Examination of Witness (Questions 1 -
19)
WEDNESDAY 15 MARCH 2000
SIR JOHN
HOUGHTON CBE
Chairman
1. Sir John, welcome to the Science and Technology
Committee, and not for the first time. You appeared before this
Committee in the last Parliament, although I have only been its
Chairman since the last election. You last came to this Committee
in 1996 to give evidence on climate change, but I also remember
you appearing before the old Energy Committee which I chaired,
and you may recall that. So we have worked out that the world
is cycical and so are your appearances before Select Committees.
We are not looking into global warming, as such, we are doing
a major report into scientific advice to Government, which seeks
clarification of the ways in which scientific advice is used and
the purposes of that use, so we are taking as granted there is
climate change. This is to be the fourth of our four chapters
of this report, and we have been publishing them as we complete
each one. The first looked at scientific advice relating to genetically-modified
foods, the second at that relating to mobile 'phones. The third
was on diabetes and driving. And this will be the last. Sir John,
would you please say a few words about yourself and your involvement
in climate change, as briefly as you think is appropriate?
(Sir John Houghton) Most of my time at the moment
is taken up with the Intergovernmental Panel on Climate Change,
with the Scientific Assessment Working Group of that panel. I
was Chief Executive of the Meteorological Office from 1983 to
1988.
2. Thank you very much indeed. Could you just
give us a brief overview of the IPCC and Working Group I which
you Co-Chair?
(Sir John Houghton) Yes. We were founded in 1988 jointly
by the World Meteorological Organisation and the United Nations
Environment Programme. Our main task is to produce comprehensive
assessments of human-induced climate change to try to make them
as authoritative as we can, to involve the world scientific communities,
so far as we are able to do that, and to produce documents that
are therefore very useful to scientists and politicians and industrialists
and, in fact, the general public around the world. We have produced
reports in 1990, the very first one was in 1990, the second comprehensive
report was in 1995, though in the meantime, between 1991 and 1995,
as Working Group I, we produced two interim reports, in 1992 and
1994, on specific topics. And then we are preparing a new one
now, a new comprehensive report for next year, 2001, which is
more complicated, and it will be longer, I am afraid, it involves
more people, it involves more disciplines, but it will be of the
same kind as we produced before. The other report we produced
recently, as Working Group I, jointly with Working Group III,
was the report on Climate Change and Aviation, and the new thing
about that was we involved the aviation industry, it was done
at the request of ICAO, the International Civil Air Transport
Organisation, they were involved in setting it up, they helped
us to involve the aircraft industry, that is the manufacturers
of aircraft as well as the operators. And that was a very interesting
experience for us, because it was very good to work with industry
in that way, and it was very good for them to work with us, because
they learned a great deal in that process.
3. When you went through, a moment ago, the
lists of people that the report could interest and who it could
help, you actually did not mention government, you talked about
the scientists, industrialists, students; would you think those
reports could be valuable to government too?
(Sir John Houghton) Sorry; that was a real omission,
if I missed it out.
4. Okay, fine; so long as it was.
(Sir John Houghton) The main purpose of the IPCC is
to inform governments, of course, because we are an intergovernmental
body, so governments are automatically informed by what we do,
because they actually control what we do and take a substantial
part in what we do. And, further, we are recognised as a key body
to inform the process of the Framework Convention on Climate Change,
which, of course, was signed at the Earth Summit in Rio in 1992;
and there have been various meetings of the Conference of Parties,
we have just gone through COP5, I think, COP6 is due next year,
and the most significant of those was the one at Kyoto, which
formulated the Kyoto Protocol.
5. Now, as I understand it, and I think as this
Committee understands it, the IPCC's second assessment report
has been very influential in developing policy on climate change,
not just here in the United Kingdom but throughout the world.
I wonder if, just in a few moments, you could tell us the processes
by which these assessments were reached?
(Sir John Houghton) Yes. It has gradually evolved,
over the period of the IPCC, since 1988, the object being, as
I say, as I have explained, I think, to involve as many scientists
as we can; and therefore we get lists of climate scientists around
the world, and as many countries as we can. We invite them to
contribute material for our report, that is one of the first things
we do, we invite them to be contributors, we invite nominations
for lead authors to the chapters of the report, from around the
world, we then have a procedure for selecting lead authors and
selecting contributors. Typically, for any given chapter, we will
have between ten and 20 lead authors across the disciplines and
with a suitable geographical mix, or, at least, the best geographical
mix we can achieve, given the requirements of actually doing the
work, of course, at the same time. The chapters then get written
in draft, they then get circulated, informally first, to some
key scientists for them to comment; those comments are taken into
account. They then get circulated again to the whole scientific
community, to anybody who wants to receive it, worldwide, and
review it; that is a completely open invitation to the world scientific
community to carry out reviews of it.
6. It is a form of peer review, is it not?
(Sir John Houghton) It is a peer review; it is the
biggest peer review, I think, which occurs in science, that I
know of, certainly, at the present time.
Mr Beard
7. How much difference of opinion is there between
the people who contribute to this exercise; is it a fairly narrowly
columnated set of views, or is there a wide diversity of them?
(Sir John Houghton) We are taking people, of course,
from very different places, from different disciplines, from around
the world, they have a wide variety of views. They tend to break
down, of course, into things that people are fairly sure about,
as a whole, so you have a consensus of views about the main aspects
of climate change, and then there is a wide diversity of views
about those matters where we are pretty uncertain; and those views
come out in the documents.
8. What are, say, the two biggest areas where
the greatest uncertainty would arise and who would be the larger
numbers of people with different views from the central opinion?
(Sir John Houghton) If you take the feedback effect
of clouds, for instance, the impact of clouds, there is a lot
of scientific uncertainty, if the climate warms up; and there
is no real uncertainty in the fact of global warming, the fact
of climate change, the fact of the greenhouse effect, those are
well-established, scientific matters. But where there is uncertainty
is just how big the feedbacks are, what effect they will have
not only on a global scale but on a regional scale. And one of
the most uncertain of the feedbacks, and that is why I mention
it, is the effect of clouds, because if you increase the average
temperature you increase the amount of water vapour, you change
the cloudiness in some regard, and just how those changes will
affect the climate change itself. And there are observations of
how clouds behave, and there are, of course, models which are
generated to try to explain how they behave and describe how they
behave, to try to fit with the observational scene. And if you
were talking in terms of global average temperature increase that
may occur because of global warming, then you get a factor of
about three between the most negative feedback expected from clouds
by some people, and the most positive feedback expected from clouds
by others. In fact, the situation is probably more complex than
that, because clouds probably behave differently in different
places at different times.
Chairman
9. My final question, before we go to Mr Taylor,
and this is about the summaries that the IPCC makes for policy-makers.
Can you please let us know how these summaries are arrived at,
how they are disseminated to various governments, and how much
scientific and technical information is included in them: how
they are arrived at, how they are disseminated, and how scientific
are they?
(Sir John Houghton) How they are arrived at; it is
the end of the process. The scientific chapters are written by
the scientific community, and reviewed, of course, by that community.
And, finally, a subset of those scientists will write a draft
of a policy-maker's summary; that policy summary then goes out
to review, to the scientific community and to government, those
review comments come back, and a revised text, or a draft revised
text, is produced, with options in it, brackets, and so on, which
is then presented to an intergovernmental meeting. That intergovernmental
meeting, typically, will have of the order of 100 countries present,
it will have government delegates, it will have the main lead
authors, the convening lead authors, representative lead authors,
for all the chapters, representing the scientific community, and
we go through that document, word by word, sentence by sentence,
and try to reach agreement, in that big meeting, on the text.
Now that is quite a big task, especially as it is conducted, of
course, in simultaneous translation, in six languages, but the
procedure, as we have developed it, is such that, of course, it
is a scientific discussion, it is not a political negotiation,
so the science is either right or it is wrong, or it has to be
expressed in certain different ways in order to make it acceptable
to the scientific community, or, indeed, to be understandable
by the politicians present; and we go through that procedure.
And so far we have actually succeeded in reaching consensus on
all those policy-maker summaries that we have generated; they
are changed a great deal in the process of that meeting, they
are improved in the process of that meeting, each of them has
been substantially improved both presentationally and scientifically
by that process. Because the government delegates demand that
they are clear, they object to things that appear to be inconsistent,
they want sentences that are relevant and that are understandable
by them, and the process of generating that actually creates a
better and more accurate and more acceptable document both to
the scientists and the politicians, as a result of that process.
Dr Jones
10. Can I just remind you that, when you gave
evidence to our predecessor Committee, you said that there was
a weakness in the process of looking at the total international
programme, because there is no UK body which sits over the climate
agenda as the body responsible for making sure that the UK contributes
in a sensible way. Have things improved since then, who is doing
that now, and is enough priority being given in departmental budgets—the
Ministry of Defence and DETR—to research into climate change?
(Sir John Houghton) That is, of course, a different
issue from the IPCC, the IPCC is an assessment body, the IPCC
does not direct research, it makes some suggestions about the
research which is necessary but it is not in any way in charge
of international or national research programmes. That weakness,
which was apparent in 1996, perhaps, when I gave evidence before,
is still there, there is still a problem in putting the whole
of climate science together, not just in the UK but in other countries
too. And that weakness arises because it is a multi-disciplinary
science which is involved; there is the science of meteorology,
oceanography, a lot of biological components now, ecology, and
so on, are all involved in the whole of climate science, not to
mention, of course, also, the social sciences, which also come
into the whole of the picture when you are looking at climate
science problems. And putting all those things together into a
coherent and sensible national research programme is still a difficulty,
because different subjects are addressed in different ways, by
different Research Councils. And, although the Research Councils
are getting together in a variety of ways and it is improving,
it is improving very substantially, I think, from what it was
in 1996, there is still difficulty in putting the total programme
together, and not only nationally but also internationally, because
of this difficulty that there is no one world body that picks
it all up.
Mr Taylor
11. Can I take you back to your earlier comments
about differences between scientists on the whole problem of climate
change? You implied it was a difference of emphasis, but there
are some people who actually do not go along with the consensus
at all, that it is caused by greenhouse gases and carbon dioxide.
How much, as an assessment body, do you take those views into
account?
(Sir John Houghton) We distinguish between those who
put out views who do not know enough science to put out sensible
views, if I might put it that way, and there are some of those
who use the media to put over material which has no scientific
basis and which would be discarded by all respectable scientists
who are working in the field. There are others who disagree with
our conclusions, substantially, in some cases. One of those, in
fact the most distinguished of those, Professor Richard Lindzen,
is one of our lead authors in our current assessment report; he
agreed to join us for that purpose, and he puts over his particular
scientific view, articulately, and there is a lot of debate on
that particular chapter because of his presence. And that, we
feel, is very good, because we want to take into account all the
genuine scientific views which are around, which are important
to the whole debate.
12. But you accept, therefore, that there is
an element of uncertainty about the whole issue?
(Sir John Houghton) It is not a certain science, by
any means, it is quite an uncertain science, in some regards,
but we are much more certain about some things than we are about
others.
13. But would you accept that there might be
different political reactions, or actions, that would stem from
different views? If you take one particular view, that climate
change is entirely the cause of CO2, then the action that government
might take would be different from an alternative conclusion,
that CO2 plays very little part. You mentioned cloud cover earlier.
There is a whole series of possibilities which might cause differences
in the actions that governments need to take?
(Sir John Houghton) That is true, of course, and the
action that governments take will depend on other factors as well,
economic factors, and whether they feel they are going to be losers
or gainers when climate change is actually occurring, or occurring
on a larger scale. But surely there are lots of people also who
are motivated, of course, by their own vested interests, and there
are very strong lobbies, from the energy industry in the United
States, or a very strong oil and coal lobby, which has been very
active, it has been selecting material in an irresponsible way,
in order to try to persuade the US Congress and other bodies in
the US that there is no need to take action of any kind. Now they
are distorting the story very substantially, and the scientists
in the IPCC have been disturbed by that sort of process going
on, supposedly in the name of science, but which is distorting
a balanced view of the science. You see, there is a lot of information,
a lot of data, a lot of observations, a lot of modelling results,
and if you are going to produce a balanced assessment of what
climate change will be, we can say there is uncertainty, we can
say the problem lies between certain limits, and we explain that.
Now, those who want to put over a particular political view, or
a particular vested interest view, will tend to concentrate on
the bottom end, or even below the bottom end, of what might occur.
There are those, of course, on the other hand, people who work
for green organisations, quite often, who will try to say we have
not emphasised the uncertainty anything like enough, and it may
well be that there could be almost calamitous events; they talk
of Armageddons, and things of this kind, in order to try to put
over a much more damaging view of what might occur. What we try
to do, in the IPCC, is to put over a balanced view, given the
nature of the science, given the uncertainties which are involved,
and given our total understanding of it.
Mr Beard
14. To what extent do the dissenters dissent
from the idea that the whole impact of climate change is caused
by the greenhouse effect; and to what extent are there dissenters
who believe that something like sunspots may be a contributory
cause?
(Sir John Houghton) I am sorry? Could you please repeat
the question?
15. To what extent are the dissenters all agreed
that the greenhouse effect is the cause; and to what extent are
there dissenters who believe that there may be some other factor
contributing, like sunspots?
(Sir John Houghton) There are climate changes for
a whole variety of reasons, of course, there are factors which
cause climate change other than the increase of greenhouse gases.
Climate change can occur because the sun is changing, it can occur
because of volcanic eruptions, it can occur just for natural variability
reasons, because of interactions between different components
of the system, between the atmosphere and the ocean, for instance,
which causes natural variability and causes the changes in extremes,
and we have got examples of all those in climate history; and,
if you are going to assess climate change as it occurs now, we
have got to take all those factors into account and say which
is the most important contributor. The scientific community accepts,
the whole scientific community, I think everybody who has any
real scientific knowledge of the subject, accepts that greenhouse
gases, in particular carbon dioxide, are a major cause of climate
change. There are those who say it can all be explained by variations
in the sun; that is not scientifically credible.
16. My question, really, is how much are those
people represented in the range of dissidents that you were speaking
of when you spoke to Mr Taylor?
(Sir John Houghton) The number of scientists who are
working in the climate change field who would argue that it is
all explained by the sun are very few indeed; in fact, there is
probably no credible scientist in the world who would say that.
17. But partly?
(Sir John Houghton) But there are some who pick up
information second-hand and who purvey it and sell it and talk
about it as if—
Dr Gibson
18. Do they publish on it, in reputable journals?
(Sir John Houghton) No.
Dr Turner
19. Sir John, it sounds very much as if much
of the controversy exists amongst those who are not dedicated
primarily to the field; and, indeed, your memorandum notes that
"the IPCC process led to a significant degree of consensus."
That is, presumably, amongst professional scientists devoted to
work on climate change. And you go further, to point out that
sometimes consensus is not a sign of scientific health, argument
and disagreement being useful promoters of scientific advance.
So should we be concerned about the degree of consensus that exists
amongst those who are dedicated to the study of climate change,
or should we take caution in interpreting what they say, simply
because there is so much consensus amongst them?
(Sir John Houghton) The degree of consensus among
them is not perhaps as large as you imagine, but they have consensus
only on some of the basic facts of climate change. The number
of scientists we are talking about are many hundreds worldwide,
we are talking of all the leading scientists in the field, in
a wide variety of disciplines, they are not all working just in
climate, they are working in things, topics, related to climate,
and so on. So we are talking of a very large body of worldwide
scientists who agree about the basic scientific issues which are
at stake; they do not agree about all the detail, there is a lot
of uncertainty in the detail, and that is well explained in the
documents that we produce, and there is a range of possible climate
changes that may occur, and we also try to explain that. As far
as regional change is concerned, there is a great deal of uncertainty
on what we can expect in the future, in any given place; nevertheless,
the fact of climate change, I think, is very clear. The number
of genuine scientists who would be considered as contributors
to any scientific literature who are outside the range of uncertainty
that we give, and who say there is no climate change occurring,
of one kind or another, worldwide, is probably less than ten,
in fact, probably less than five, actually. So we are talking
of very small numbers, but some of those are very strongly used
by the media, over all kinds, because the media are very interested
in people who are right on the edges of what might be considered
to be the general view. That does not mean the general view is
wrong, I think you have to take into account the weight of evidence
of hundreds of scientists worldwide who have spent many hours,
many days, many months, actually, debating it, arguing about it,
as we do. And that, I think, gives great strength to the sort
of IPCC process that we have, in bringing together people of this
kind and getting them to debate it, and actually changing their
view in that process.
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