History of the Hadley Centre for Climate Prediction and Research

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Chris K. Folland
David J. Griggs
John T. Houghton
Met Office, Hadley Centre, Exeter
Brief history of climate
research before the Hadley
Centre
In briefly describing climate research at the
Met Office before the formation of the
Hadley Centre for Climate Prediction and
Research (usually referred to as the Hadley
Centre) in 1990, we concentrate on aspects
related to core activities of the Hadley
Centre involving climate change, its detec-
tion in the observed record, and decadal
prediction. The antecedents of the Hadley
Centre can be traced back to the Met Office
Climatology Research Branch of the 1950s
and early 1960s, known as Met O 13. In 1963
this branch was divided into two parts, the
Synoptic Climatology Branch that remained
as Met O 13 with the task of developing and
issuing long-range weather forecasts, and a
new Dynamical Climatology Branch, Met O
20. This new branch was mainly tasked with
the physical and dynamical analysis of the
atmospheric (and later oceanic) general cir-
culation, and the development of dynamical
climate models. The unusually severe winter
of 1962/63 provided an impetus to this new
development in climatological research.
Could the Met Office have issued a better
forecast of that winter than the real-time
forecast issued by the USA? Also, what were
the causes of such events and the under-
lying mechanisms of the general circulation
– one of the unsolved problems in meteor-
ology at that time (Gilchrist, personal
communication; Meteorological Office
1964)?
Suggestions of the influence of increasing
CO2from human activities on the climate
system go back to the nineteenth century,
notably Arrhenius (1896). In the Met Office,
this became an issue in the 1970s, spurred
on by measurements of increases of CO2in
the atmosphere in Hawaii that commenced
in the late 1950s. This led to meetings organ-
ised by the Director-General, John Mason,
with other UK government departments,
though it was to take a decade longer for
these discussions to lead to significant polit-
ical interest. However, technical discussions
continued at the European level (Gilchrist,
personal communication). The key to
scientific progress in the 1970s lay in the
developments of models of the general
circulation that were well under way.
Experiments with 5- and 11-level atmos-
pheric models (e.g. Gilchrist et al. 1973)
demonstrated the potential impact on
atmospheric circulation and precipitation of
changes in tropical ocean temperatures (e.g.
Rowntree 1976), Arctic sea-ice and soil mois-
ture. Some effects of changes in atmospher-
ic composition in models were first
indicated by experiments exploring the
effects of nitrogen oxides on ozone released
by a projected fleet of stratospheric aircraft.
Of particular note were experiments with a
single-column version of the 11-layer model
assessing the sensitivity of its response
when CO2was increased (Rowntree and
Walker 1978). Development of the tropical
components of the 11-level model received
considerable impetus from the Met Office’s
involvement in the Global Atmospheric
Research Programme Global Atlantic
Tropical Experiment (GATE, e.g. Mason 1976).
An early milestone in the 1980s was the
demonstration with an atmospheric model
of the consequences for climate of equili-
brium global warming under doubled
concentrations of CO2(Mitchell 1983),
including the threat of severe summer
droughts in northern midlatitudes (Mitchell
and Warrilow 1987). By the time the Hadley
Centre was set up in 1990, the Dynamical
Climatology Branch had developed consid-
erable climate modelling expertise and had
made a significant contribution to the first
Scientific Assessment of the Intergovern-
mental Panel on Climate Change (IPCC
1990).
The Synoptic Climatology Branch initially
included Hubert Lamb who was to set up
the Climatic Research Unit in Norwich in
1972. However, research relevant to global
warming started in the 1980s with the
publication of the first quasi-homogeneous
long datasets of worldwide sea surface tem-
perature (SST) and air temperature over the
oceans, and their analysis for change
(Folland et al. 1984). Early work was also
done on climate change detection relating
to the observed increases in CO2(Parker
1985). By the late 1980s the Synoptic
Climatology Branch was working closely
with the Climatic Research Unit to produce
an integrated global land surface air and SST
dataset. This was the primary dataset used
to assess observed global warming in IPCC
(1990).
Genesis of the Hadley Centre
Similar work to that in the Met Office on
climate modelling and the analysis of
climate observations was being pursued
elsewhere in the world (especially in the
USA) during the 1970s and 1980s, and a
significant international interest was dev-
eloping. Two key international scientific
conferences on the possibility of anthro-
pogenic climate change due to the increase
in greenhouse gases were held early in the
1980s, one in 1981 organised by the World
Climate Programme and one in Villach,
Austria, in 1985 organised by the Scientific
Committee on Problems of the Environment
(SCOPE), a committee of the International
Council of Scientific Unions. The latter con-
ference led to an important publication
(SCOPE 29 1986) that described the adverse
effects that could result from continued and
increased anthropogenic emissions of CO2.
Following this, at the 1987 Congress of the
World Meteorological Organization, the IPCC
was formally set up under joint arrange-
ments with the United Nations Environment
Programme.
Three events occurred in 1988 that assist-
ed greatly in bringing the issue of anthro-
pogenic climate change to the notice of
politicians. The first was a World Ministerial
Conference on Climate Change in June host-
ed by the government of Canada. The
second was a speech in September by
Margaret Thatcher, the UK Prime Minister, at
the annual dinner in London of the Royal
Society. Here she mentioned the science of
History of the Hadley Centre for
Climate Prediction and Research

anthropogenic climate change (she was a
trained scientist) and the importance of
action to combat climate change. Mrs
Thatcher pointed out that humans had a ‘full
repairing lease’ on the earth and must act
responsibly to fulfil the terms of that lease.
The third event was the first meeting of the
IPCC in Geneva in November 1988.
Delegates from many countries agreed to
set up an international assessment of the
science of climate change, together with its
likely impacts and the policy options. John
Houghton, then Director-General of the Met
Office, was elected as chairman of the
Science Working Group. Because of the sub-
stantial work involved in carrying out a suc-
cessful assessment, David Fisk, Chief
Scientist of the Department of the
Environment (DoE), agreed that the DoE
would finance a Technical Support Unit for
the IPCC (Working Group I, the Science of
Climate Change) based at the Met Office.
The Science Working Group, led by Geoff
Jenkins (Assistant Director of the Synoptic
Climatology Branch), held its first meeting at
Nuneham Courteney, Oxfordshire, in
December 1988, attended by over 100
scientists. This introductory meeting was
addressed by Nicholas Ridley, Secretary of
State for the Environment. He announced
that the Government was committed to
extending its influence internationally to
provide information about climate change
and to supporting appropriate research.
Accordingly, discussions were held with the
DoE to strengthen climate research at the
Met Office. A draft proposal was prepared in
the first half of 1989 led by Keith Browning
(Director of Research), Peter White (Director
of Dynamical Research), Geoff Jenkins and
Howard Cattle (Assistant Director of the
Dynamical Climatology Branch), and Alan
Apling of the DoE. Further planning was set
in motion by a Climate Centre Coordinating
Committee consisting of Met Office scien-
tists. This led in November 1989 to an
announcement by Chris Patten, Secretary of
State for the Environment, of a new centre
for climate change research in the Met
Office that would unite observational and
modelled climate research. In particular,
predictive climate modelling was to be sub-
stantially expanded with a contract of about
£5.5 million per year from the DoE. A build-
ing of the right size adjacent to the Met
Office’s main building was secured to house
the new centre (Fig. 1).
Demonstrating her continuing interest in
climate change, Margaret Thatcher invited
John Houghton to present the scientific
findings of IPCC (1990) to her Cabinet on 21
May 1990. This assessment received its inter-
national endorsement at an intergovern-
mental meeting in Windsor on 24 May 1990.
In her speech opening the Hadley Centre on
the very next day (Fig. 2), Mrs Thatcher used
the opportunity to publicise the IPCC
findings and to express her enthusiasm for
the work of the new centre. She said:
“The work of this centre . . . with its
advanced computing facilities and the
superb skills of its scientists . . . will help
us look into the future and predict more
precisely the changes in our climate.
Previously we could get some idea of
future climates by observing and
analysing the patterns of the past. But
the changes we can expect in the future
will be so much greater than anything we
have hitherto experienced, that these
methods will not be adequate and we
shall need to rely much more on com-
puter models which take in the full
complexity of the climate system.”
Since the first IPCC Assessment in 1990,
two further comprehensive assessments
have been completed in 1995 and 2001.
Each has been characterised by the involve-
ment of the Hadley Centre, together with
hundreds of other scientists from many
countries as authors or reviewers. The
extremely thorough processes of review
developed by IPCC ensures that the
Assessments are authoritative and have
wide ownership by the global scientific and
government communities. The 1990 Report,
extensively contributed to by scientists in
the Dynamical and Synoptic Climatology
Branches, and its Supplementary Report in
1992 were essential to the international
agreement that led to the signing by 160
countries of the Framework Convention on
Climate Change at the Earth Summit in Rio
de Janeiro in 1992. Subsequent IPCC Reports
have provided support to the negotiations
at meetings of the Conference of Parties
(COP) of the Framework Convention inclu-
ding those leading to the Kyoto Protocol in
1997.
The aims of the Hadley Centre
The Hadley Centre was named after George
Hadley, an eighteenth-century British scien-
tist who was one of the first to point out the
importance of the earth’s rotation in deter-
mining the atmosphere’s circulation (Hadley
1735). The Hadley Centre soon established
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History of the Hadley Centre
Fig. 1 The Hadley Centre building in Bracknell, 1990–2003
Fig. 2 Opening of the Hadley Centre building by Mrs
M. Thatcher, Prime Minister, 25 May 1990

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319
itself as a leading centre in the world in
climate research and climate modelling. Its
main objective is to provide to government
and the public an authoritative assessment
of both natural and man-made climate
change. The strategic aims of the research
programme are:
(i) To understand the processes in-
fluencing climate change and to
develop climate models.
(ii) To analyse the observed climate
record, including monitoring of
climate in near real time and the
extent of natural variability.
(iii) To detect climate change and assess
the extent to which climate change
can be attributed to specific causes.
(iv) To use models to predict climate
change, including a full assessment
of the uncertainties.
(v) To advise government policy on the
mitigation of, and adaptation to,
climate change.
(vi) To provide a focus for relevant
national research programmes and
use results from them.
The initial plan for the Hadley Centre’s
climate change research (Meteorological
Office 1990), developed with Dr Fisk of the
DoE, was for the 15 years to 2005. This plan
is very well reflected in the achievements of
the Hadley Centre since 1990. Space does
not allow detailed discussion of the numer-
ous collaborative projects, national and
international, but it is acknowledged that
these many collaborations have been very
important to the Hadley Centre. Also key has
been the leadership of its Directors, David
Carson (1990–99), Alan Thorpe (1999–2001)
and David Griggs who has led the Centre
since 2001.
A background factor of importance dur-
ing the Hadley Centre’s existence has been
rising global surface temperatures as pre-
dicted at the start of the Centre’s existence,
broadly mirrored for the UK by the beha-
viour of the Central England Temperature
record (Parker et al. 2004). Another factor of
much importance has been the great bene-
fit that Hadley Centre models have had from
investments in model parametrization and
dynamics funded by the Met Office’s numer-
ical weather research programme under the
Unified Model concept.
Early achievements to 1995
The first major modelling achievement was
the completion in 1991 of the first transient
climate change experiment conducted with
the first Hadley Centre coupled model (11
atmospheric levels, 17 ocean levels, resolu-
tion 2.5° × 3.75°) (Murphy and Mitchell
1995). This was a major step forward
(though one other centre, the Geophysical
Fluid Dynamics Laboratory at Princeton, had
also achieved this), because most previous
experiments had been carried out for an
equilibrium climate change corresponding
to a doubling of CO2and had not used time-
varying increases. At that time, the model’s
radiation scheme did not allow the full
range of greenhouse gases to be included.
So a scenario was used with CO2increasing
at 1% per year for 70 years to achieve a
doubling at the end of the period – the
‘equivalent CO2’ approach. Key conclusions
were that there was likely to be more warm-
ing in the Northern than the Southern
Hemisphere, reduced warming in polar
regions compared to ‘equilibrium’ experi-
ments, and little surface warming in some
high-latitude oceanic regions in the North
Atlantic and Southern Ocean.
A problem was a delayed start to the
warming – the ‘cold start’ problem. This
arises because the model ocean initially
takes up heat without significant warming.
However, simulation of climate change from
today requires that the model has already
responded to past greenhouse-gas
increases. The potentially important offset-
ting cooling effects of anthropogenic
sulphate aerosols were also not included.
These results were, nevertheless, an impor-
tant contribution to the IPCC Supplementary
Report (IPCC 1992). Using a version of this
model, the Hadley Centre was also central to
exposing the biggest single uncertainty in
the science of climate change prediction,
the problem of cloud feedbacks (Senior and
Mitchell 1993). These can greatly affect the
warming and therefore the ‘climate sensiti-
vity’ to doubling CO2. The problem remains
acute today.
In 1992, a significant observational mile-
stone was the creation of the world’s first
integrated dataset (from 1870) of global SST
and sea-ice extent, the Global Sea Ice and
Sea Surface Temperature dataset. This and
its successors, now the Hadley Centre Sea
Ice and Sea Surface Temperature Dataset
(HadISST1.1, Rayner et al. 2003), have been
widely used worldwide in simulations of
climate variability and change, and to eval-
uate a number of coupled models, including
the Hadley Centre’s. HadISST was also used
in IPCC (2001) as the key dataset to assess
changes in sea-ice extent.
A major step forward in 1995, using the
Hadley Centre’s second coupled model
(HadCM2, Johns et al. 1997) (part of the Met
Office's unified climate and weather fore-
casting model with a 2.5° × 3.75° horizontal
resolution and 19 atmospheric and 20
ocean levels), was the incorporation of sul-
phate aerosol cooling in climate change
predictions and in simulations of the last
century (Mitchell et al. 1995). Both the direct
effects of the aerosols and some of the ‘in-
direct’ cloud effects (Jones et al. 1994) were
estimated. A fully developed model of
sulphate aerosol emissions, advection,
chemistry and washout with interactive
radiative effects was not yet feasible, so a
parametrization using surface albedo was
used. This gave considerably better agree-
ment with the observed temperature
record. It was the first time incorporation of
sulphate aerosol effects in a fully coupled
simulation had been achieved by any centre
and provided a major input to IPCC (1996).
The ability to simulate better the observed
record of global temperature also con-
tributed to advances in climate change
detection and attribution in IPCC (1996), par-
ticularly to the major conclusion that “the
balance of evidence suggests a discernible
human influence on climate”. The work also
influenced the first COP held in Berlin in
spring 1995 for which a special brochure
was produced.
Global climate models do not yet have
sufficient resolution to resolve climate on
small scales, especially the climate of rainfall
when appreciable topography is present
(though this situation could change fairly
soon with models run on the Japanese Earth
Simulator). Consequently, regional climate
models have been developed that are
driven at their boundaries by the coarser
global models. They are particularly needed
for realistically investigating the climatology
of rainfall extremes and therefore estimat-
ing changes in such extremes. The first,
50 km resolution, version of the Hadley
Centre regional model was developed in the
mid-1990s and integrations with doubled
CO2were made for western Europe and for
India for IPCC (1996). Notably it was found
that the hydrological cycle was more
intense than in the driving global model.
Progress since 1995
A major question of importance to the
politicians meeting at the COP of the
International Framework Convention on
Climate Change has been the detection and
attribution of climate change in the
observed record. The Hadley Centre has
been represented at each annual COP meet-
ing. Particularly important was COP3 held in
Kyoto, Japan, in 1997, though the resulting
protocol on national greenhouse-gas emis-
sions remains to be ratified. A brochure was
produced for COP3 which showed that
modelled changes of temperature through
the depth of the atmosphere were similar to
those observed only when changing
anthropogenic forcings were added to
HadCM2, adding to the observed evidence
for climate change (Tett et al. 1996).
Temperature observations were obtained
from a new Hadley Centre radiosonde tem-
perature dataset (Parker et al. 1997).
Since that time ‘optimum detection’ tech-
niques have been developed to detect and
attribute climate change that maximise the
ratio of the greenhouse-induced signal to
History of the Hadley Centre

the internal noise variability (e.g. Stott et al.
2000). Notable contributions in this area
were made to IPCC (2001) which influenced
the much stronger conclusion in that report
that “there is new and stronger evidence
that most of the warming observed over the
last 50 years is attributable to human activi-
ties.” Recently, anthropogenic signals have
also been detected in large-scale atmos-
pheric circulation (Gillett et al. 2003). A goal
of climate change detection and attribution
is attribution on scales like that of the UK.
Using different modelling and statistical
techniques, a significant step towards this
goal was made at the Hadley Centre by
Sexton et al. (2003).
A problem with many climate datasets
used for detecting climate change is a lack
of objective estimates of uncertainty. The
Hadley Centre has started to develop such
methods, creating the first objective esti-
mates of uncertainty in the global surface
temperature series (Folland et al. 2001). This
led to the IPCC (2001) conclusion that global
temperatures increased over the twentieth
century by 0.6 ±0.2 degC.
A key development was the third Hadley
Centre climate model, HadCM3 (Pope et al.
2000; Gordon et al. 2000), extensively used
in the IPCC Third Assessment Report.
HadCM3 solved a major problem of previous
coupled models where artificial fluxes of
energy had to be imposed at the ocean sur-
face to keep ocean surface temperatures
from drifting. These ‘flux corrections’are not
used in HadCM3, although it was not quite
unique in this respect at the time of IPCC
(2001). HadCM3 has a 2.5° × 3.75° resolution
in the atmosphere but a higher 1.25° × 1.25°
resolution in the ocean with 19 atmospheric
and 40 ocean levels. HadCM3 also has a
much more advanced radiation scheme
(Edwards and Slingo 1996), allowing the
long-wave radiative effects of all green-
house gases to be individually modelled. In
addition it has an interactive sulphur cycle
that models the complete cycle from emis-
sions to washout (Johns et al. 2003). The
sulphur cycle also interacts with the clouds
to estimate the ‘indirect effect’ of sulphate
aerosols on the radiation balance. This
uncertain but quite large effect offsets some
of the effects of increasing greenhouse
gases. HadCM3 contains detailed sub-
models of land surface interactions, ocean
and land biology, and therefore the carbon
cycle. HadCM3 is also run interactively with
a separate interactive atmospheric chem-
istry model called STOCHEM (Johnson et al.
2001) that allows changes in many of the
trace greenhouse gases in a warming
climate to be more realistically modelled.
Sea-ice is also more realistically modelled.
Two particular uses of this model were
remarkably accurate simulations of global
temperature over the period of the
observed record and a demonstration in a
further development of HadCM3 that the
carbon cycle is likely to interact with future
global warming so as to accelerate it. Figure
3 shows simulations of observed global sur-
face air temperature (red) using HadCM3
forced with all the known and quantifiable
anthropogenic forcings at the time as well
as the natural effects of volcanoes and solar
variability, taken from Stott et al. (2000).
Grey areas represent the uncertainty due to
internal atmospheric and ocean variability
in the four simulations. The fit to the
observed data is close; the model picks up
the varying rate of observed warming,
including the slight cooling from about
1940 to 1975. Integrations using changing
greenhouse gases alone, or natural effects
alone, give much worse fits to observations.
Figure 4 shows the potential importance
of interactions between the carbon cycle
and global warming. HadCM3 was run with
a particular scenario of increased green-
house gases with and without carbon cycle
feedback. The carbon cycle is likely to posi-
tively feed back on global warming, further
increasing CO2concentrations beyond
those produced anthropogenically. This
partly arises through modelled dieback of
the Amazon rainforest after 2050 and partly
through enhanced CO2emissions from the
warmer soils. Although the cooling contri-
bution of sulphate aerosols is not included
in Fig. 4, a substantial part of the difference
between the red and blue curves would still
be expected, especially after 2050 (Cox et al.
2000).
As mentioned above, regional modelling
is crucial to prediction of climate impacts on
smaller scales. A portable regional model
that can be run on a personal computer has
been developed for use anywhere in the
world under the Providing Regional
Climates for Impacts Studies initiative
(Meteorological Office 2002). This allows any
country to assess its own susceptibility to
climate change and to compare its observed
data against simulations of recent climate
change. Figure 5 shows the impact of the
50 km resolution regional model on simu-
lating the mean annual rainfall climate of
the UK compared to HadCM3. A 25 km
model is now available, with a 10 km model
for smaller regional domains being devel-
oped. Through the regional model, a strong
link has been built up with the UK Climate
Impacts Programme (UKCIP) that was found-
ed in 1998. Thus the 50 km model was used
to generate the updated UKCIP02 climate
scenarios based on four different assump-
tions about future greenhouse-gas emis-
sions and announced in 2002 by Margaret
Beckett, Secretary of State for Environment,
Food and Rural Affairs.
Progress with the development of Hadley
Centre models is summarised in Fig. 6. This
shows the evolution of climate models from
purely atmospheric models in the 1960s to
the much more comprehensive models of
today. Thus the next generation of Hadley
Centre models now in the final stages of
development will be based on the new
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320
History of the Hadley Centre
Fig. 3 Simulation of global temperature, 1861–1999, by HadCM3 Fig. 4 Global warming over land under the IS92a scenario using HadCM3 with
and without carbon cycle feedback using 10-year running means. The IS92a
scenario represents a medium to high level of anthropogenic emissions of
greenhouse gases from 1990 to 2100. No sulphate aerosols are included.
Temperature Change over land (deg C)
with carbon cycle
without carbon cycle

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321
Hadley Centre Global Environmental Model
(HadGEM1). The last item on the top line of
Fig. 6 reflects the aspiration beyond
HadGEM1 to make integrated assessments
of some of the impacts of climate change on
society.
Many users are interested in shorter time-
scales than the 50–100 years typical of
climate change predictions. A decade (or
less) is typical and is a time-scale on which
natural variability is likely to be dominant,
though long enough for anthropogenic
trends to be sometimes visible. Decadal pre-
diction uses coupled models as its basic
tools, but the initial state of the global
oceans is also important. So, unlike climate
change prediction efforts to date, decadal
prediction is a mixed initial value, anthro-
pogenic and natural forcing problem,
involving accurately sampling the initial
state of the oceans down to perhaps 2000 m
depth. New technology, in the form of a
globally distributed system of (by 2007)
3000 temperature and salinity ARGO floats
sampling down to 2000 m, has the potential
to greatly help this enterprise. (ARGO is not
an acronym; for an explanation see
http://www.argo.ucsd.edu/FrOrigins_of_
Argo.html.)
Given a knowledge of SST, the potential to
predict atmospheric circulation and temper-
ature in the North Atlantic region has been
identified by Rodwell et al. (1999). However,
uncertainty remains as to whether this
translates into real predictability when the
SSTs also need to be forecast. Nevertheless,
this is a tantalising pointer to useful inter-
annual to decadal predictions for the United
Kingdom (Fig. 7).
Dangerous anthropogenic
climate change
One purpose of the 1992 Framework
Convention on Climate Change is to avoid
‘dangerous’ anthropogenic climate change.
The Convention does not define what this
level of climate change is but a candidate
has emerged. One consequence of global
warming is sea-level rise. This is due both to
the expansion of ocean waters as they warm
and to the melting of glaciers and ice sheets.
Recently Gregory et al. (2004) demonstrated
that, under most of the future global warm-
ing scenarios currently foreseen, irreversible
melting of much or all of the Greenland ice
sheet may commence later this century.
Once warming in the Greenland area
persistently exceeds about 3 degC above
present levels, melting would occur suffi-
cient to result in the eventual collapse of the
ice sheet and a rise of sea-level of up to 7 m,
spread over 1000 years or more. Persistent
CO2levels of greater than 450 ppmv may be
sufficient for this to happen. A 7 m
sea-level rise would drown vast tracts of
inhabited high-quality land and many of the
world's major coastal cities. Once melting
has occurred, the Greenland ice sheet might
not re-form even under current climate
conditions.
Not all aspects of climate change have
negative implications for society. Thus CO2
fertilisation of some types of plants and
trees, and the warming of potentially fertile
regions currently too cold for economic
food production, could have positive eco-
nomic effects. Overall, however, adverse
effects outbalance the benefits especially in
the longer term.
A forward look
The continued aim of Hadley Centre
research will be to advance our understand-
ing of climate change, and our correspond-
ing predictive capability, in order to ensure
that government policy is based on the
highest-quality science. As we enter the
twenty-first century, both climate science
and policy are faced with profound ques-
tions to be answered and new challenges to
be faced.
Climate models will continue to be central
to the Hadley Centre programme. As our
knowledge base improves, it is increasingly
apparent that more emphasis must be
placed on the linkages among biological,
physical, chemical, and human-related
processes and feedbacks, and on societal
impacts, and this is beginning to steer the
science of global environmental change in a
new direction. The future will involve using
ensembles of state-of-the-art, high-resolu-
tion, global earth system models, which
allow the effects of nonlinear ‘surprises’, vari-
ability, and extreme events to be integrated
History of the Hadley Centre
Fig. 5 Simulated annual mean UK rainfall climatology using HadCM3 (a), the HadCM3 regional model (b)
and observations resolved on the 10 km space scale (c)
Fig. 6 D evelopment of Hadley Centre climate models, 1960s–2004 decadal prediction
2001
1960s
1970s
1980s
1999
1992
1997

in a self-consistent way within the proba-
bilistic framework required by societal risk
assessment. In this way it will be possible to
address issues relating to possible future
trends in the frequency and severity of
extreme events, and the threshold at which
risk of ‘dangerous’ climate change might
become significant. Examples are the disin-
tegration of the West Antarctic or Greenland
ice sheets, collapse of the North Atlantic
thermohaline circulation, or catastrophic
releases of methane from gas-hydrates.
However, in order to do this effectively,
much more powerful computers will be
required.
As they have always been, observations
will also be crucial to the Hadley Centre
research programme. Since the inception of
the Hadley Centre there has been a worry-
ing decline in some traditional and long-
standing forms of observations that are still
much needed, though new sources of data,
e.g. from satellites, have become more
prevalent. It will be important for the Hadley
Centre to play a strong role in international
initiatives such as the Global Climate
Observing System to ensure that we are able
to produce the new and important datasets
that will provide key tests of the model sim-
ulations and hence of our understanding of
the climate system. These scientific
advances will continue to play a crucial role
in policy development. At present the scien-
tific uncertainties continue to dominate the
political agenda as they look to find a politi-
cal way forward towards mitigating climate
change. It is essential that these discussions
continue to be informed by the best poss-
ible science. However, there is an increasing
recognition that a significant degree of
climate change is inevitable and so the
focus is turning increasingly towards adap-
tation. Just as with mitigation, it is essential
that adaptation to climate change is
informed by the best possible science.
However, the Hadley Centre cannot do all
this alone. As climate models become more
complex and begin to incorporate new
areas of science, such as biology and chem-
istry, no one centre will be able to have all
the expertise needed. Much closer collabo-
ration between the Hadley Centre and other
institutions within the UK, Europe and
worldwide is both desirable and inevitable.
In summary, two particular factors have
strongly contributed to the success of the
Hadley Centre. First, the Centre is an integral
part of the Met Office which brings benefits
of synergy with the science and technology
of weather forecasting, together with the
advantages of being associated with the
Office’s operational activities. Secondly, the
links and co-operations resulting from the
close connection with the assessment activ-
ity of the IPCC have also been particularly
important. In addition, the future success of
the Hadley Centre will depend on maintain-
ing the following three key elements:
(i) Top-quality staff in an effective
management structure with strong
partnerships with others.
(ii) Competitive supercomputing.
(iii) A focused programme driven by
policy requirements, supported by a
continuity of funding.
As the reality of anthropogenic change
becomes more apparent and the imperative
of human responses and actions more
urgent, the need for high-quality analyses of
the underlying science becomes even more
widely recognised. The Hadley Centre can
look forward to continuing its contribution
to helping solve one of the most serious
problems facing humankind in the twenty-
first century.
More information on Hadley Centre
activities can be found at: http://www.
hadleycentre.gov.uk/research/hadley
centre/index.html.
Acknowledgements
The authors wish to acknowledge advice
from David Carson, Howard Cattle, Andrew
Gilchrist, Jonathan Gregory, Geoff Jenkins,
Tim Johns, Colin Johnson, Paul van der
Linden, Gordon Lupton, Mark Rodwell, Peter
Rowntree, Adam Scaife, Alan Thorpe and
Peter White.
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Correspondence to: Prof. C. K. Folland,
Met Office, Hadley Centre, FitzRoy Road,
Exeter EX1 3PB.
e-mail:chris.folland@metoffice.gov.uk
doi: 10.1256/wea.121.04
© Crown copyright, 2004.
History of the Hadley Centre