Memorandum submitted by Sir John Houghton
CBE, Co-Chairman of Working Group I of the Intergovernmental Panel
on Climate Change (IPCC)
1. The IPCC was set up in 1988 jointly by
two United Nations bodies, the World Meteorological Organisation
and the United Nations Environment Programme, its purpose being
to provide authoritative assessments of anthropogenic climate
change. Three Working Groups (WGs) were formed, WGI to assess
the Science of Climate Change and WGs II and III to assess the
impacts, adaptation, mitigation and policy options associated
with Climate Change. I have served as WGI Chairman or Co-chairman
(each WG now has two co-chairs one from a developed country and
the other from a developing country) since 1988.
2. Annex I describes the IPCC and its workings
in some detail. I am also sending for members of the Committee
copies of the Summary for Policy Makers and the Technical Summary
of the IPCC 1995 Report.[1]
The essential points to note are that (1) through the involvement
of a high proportion of the world's climate scientists (including
many of the world's leading scientists in the area) ownership
of IPCC reports by the world scientific community has been achieved,
and (2) through the involvement of governments in the review process
and in the approval of the Summary for Policymakers, ownership
of the reports by the world's governments has also been achieved.
The IPCC has therefore played a key role in advising governments
on the science, the impacts and the policy options regarding climate
change.
3. The UK Meteorological Office has been
involved in research into Climate Change since the 1960s when
there was concern that human alteration of the climate might be
used as a military weapon. Because of its strong capability in
atmospheric and ocean modelling it became one of the world's leading
centres in climate modelling, a position which was further strengthened
by the establishment of the Hadley Centre in 1990 with joint funding
from the Department of the Environment and the Ministry of Defence.
The Hadley Centre also houses the Technical Support Unit (TSU)
for WGI of the IPCC, a small group that organises the international
process for the preparation and review of the IPCC reports. The
availability of the best scientific and technical advice especially
from the Hadley Centre and the IPCC has enabled the UK government
to play a crucial role in the international negotiations concerning
climate change in the context of the Framework Convention on Climate
Change (FCCC).
4. I now address the particular questions
raised in your letter to me requesting evidence.
5. Question 1. What other reasonable potential
alternative explanations for climate change, other than increasing
levels of CO2 exist? How does the IPCC assess these? How are its
funds disseminated?
First it is important to recognise the substantial
natural variability of climate that arises especially because
of interactions between the various components of the climate
system (the atmosphere, the oceans, the land, the ice and the
biosphere). Superposed on these variations are climate changes
due to changes in factors that influence the climate. These factors
may be due to natural causes (eg changes in solar radiation or
volcanic eruptions emitting large quantities of dust into the
atmosphere) or to human activities (eg emissions of "greenhouse"
gases such as CO2, methane etc or of gases such as SO2 that lead
to the production of particles in the atmosphere). In any assessment
of past or future climate change all of these need to be considered.
A large proportion of the IPCC reports is concerned with careful
assessment of the available evidence from observations and from
appropriate analysis (including modelling) regarding these factors,
both natural and anthropogenic. The IPCC's clear conclusion stated
in all its reports is that the influence of the anthropogenic
factors, especially emissions of CO2 is likely to be by far the
dominant factor determining climate change during this century.
Regarding the dissemination of IPCC funds, these
are used for the support of a small international secretariat
in Geneva, for the cost of IPCC meetings and for the cost of the
participation of scientists from developing and EIT countries
in IPCC meetings including those of the Working Groups. This latter
is essential if the IPCC is to involve scientists from a wide
range of countries in its work. In addition, the UK government
provides funds to support the WGI TSU to which I referred above.
The IPCC is a cost effective organisation and considering its
work load it employs comparatively few staff.
6. Question 2. Do you think the Government
sufficiently scrutinises alternative explanations for climate
change, other than increasing concentrations of CO2 before developing
policy? By what means is this achieved? What part does the IPCC
play in this?
As I explained in (5) above the variety of factors
influencing climate change is well understood by government, the
main source of comprehensive information available being the IPCC
assessments. These assessments distinguish clearly between what
is known with reasonable certainty and the areas where there is
a lot of uncertainty and debate amongst scientists. Since the
hundreds of scientists involved with the IPCC come from a wide
range of countries, backgrounds and scientific disciplines, a
wide range of genuine scientific opinion is represented. One of
the leading "sceptics", Professor Richard Lindzen, is
a lead author for one of the chapters of the IPCC report currently
in preparation. However, there are a few scientists, many of whom
are supported by fossil fuel companies, who tend to employ the
media rather than the scientific literature to express their view
that the IPCC is overstating the role of greenhouse gases in climate
change. There are a few others, many of whom are involved with
"green" groups, who equally vocally complain that the
IPCC fails to recognise adequately the more damaging anthropogenic
effects on climate that might possibly be realised. Inevitably
too there are others with very limited or no real scientific knowledge
who use the media or who are used by the media to put forward
contrary views. The government is therefore made aware of and
exposed to (and sometimes replies to) the wide range of views
that exist both scientific and political.
7. Question 3. Do you agree that climate
change models provide the most robust means of gaining information
on which to base policy decisions? What other means could or should
be used?
The available scientific evidence comes from
observations, analysis of observations and models. It is sometimes
thought that these are alternative sources of evidence. That is
not the case. Observations on their own are of limited use; they
need to be interpreted. Models provide the main means for the
interpretation of the wide range of observations that are relevant
to climate change. Observations are therefore input to models;
models are of limited value without observations.
Climate models are generated from the equations
that express the physical and dynamical laws that determine the
response of the atmosphere, the oceans and other parts of the
climate system to the natural or anthropogenic factors controlling
the climate that I mentioned in para (5) above. The simplest possible
climate model is just one of these equations. Models as used in
climate science, therefore, possess a sound scientific basis.
Their importance arises from the fact that they are an essential
tool for gaining understanding. Because all the influences on
the climate lead to non-linear responses (ie there is no simple
proportionality between forcing and response), without the use
of models it is impossible to sum the responses of the climate
to the various influencing factors. There are those who speak
loudly about the inadequacies of models and try to use hand-waving
arguments instead. It is true that, because of the complexities
of the climate system, models are inadequate in various respects
and have to be carefully appraised. However, hand-waving arguments
can in no way replace even the simplest of models because they
are completely unable to allow for the non-linear character of
the factors involved.
8. Question 4. What actual appraisal of
climate change models has been performed by Working Group I of
the IPCC and with what conclusions?
The IPCC reports contain results from and assessments
of a wide variety of models covering different aspects of the
problem of climate change—for instance models of the carbon
cycle, of aerosol production, of atmospheric processes an circulation,
of ocean circulation etc. The most sophisticated models are those
that couple together the atmospheric and oceanic circulations
together with descriptions of the hydrological cycle and the behaviour
of sea ice. The large number of studies comparing results from
different models have provided an important input to the IPCC
assessment process; a substantial proportion of IPCC reports has
been taken up with the comparative appraisal of model results.
The IPCC's conclusion regarding the use of models expressed in
the Summary for Policymakers of the 1995 Report is as follows:
"The increasing realism of simulations of current and past
climate by coupled atmosphere-ocean climate models has increased
our confidence in their use for projection for future climate
change. Important uncertainties remain, but these have been taken
into account in the full range of projections of global mean temperature
and sea level change". Confidence in models has increased
further since 1995 as model development has continued and as models
have been tested more thoroughly and over a greater range of conditions.
1 March 2000
1 Not printed. Back
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