Examination of Witnesses (Questions 63
WEDNESDAY 13 DECEMBER 2000
63. Good afternoon and welcome, Professor Bowen,
Professor O'Neill and Dr Shackley. This Committee's inquiry, as
you know, is concerned with the field of scientific advice to
Government. This Committee is not trying to resolve all the outstanding
questions on climate change, causes, models, etc. None the less
we are concerned with the quality of advice on those issues which
goes to Government and Government's response to that advice. That
is the context in which this inquiry is set. Could I begin, gentlemen,
by asking you each to introduce yourselves and explain briefly
how you are involved in the study of climate change. Can you mention
in passing whether any of you work with the Hadley Centre or the
IPCC and have any of you contributed to the peer review process
which precedes the publication of IPCC reports? Incidentally,
given that you do not necessarily all come from the same viewpoint,
it is probably best if we make the questions fairly general unless
someone wants to ask any one of you individually, so that you
all feel free to contribute.
(Professor O'Neill) I am Alan O'Neill. I am the Director
of the Centre for Global Atmospheric Modelling at the University
of Reading. My involvement in climate research is that I am a
climate modeller, I use complex models of the climate system to
check out the models, how they perform, how they behave. I am
not involved in the longer term predictions associated with increasing
greenhouse gases. I used to work for the Hadley Centre; I no longer
do that. I have not been involved in the peer review process for
(Professor Bowen) I am David Bowen. I am Professor
of Quaternary Geology in Cardiff University. My research interest
over the last nearly 40 years has been with changes in the climate
system on long timescales, glacials and interglacials, but recently
I have been looking at changes on millennial timescales; hence
my interest in giving evidence today. I have nature conservation
interests. I was a member of the Nature Conservancy Council, I
was a founder member of the Joint Nature Conservation Committee,
and I have been Deputy Chairman of the Countryside Council for
Wales for the last ten years. I have no connection with IPCC.
I have no connection with the Hadley Centre and no connection
with the peer review process. I am totally independent.
(Dr Shackley) I am a social scientist and I work at
UMIST. I am also one of the research programme managers of the
new National Tyndall Centre for Climate Change Research within
the new national centre. My involvement in this is that I have
studied the process by which Government gets and assesses scientific
advice on climate change through working at the Hadley Centre
for a few months and talking to a lot of scientists and policy
makers involved in this both within the United Kingdom and internationally.
I have attended a number of IPCC meetings, not to be a scientist
assessing the reports but to look at how the scientists themselves
go about the assessment process and to look at how we can assess
how rigorous that process is.
64. Can I ask you, in turn, to state whether
you think your views on climate change accord with the general
tenor of the IPCC reports, or do you hold dissenting views?
(Professor O'Neill) I generally accord with the IPCC
reports. I recognise that there are uncertainties in climate predictions
but nevertheless I subscribe to the weight of evidence that has
been advanced in IPCC.
(Professor Bowen) I would rather place more emphasis
on uncertainty in the climate system. I would certainly like to
see them take into consideration what is now definitively known
about how the climate system changed in the past. In the 1996
report, for example, only three per cent of that report was devoted
to past changes in climate.
(Dr Shackley) I think there is a difference between
the policy makers' summary of the IPCC and the full report and
within the full report there is a whole wealth of viewpoints and
uncertainties that do not always find themselves in the policy
makers' summary. In terms of the full report I think that does
represent the broad range of opinion within the community.
65. Again, I have to ask you each individually:
have you ever been asked for advice on climate change by the Government?
How was your advice treated if it was sought? Conversely, have
you ever offered the Government advice and, if so, how was that
(Professor O'Neill) I have been involved in giving
Government advice on an issue related mostly to climate change
or global change, and that was on ozone depletion, and a panel
was created, the Stratospheric Ozone Review Group, which gave
advice to Government through DETR. That advice was well received
and evidently played a part in the Government's position vis-a-vis
phasing out the chemicals that damage the ozone layer. I have
not offered unsolicited advice to the Government.
(Professor Bowen) Only through the agencies of non-governmental
departmental bodies such as NCC and JNCC and latterly the Countryside
Council for Wales. My advice on all of these occasions has been
much the same, simply to state the level of uncertainty, not to
take precipitate action without good cause, to understand that
flood plains flood and coastal plains flood.
(Dr Shackley) As a social scientist I have not been
asked for advice on natural science. In terms of the social science
aspects of climate change these are increasingly important issues.
The Government's advisory system is less well developed than it
is in the natural science area that the Hadley Centre provides
and I think there is a need for better channels and different
sorts of channels than they have established in the natural science
66. Professor O'Neill, I want to explore the
mathematical modelling of climate change models and you seem to
be the expert on this from what you have just said to us. How
good are these mathematical models and what are the limitations
of these models? Do we have a grid big enough to predict this,
given that there are so many variables and these are dynamic variables,
patently? I wonder if you could tell us the limits and the uncertainties
in your mathematical modelling work.
(Professor O'Neill) This is a long story and I will
have to keep it brief. The system we are dealing with is a highly
complex coupled system as we say, so there are many interacting
components: atmosphere, ocean, land, biosphere. In the last 30
years or so we have made very considerable advances in the development
of the climate models to represent basic climate variability.
That has been aided by the enhancement of computer technology
and also by the availability of comprehensive satellite data which
we can test our models against. A nutshell statement would be
that the models now show very good abilities in predicting basic
elements of the variability of the climate system. However, we
recognise also that there are limitations in models. We know to
a good approximation the physical laws that govern many of the
important processes but when we try to solve those laws we cannot
do it by hand; we have to use a computer, which means that we
have to approximate the equations. Because the system is so complexit
involves a range of time and space scaleswe inevitably
make approximations in that representation on the grid. That is
part of the reason we have uncertainties in the system. For example,
a comparable case would be how do we represent properly clouds
in a climate system? That is pretty obvious, that clouds would
be quite important in deciding how the climate is going to behave.
In summaryand you can press me further on the detailis
that one bears in mind two things, that the climate models that
we are using are based on basic physical laws that are tested
day after day in weather forecasting. They are also evaluated
on longer timescales against global data and there is a great
community of people out there who do that job. There are some
weaknesses in the models. I have alluded to clouds already. We
also have to represent more accurately than we do the role of
the oceans. There are considerable uncertainties remaining in
the way land surface processes, ocean processes, biological processes,
impact on climate change. There is a feedback which we need to
67. That tells me how you have set up the equation
and the difficulties of it but how good are your models in predicting?
Do you get it right seven out of ten times, or nine out of ten
times, or do you get it right absolutely?
(Professor O'Neill) When we say do we get it right,
we have to think about how we evaluate the models. We are dealing
with a system which in many respects has chaotic elements embedded
in elements that are more predictable. When we test out our models
we are looking at past data and we see to what extent the models
capture the basic processes, the evolution, the differences, say,
in one hemisphere from another. We are looking very closely at
phenomena such as the Indian monsoon, the El Niño, phenomena
like that, and those are the ways in which we evaluate our models.
When it comes to forecasting we have to take into account that
there is inherent uncertainty and unpredictability in the system,
or some elements of it, and therefore evaluating the model is
a bit of a tricky process because if the model does not exactly
perform compared with, say, how the atmosphere evolves in a particular
time, it does not mean the model is wrong. That can be just to
do with the system being so complex with some unpredictable elements.
That is not the same when it comes to global climate change, that
is to say, the climate change brought about by man's emissions
from the burning of fossil fuels. That is not to say that the
models then are not capable of being used for that purpose. In
fact, quite recently they have been tested quite carefully against
the recent temperature record when one puts into the models the
greenhouse gases, changes in solar variability, aerosols, and
compared to the global temperature, and a very considerable degree
of success has been achieved in doing that. It is a matter of
timescales and also of exactly what you are looking at.
68. Professor Bowen, do you have any observations
about that? I am looking at this piece of evidence that you have
supplied us with, showing that we have only this year reached
temperatures of the Neolithic period.
(Professor Bowen) Not quite.
69. We seem to have got there in the late summer
or early autumn which was the peak, and showed variations in solar
radiation which have similar patterns.
(Professor Bowen) First of all I could say that anybody
studying natural systems must at the end of the day seek to model
their systems and model them mathematically. The existing climate
models have improved enormously over the last five years but they
are still deficient in the sense that a model cannot incorporate
all aspects of reality. My colleague just referred to the lack
of cloud data. I do not think we are going to have this cloud
data for another three years when CLOUDSAT goes up. This will
be a satellite sent up specifically for reporting cloud cover
characteristics, something we have not had before, although some
of the NASA satellites that went up in the late seventies had
radiometers on board and did produce a certain amount of information.
As far as that diagram is concerned, yes, the temperature reconstruction
is very close to IPCC. It is Jim Hansen's reconstruction and Jim
Hansen is the man who coined the term "global warming"
when he addressed Congress in 1987, and it shows very clearly
the band of climate variability that was enjoyed (in so far as
we can determine that from fossil evidence) during the Neolithic
period about 6,000 years ago, and also during the last interglacial
125,000 years ago. The current climate has not reached that band
of variability yet, yet the boundary conditions, the seaways,
the ocean passages, the mountain systems, are much the same now
as they were 125,000 years ago. If one is looking for a perfect
analogue for the earth in recent geological time one needs to
go back to 400,000 years, and that is the time when the orbital
parameters of the earth were the same as they are today, and that
interglacial was warmer than at present. It was natural warmth.
The sea level was higher. Towards the end of the interglacial
the sea level was ten metres above present, but the difference
between this interglacial and that interglacial is that, whereas
this has only been running 11,500 years, that lasted 60,000 years
and I suspect that the longer this interglacial lasts the higher
sea level will dribble up naturally, quite apart from any human
forces that will be added to that, and that is the realm of uncertainty.
70. I want to follow on, Dr Shackley, if you
can comment as policy maker to ask how well can people in your
field appreciate the limits of mathematical modelling? Do they
appreciate that there are limits which are highlighted by Professor
Bowen and how do you view it?
(Dr Shackley) It is an interesting question because
one of the problems in the past has been that people using data
from climate models perceived that it was more certain than it
actually is when you are doing, say, studies of the impacts of
climate change on, say, flooding or upon agriculture. I think
there has been quite a lot of learning that has now happened by
those scientists talking to the climate modellers and there is
better understanding now that these are scenarios, they are not
predictions. There is a wide range of possibilities because of
uncertainty, not only in the science but also uncertainty in how
much future emissions of greenhouse gases will be, which is determined
by essentially economic and policy decisions.
71. Do you think in the past that policy makers
relied too much on mathematical modelling in assessing climate
(Dr Shackley) There is always a temptation to resort
to a mathematical model because it appears to be something very
objective, very rigorous, but the evidence we have heard already
suggests that validating these models is very complex. We can
probably never validate them to 100 per cent. There is always
going to be residual uncertainty. One consequence of that is that
we need to support a plurality of methods in looking at issues
like climate change. We should not just put our trust in one particular
method. Because of the uncertainty, we should perhaps foster a
number of competing ways of looking at the same issue, if they
are of good enough scientific quality.
72. What are they?
(Dr Shackley) There is a range of different kinds
of climate models that can be used to assess climate change. The
large, complex, coupled models are only one of a family of models.
You could make the argument that we have put all the research
money into supporting the big, complex models, whereas we could
have been supporting for far less money some of the simpler models
that could provide equally useful outputs for answering particular
73. Given that practically the only response
the Government has to climate change is to try and reduce CO2
output, given that Professor Bowen has eloquently explained how
climate change is happening without any human activity, would
anyone like to comment on the effectiveness of Kyoto targets in
making any actual impact on climate change, even assuming that
we manage to achieve them?
(Professor O'Neill) Certainly it is the case that
climate has changed greatly in the past quite naturally, before
man walked the surface of the earth. There is no question about
that. We see that in a number of records. What we are facing now
is rapidity of climate change. The evidence is that that rapid
climate change on a timescale of 100 years has been brought about
by increases in the loading of greenhouse gases in the atmosphere.
What we know also is that, even if we take considerable measures
to cut or reduce the amount of greenhouse gas that we are emitting
over the next 20/25 years, it takes such a long time for the gases
to be expunged from the atmosphere or to be reduced to their natural
levels that we are going to be committed to a measure of climate
change increased by the increase in greenhouse gases. I can give
you a whole host of scenarios with different outcomes according
to the mathematical models, but the longer we delay the process
the more we are committed to longer term climate change, if the
mathematical models are to be believed, which I believe they are
in this context.
(Professor Bowen) My feeling is that Kyoto has now
passed. If I may refer to Jim Hansen, he published a paper in
August. There has been a supplementary open letter and quoting
the CO2 forcing for 2050, a forcing of about three
watts per square metre is involved. He has suggested that that
could be cut down to one watt per square metre if carbon dioxide
is kept more or less at the present levels and we attack the other
greenhouse gases, methane in particular. The rate of methane increase
has been decreasing in recent years and in particular if we attack
particulate matter, exhaust fumes and, coming from India above
all places, particulate soot matterit has formed a deep,
optical layer over the Indian Ocean that is influencing the greenhouse
effectthat is one possible solution out of it.
(Dr Shackley) This is partly an issue of timescale.
What Jim Hansen says might be true for 2050 but the continuing
emission of carbon will eventually result in a much higher rate
of global warming. I think it is only valid on a relatively short
timescale. On Kyoto, the key thing is that the 5.2 per cent reduction
in greenhouse gas emissions from industrialised countries makes
a very insignificant effect upon the climate, but it is only a
first step and the Kyoto protocol was always only ever seen as
being a first step in a long term process of cutting emissions
far more than 5.2 per cent.
Dr Turner: The US has not even ratified that.
74. Dr Shackley, you are an expert on scientific
advice to government. On climate change, where is the Government
getting most of its advice?
(Dr Shackley) It is undeniably from the Hadley Centre.
75. Is that 50 per cent, 80 per cent or 90 per
(Dr Shackley) I would say 90 per cent. Within the
Hadley Centre there is a very strong connection with the IPCC
process. The Hadley provides access to the government to a much
wider range of international scientists. Also, Hadley places contracts
with a number of other university departments around the United
Kingdom. Again, it is not just Hadley; it also extends to a much
76. The Hadley Centre is completely funded by
government, is it not?
(Dr Shackley) I believe it is.
77. I noticed in your submission to us you said
that there is a close and cooperative relationship between officials
at the Hadley Centre and those in relevant government departments.
"We have evidence that frequent face-to-face and remote communications
between government officials and Hadley Centre scientists has
many benefits for the interpretation of scientific understanding
and new knowledge. This kind of relationship between climate scientists
and government officials is rarely found elsewhere in the world
...". There are very close relations between government and
this particular scientific advisory committee. Most advisory committees
take pride in their independence from government; yet here you
are saying that, because this works so closely with the government,
the government listens much more to its advice.
(Dr Shackley) Perhaps one of the important differences
is because you have the assessment of the intergovernmental panel
on climate change, which is entirely separate from government.
It is intergovernmental but there are so many different parties
involved that no one party can influence it very much. That provides
the sort of reassurance that this assessment is independent of
any particular government or any particular scientific organisation.
It is probably because it is connected to this international process
that this close relationship functions rather well. If it was
purely a national assessment, it could very easily go wrong in
the way that you imply.
78. This kind of close relationship could work
here but in the case of BSE or GM foods, nuclear power or some
other controversial issue, where there is international back-up,
there will be big changes needed.
(Dr Shackley) Yes.
79. Where Professor Bowen and other people have
dissident views, do you feel that the mechanisms we have are so
heavily dependent on Hadley that people have slightly different
views, as happened with BSE, or is it the case, as with GM foods,
they are out there doing their own thing, getting published but
not getting noticed or considered by government?
(Professor Bowen) Yes. I do not believe people talk
enough to each other. Different groups of different persuasions
simply do not get together. For example, ideally you should have
a solar physicist here today who would have told you that the
climate models underestimate the amount of solar forcing by a
factor of three. A moment ago I talked about watts per square
metre. It does not mean much to people but three watts per metre
squared is three Christmas tree light bulbs put on every square
metre of the earth's surface; yet we now know that solar radiance
has increased by 2.8 watts per square metre from the Little Ice
Age to the present. Given my own particular persuasion, it seems
to me that we simply do not talk to people. We should be talking
to oceanographers and modellers.