tend
to prefer certainty and finds uncertainty difficult to deal with.
That is often because the amount of time you have to invest to
understand the significance about uncertainty is rather high and
most policy makers simply do not have the time so they prefer
the story to be told without excessive mention of uncertainty
and relying on scientists' judgment. That is where the IPCC has
been very useful because it has provided an international forum
where the world's best scientists can actually have this discussion
and they are all coming from their own particular viewpoints,
their own organisations, but additionally it is including governmental
representatives, representatives of industry and representatives
of environmental groups, so you have got all these different perspectives
that have to be taken account of in how that knowledge is distilled
and then presented without excessive mention of uncertainty. It
is rather an interesting process by which this distillation does
not just involve scientists and its strength is that it is being
reviewed by the wider community.
93. I might throw a naughty question in here
which is not on the sheet, and that is: why does not the American
Government listen to its scientists?
(Professor Bowen) Who says they do not? I think a
great deal of advice does go to the American Government and this
is quite independent of the so-called industrial interests that
are supposedly financing some of the people. I think the quality
of advice that goes to the Government from NASA, for example,
from the NSF, from various high powered institutions like the
Lawrence Livermore Lab, Berkeley, California, is very high and
I think that the calibre of many congressmen in scientific terms
is also quite high.
Dr Turner: We have met one of them that possibly
was not, but perhaps that is colouring the question.
Dr Jones: The member of the committee that we
met when we were in the States a couple of years ago completely
and utterly denied that climate change was happening.
94. What you are saying is that the advice is
there, obviously the Government is listening, but the industrial
lobby is preventing them from taking any action?
(Professor Bowen) No, I am not saying that at all.
I do not know if my colleagues would agree with me.
95. I am sorry if I misrepresented you.
(Professor Bowen) In terms of manpower resources that
are devoted to this issue the United States far eclipses what
is being invested in the British Isles. Most of the front line
action is taking place there, not in this country. France is slowly
catching up but it is the US. It is a massive effort.
96. But is it a massive effort in these negative
areas that you are involved in rather than the modelling and so
(Professor Bowen) No. I think you will find at least
50 per cent of the scientists who write the IPCC reports take
the position that there will be enhanced global warming in the
future. I do not think that is the case at all.
97. Taking up what Dr Shackley was saying, do
you consider that the IPCC as a process is a good model for scientific
advice to government in other areas? Is there not a danger that
they are too consensual? Peer review was mentioned. How satisfied
are you that those invited to participate in peer review are sufficiently
(Dr Shackley) I think it is a good model for some
issues. Obviously, it arose because it is a global issue. We are
talking about systems that are connected globally so to do any
science or assessment you have to start from the global level.
There are many other issues you do not have to start at the global
level. You can start at the local level and work in a range of
scales. I do not think automatically it would work for political
reasons for certain issues but when you are talking about
98. One issue you suggested was genetically
modified organisms, for example.
(Dr Shackley) I have not thought that through but
I can see the value of some sort of international assessment.
You have to recognise that the climate change work builds upon
at least three decades of dedicated scientific effort. As Professor
Bowen says, the US has put huge amounts of resource and in a sense
allowed the capacity to be there for the process. I am not sure
if in GMOs that is the case. On your point about diversity, I
have been to IPCC meetings where what typically happens is that
the industrial lobby of the United States will be looking for
any signs of weakness in the science and any uncertainties which
it can use to try and reduce or weaken the argument. They will
send somebody over to the Kuwait and Saudi Arabia delegation in
order to get the question asked within the plenary. This is quite
an effective mechanism by which any uncertainties or questions
of credibility of the science are seized upon and communicated
rather quickly to the political faction which might find this
helpful. That is a legitimate process within the IPCC and they
live with that. They have to have it out in discussion, which
is why their meetings tend to last until the early hours.
99. Professor O'Neill, I would like to ask you
about the Hadley Centre climate modelling. It has a lot of mathematicians
and physicists and an international reputation for its work, but
does it have enough biologists and other social scientists?
(Professor O'Neill) No. That is an area that I believe
the Hadley Centre recognises increasingly, although I would not
want to speak for them: the importance of those disciplines in
getting the full picture of how climate is likely to change. They
are moving slowly in that direction. There is a large community
of extremely capable biologists who have relevant knowledge in
the United Kingdom and in Europe. If I was in the position of
encouraging them, I would encourage them to tap into that knowledge