Rapid brochure
Source: environment.data.gov.uk (2018-06-19)

RAPID: Numerical meteorological model output data from the HadCM3 control ensemble. Data from "The Predictability of rapid climate change associated with the Atlantic thermohaline circulation" project. This was a Natural Environment Research Council (NERC) RAPID Climate Change Research Programme project (Round 2 - NE/C509174/1 - Duration 1 Jan 2005 - 18 Sep 2008) led by Prof Rowan Sutton of the University of Reading, with co-investigators at the University of Oxford and at the National Oceanography Centre. The dataset identifies the dominant sources of uncertainty in General Circulation Model predictions of the Thermohaline Circulation. 

This dataset contains meteorology model output from the HadCM3 control ensemble.

Forecasts of the future behaviour of the Atlantic Thermohaline Circulation (THC) are needed to inform policy on climate change. Such forecasts must be probabilistic taking into account the principal sources of uncertainty. It is not possible to sample exhaustively all sources of uncertainty because the number of degrees of freedom is too great. Consequently a future forecasting system will be reliant on strategies to identify those dimensions of uncertainty that are most important. This project developed an objective methodology to identify the dominant sources of uncertainty in General Circulation Model predictions of the THC. Perturbations to oceanic initial conditions and climate model parameters that generate the most rapid change in the THC and related aspects of climate were identified. These perturbations were used to produce an early probabilistic forecast for the behaviour of the THC up to 2100. The results were also feed directly into the next generation of ensemble climate predictions being developed at the UK Hadley Centre.

Rapid Climate Change (RAPID) was a £20 million, six-year (2001-2007) programme for the Natural Environment Research Council. The programme aimed to improve the ability to quantify the probability and magnitude of future rapid change in climate, with a main (but not exclusive) focus on the role of the Atlantic Ocean's Thermohaline Circulation.

RAPID  CLIMATE  CHANGE
The Rapid Climate Change programme

Executive summary	
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PAST	
Understanding the past – rapid cooling 8200 years ago	
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PRESENT	
The Atlantic array – the first continuous measuring system	
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FUTURE 
The day after tomorrow – modelling, prediction and forewarning	 14
Contents
R A P I D  C L I M AT E  C H A N G E
Cover photo©iStockphoto.com/Alexander Hafemann

Knowledge exchange	
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Inspirational outreach	
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Rapid WATCH – next steps 2008-2014	
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Projects and contacts	
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Introduction
Society is performing a giant experiment on humanity’s life-
support system. Pre-industrial atmospheric carbon dioxide 
concentrations were 270 parts per million (ppm): in 2008, 
they reached 385ppm. They are currently increasing by 2ppm 
a year. The world is approaching the 450ppm limit widely 
thought necessary to avoid dangerous and possibly irreversible 
climate change. To borrow a phrase from the US physicist 
Richard Feynman, tickling the dragon’s tail is a dangerous 
game: the consequences may be rapid and irreversible. It is of 
the greatest importance that we improve our understanding 
of the planet’s climate system and the likelihood of abrupt 
changes to it. Nations are not responding quickly to the risk of 
global warming but the UK research community is taking an 
international lead in this area.
The oceans and rapid climate change
The oceans control Earth’s climate over decades to centuries, 
so understanding how they are changing is the key to choosing 
appropriate climate change mitigation and adaptation 
measures. Many estimates of future change are based on 
forecasts from climate models that predict gradual climate 
responses, more or less proportional to the steadily increasing 
greenhouse gas concentrations. However, ice and sediment core 
records reveal that in the past climate has changed abruptly 
– in as little as 10 to 20 years. This is too fast to implement 
prevention strategies and could make adaptation extremely 
expensive. Quantifying and understanding the ocean processes 
that cause climate to change abruptly – and how they do this 
– is what spurred the Natural Environment Research Council to 
set up the £20 million Rapid Climate Change programme.
From the start of the programme in 2001, a key focus was a 
better understanding of the ocean physics in the North Atlantic. 
Previous research has demonstrated that abrupt climate 
changes in the past can be linked to changes in the overturning 
circulation known to oceanographers as the Atlantic Meridional 
Overturning Circulation (AMOC), and nick-named the Atlantic 
Heat Conveyor because it acts as a conveyor belt transporting 
Executive summary
In 2001, the Natural Environment 
Research Council set up the £20 million 
Rapid Climate Change programme to 
investigate the fundamental processes 
that cause climate to change abruptly. 
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Scientists and engineers from the Rapid 
Climate Change programme deploying the 
array of scientific instruments across the 
Atlantic Ocean at latitude 26.5ºNorth.

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heat northwards. This is part of a much larger global ocean 
circulation system. 
Before the programme, computer models had shown that this 
heat conveyor produces a substantially warmer climate in 
western Europe than would otherwise be the case. The models 
also show that increasing greenhouse gases in the atmosphere 
may cause the circulation to slow, and according to the UN’s 
Intergovernmental Panel on Climate Change Fourth Assessment 
Report (2007) it is very likely that the Atlantic conveyor will 
slow down in the 21st century. As a result, less heat would 
reach western Europe.  While the increased greenhouse gas 
concentrations would still cause a net warming, the local, 
seasonal and less predictable effects of a slowdown give cause 
for concern. In 2006, an independent report from the consultants 
Pricewaterhouse Coopers which analysed the economic 
impact of an abrupt shutdown of the circulation, estimated 
that unforeseen changes in the conveyor leading to rapid and 
unexpected shifts in climate, could cost the world economy 
billions of pounds. But before the Rapid Climate Change 
programme, quantification and understanding of the Atlantic 
overturning circulation relied on sporadic measurements and 
theoretical results.
In 2005, an analysis published in the journal Nature, based 
on five snapshots of the circulation taken between 1957 and 
2001, indicated a possible slow-down of the Atlantic conveyor 
by up to 30 per cent. Crucially, there were no data on daily, 
monthly or annual natural variability. If this information were 
available, it would have determined if such variability was 
contaminating estimates of long-term change. All this has 
now changed. The centre-piece of the Rapid Climate Change 
programme is continuous daily monitoring using a system of 
moorings across the entire Atlantic basin, from the west coast 
of Africa to Miami. The array of scientific instruments is vital 
for researchers to make better predictions of future climate 
changes and their impacts. The success of the pilot scheme 
(2004-2008) has ensured the future of the array until 2014. 

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The bigger picture
For a complete understanding of how climate can change 
rapidly, scientists need to combine information on the past, 
present and likely future. Researchers on the Rapid Climate 
Change programme have focused on past abrupt climate 
changes, particularly 8200 years ago, the current state of the 
overturning circulation, and improving climate models based on 
their findings and new ways of using model results. 
Outcomes
n	 The first continuous daily measurements of the Atlantic 
Meridional Overturning Circulation – the Atlantic Heat 
Conveyor. 
n	 The first evidence of large sub-annual natural variability in 
the strength of the Atlantic conveyor.
n	 Significantly increased knowledge of the nature and causes 
of a major abrupt change in climate 8200 years ago. 
n	 Improved modelling of rapid climate change.
From pilot scheme to decadal measuring system
One clear outcome of the Rapid Climate Change programme 
is the internationally acknowledged need for longer-term 
observations of the Atlantic conveyor, beyond the four-year 
pilot scheme. The Natural Environment Research Council 
has committed £16.1 million to ensure a further six years of 
continuous measurements, up to 2014. Matching funds have 
also been committed by the National Science Foundation and 
the National Oceanic and Atmospheric Administration in the 
United States to complete the transatlantic monitoring array. 
This follow-on programme is called Rapid WATCH (Will the 
Atlantic Thermohaline Circulation Halt?). The Rapid WATCH 
programme is working closely with the Met Office Hadley 
Centre and policy-makers to ensure the measurements are 
used effectively, particularly in decadal prediction systems. 
The Rapid Climate Change programme funded 36 projects. 
Some are complete and have published their findings, 
others are ongoing. This brochure is a selection of some of 
the highlights of the programme.   

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Science into policy
The programme has forged 
close relationships with a wide 
variety of policy-makers  and 
stakeholders and used these links 
to communicate key scientific 
results clearly and effectively.
International partners
The programme has driven 
international cooperation and 
co-funding partnerships with the 
National Science Foundation 
and the National Oceanic and 
Atmospheric Administration 
in the USA, the Netherlands 
Organisation for Scientific 
Research and the Norwegian 
Research Council.
Inspirational outreach
With the publication of major 
research papers, the public profile 
of the Rapid Climate Change 
programme has been very high. 
The team has worked closely with 
writers, journalists, film-makers, 
poets and artists, and specifically 
with the Cape Farewell project, to 
engage with a broad audience. 
Pictures courtesy Capefarewell.com

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There have been times in the Earth’s history when dramatic 
shifts in temperature of almost 15°C have occurred in a matter 
of decades. The largest of these events took place during the 
glacial period (110,000-12,000 years ago), when the world 
looked very different from today. Vast ice sheets covered much 
of North America and Europe. However, even the present-
day warm period, known as the Holocene, has experienced 
dramatic and rapid changes in climate across northern Europe 
and the UK within a human lifespan. 
The most prominent climate shift during the Holocene was a 
rapid cooling 8200 years ago. Scientists have found evidence 
of cooling in the Pacific and Tasmania as well as northern 
Europe. The cause, or at least part of it, is attributed to the final 
collapse of the North American and Scandinavian ice sheets as 
global temperatures rose following the end of the last ice age. 
Large volumes of fresh water swept into the North Atlantic, 
disturbing the sensitive ocean conveyor. Warm water currents 
from the tropical Atlantic slowed down, never reaching higher 
Understanding the past
latitudes. This led to extreme cold and dry conditions across 
much of the North Atlantic region with temperatures in 
Greenland dropping almost 6°C. 
The possibility of future abrupt climate change is dependent 
on the warming and freshening of sensitive areas of the North 
Atlantic. The event 8200 years ago shows how sensitive 
the ocean circulation is to changes in conditions, and how a 
change in the circulation can affect climate. 
What is the evidence?
Scientists find evidence of past climate change in a range of 
different palaeo records such as ice cores, lake sediments, 
ocean sediments and speleothems (stalagmites and 
stalactites). These records contain signals of environmental 
change, such as the amount of snowfall in a year or the amount 
of organic matter (diatoms and other plankton) deposited 
on the seafloor. Researchers on the Rapid Climate Change 
programme collected a range of palaeo records from across the 
Rapid cooling 8200 years ago 
Rapid climate change is something that has 
captured the imagination of the public and 
governments alike. But why are scientists worried 
about abrupt climate change? Quite simply 
because it has happened before.
Assembling the new 18-metre core barrel on board the 
Royal Research Ship Charles Darwin between Scotland and 
Newfoundland, July 2004.

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Key findings
n	 Analysis revealed extreme cold and dry conditions across the North Atlantic (Newfoundland, the UK and 
northern Europe) 8200 years ago. 
n	 Greenland temperatures were almost 6°C colder than present day. 
n	 The shift to colder temperatures took only a few decades and lasted approximately 160 years.
n	 Ocean records reveal colder and less saline surface waters in the North Atlantic and a slowdown in the 
Atlantic Heat Conveyor.
n	 A rush of meltwater into the North Atlantic caused the slowdown and colder conditions. 
n	 Improved model simulations predict that relatively small increases in fresh water could affect the ocean 
conveyor.
The cold event 8200 years ago is clearly observed in the 
stable isotope record from Greenland ice cores. The 
abnormally cold temperatures last 160 years reaching a 
maximum cooling of almost 6°C. 

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North Atlantic region to investigate the cold event 8200  years 
ago. 
North Atlantic gets fresher when the ocean heat 
conveyor slows down
Sedimentary records from ocean cores drilled in the North 
Atlantic as part of the Rapid Climate Change programme show 
a freshening of the North Atlantic surface waters consistent 
with theories that large volumes of glacial meltwater flooded 
the North Atlantic. Scientists believe that this was probably 
caused by rapid flooding from an ice-dammed lake in North 
America. The isotopic compositions of plankton contained 
in the sediments reveal a large decrease in the salinity and 
temperature of the North Atlantic prior to the cooling observed 
from land-based palaeo records.
 
Analysis of the ocean sediments for nutrients, biological 
content and grain size indicates that the southward flow of 
North Atlantic deep water, which drives the North Atlantic 
Heat Conveyor, weakened following the influx of cold fresh 
water from the disintegrating ice sheet. The slowdown in the 
conveyor lasted approximately 100 years.
Colder atmospheric temperatures
The surface temperature of a particular location can be 
determined from the isotopic composition of snow or rainfall. 
In the polar regions (or areas at altitude) the record of past 
precipitation is contained in the snow and ice, which remains 
all year round, and can be retrieved by drilling ice cores. 
Greenland ice cores provide a record of past temperatures 
dating back several thousand years. Investigation of ice core 
sections from the Greenland Ice Core Project (GRIP) revealed 
that 8200 years ago, temperatures in Greenland were almost 
6°C colder than present day, and these cold conditions lasted 
160 years.
Scientists can also reconstruct temperature changes from 
the isotopic composition of calcareous deposits in caves 
Lake sediments from the ISOMAP-UK 
(ISOtope calibration and MAPping) project
Liz Fisher and Jim Marshall collect samples from 
Hawes Water, north-west England.

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(speleothems – stalagmites and 
stalactites), the skeletal remains of 
ocean- and lake-dwelling creatures, and 
even mosses from peat bogs. These  
methods showed that temperatures in 
northern Europe dropped dramatically 
during the cold event. Lake sediments 
from north-western England show a 
decrease of 1.6°C lasting approximately 
160 years, while sphagnum moss from 
peat bogs in Newfoundland reveal 
similar cold conditions on the east coast 
of North America. 
Could it happen again?
Evidence from ocean records confirms 
the likely cause of the cold event is the 
catastrophic flooding of fresh water 
into the North Atlantic following the 
collapse of the North American ice sheet. The results verify 
that dramatic changes in ocean circulation can occur in short 
timescales and have major impacts on the climate of the North 
Atlantic region. 
The information obtained from the palaeo records has been 
used to assess whether computer models can correctly predict 
the influence of freshwater influx on the ocean conveyor and, 
ultimately, on climate. Models reflect the speed of change 
observed in the different environmental records but also show 
that even a relatively modest flow of fresh water can affect the 
ocean conveyor.
PhD student Tim Daly analysed the stable isotopes of oxygen and hydrogen in 
the cellulose of sphagnum moss taken from peat samples in Newfoundland. This 
highlights variations in source water and hence changes in climate and atmospheric 
circulation during the 8200-year event. 

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The Atlantic array
The first continuous Atlantic-
wide daily measuring system
Until 2007, scientists had no precise 
knowledge about the daily, weekly 
and monthly variability of the Atlantic 
Meridional Overturning Circulation, 
or Atlantic Heat Conveyor. But they 
know the circulation has been prone to 
sudden and dramatic shifts in the past.
In 2004, scientists installed the first array of scientific 
instruments across the Atlantic Ocean at latitude 26.5° North. 
Why 26.5°N?
This is where the overturning circulation is most vigorous. 
North of this latitude most of the heat is given off to the 
atmosphere where winds carry the heat north-eastwards 
towards Europe: one million million kiloWatts of heat are 
released to the atmosphere every second over the North 
Atlantic Ocean. Scientists wanted to measure the overturning 
circulation where it carries the maximum heat northwards, 
because long-term changes there can have a significant impact 
on Europe’s central heating system.
The first continuous, daily measurements of the Atlantic Meridional Overturning Circulation. (The strength of ocean currents is 
measured in Sverdrups (Sv), a million cubic metres per second.)

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Key findings and achievements
n	 The Atlantic array pilot scheme: it is now possible to make continuous, daily measurements of the strength 
and structure of the Atlantic Meridional Overturning Circulation or Atlantic Heat Conveyor. 
n	 The system made its first observations on 29 March 2004 and has been in continuous operation since then.
n	 The monitoring system has already significantly advanced knowledge of the North Atlantic circulation. 
‘Temporal variability of the Atlantic Meridional Overturning Circulation at 26.5°N’, Science, 317, 935-
38;‘Flow compensation associated with the Meridional Overturning Circulation at 26.5°N in the Atlantic’, 
Science, 317, 938-9 (August 2007). The journal Nature listed both papers in its top ten papers for 2007.
n	 The year-long average circulation from 29 March 2004 to 31 March 2005 is 18.7±5.6 Sverdrups (Sv)*. 
Interannual changes in the circulation can be monitored with a resolution of 1.5 Sv. 
n	 Three key components of the circulation (Gulf Stream, wind-driven surface circulation and transatlantic 
circulation) all contribute significantly to the variations in its strength. 
          *One Sverdrup = a million cubic metres per second.
Putting together part of the array system.

Measuring an ocean-wide circulation
The Atlantic Meridional Overturning Circulation is complex. 
There are three main components: the Gulf Stream, wind-
driven surface circulations and a large transatlantic circulation 
driven by heat and salinity. The new system measures all these 
components separately.  
Transatlantic circulation
An array of scientific instruments attached to 22 moorings 
measure depth, temperature, salinity and pressure on the 
continental slopes off the Bahamas, off Morocco and on 
either side of the mid-Atlantic Ridge. These are deployed and 
recovered annually and allow the team to continuously observe 
the strength and structure of the transatlantic circulation at 
26.5°N. 
At the western boundary, off the east coast of the US, the 
researchers, with US colleagues, directly measure the velocity 
of the deep, cold, southward-flowing currents using current 
meters attached to moorings. 
Wind-driven surface circulations
The near-surface waters of the ocean tend to move northwards 
at this latitude under the influence of trade winds and the 
Earth’s rotation. Continuous satellite wind measurements allow 
researchers to estimate these currents.
The Gulf Stream
In the Florida Straits, colleagues in the US measure the flow 
based on the way that sea water conducts electricity. As the 
Gulf Stream moves through the Earth’s magnetic field it induces 
variable electric currents in the telephone cable lying on the 
seabed from Florida to the Bahamas. The team can measure 
the currents and work out the total transport of the Gulf Stream 
on a daily basis. 
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The largest single investment in the Rapid 
Climate Change programme is an array of 
scientific instruments stretching across the 
Atlantic Ocean at latitude 26.5°N, from the 
west coast of Africa to Miami.

The sum of the parts
The instruments continuously monitor each of these 
components of the overturning circulation. Their sum gives, 
on a daily basis, the total strength and structure of the AMOC. 
Measurements started on the 29 March 2004 and will continue 
to 2014, giving a decade of observations.
Results
For the first time, scientists can say with confidence that 
the average strength of the AMOC from 29 March 2004 to 
31 March 2005 is 18.7 Sv. Three main circulations (the Gulf 
Stream, the transatlantic circulation and the wind-driven 
circulation in the upper ocean) contribute about equally to the 
AMOC’s variability of ±5.6 Sv. Over periods longer than about 
ten days the measured flow north and south at 26.5°N is found 
to balance (as expected from theory), confirming the validity of 
the monitoring system measurements. 
Why is this important?
The array has demonstrated that it is possible to make efficient 
and accurate measurements of a complex circulation on an 
ocean-wide scale. This is leading to new understanding of 
coupled ocean-atmosphere dynamics. In particular, the data are 
now being used to critically evaluate the realism of coupled 
climate models that predict future changes in the Atlantic 
circulation.
The system monitors interannual changes in the circulation 
with a resolution of 1.5 Sv. This means large, abrupt changes 
should be readily observed. Ten years of uninterrupted 
measurements will ensure that any seasonal cycles are well 
defined and help refine the nature of interannual variations, 
whether they are oscillations, trends or shifts.
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The North Atlantic and Arctic Oceans are critical 
components of the ocean-climate system. Warm 
tropical waters flow northwards, releasing 
heat to the North Atlantic region, and 
eventually flow into the Arctic 
Ocean. Cold waters sink in the 
northern North Atlantic and 
flow southwards forming the 
Atlantic Heat Conveyor.

The day after tomorrow
Modelling, prediction and forewarning
The value of the Rapid Climate Change programme 
is its role in improving the accuracy of climate 
models and providing forewarning of abrupt change. 
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Key outcomes
n	 Comparisons of climate models with palaeo data 
of past changes.
n	 Incorporating ocean data into models to better 
represent changes in the conveyor.
n	 Improved modelling of changes in the Greenland 
ice sheet.
n	 Quantifying the effect of changes in the Atlantic 
Heat Conveyor on weather systems reaching the 
UK.
n	 Intercomparison of rapid climate change 
processes in climate models of different levels 
of complexity. 
n	 New statistical tools to quantify risk and 
probability of rapid climate change.
Even with the best information on the current state of the 
climate system and using the best predictive computer models, 
scientists will struggle to accurately predict future climate. But, 
it is possible to test climate models’ abilities to reproduce past 
climate change and then assess the uncertainties surrounding 
their predictions of future rapid change. 
Scientists working on the Rapid Climate Change programme 
used a range of computer models to examine both past, 
present and future change. Although the main focus of the 
programme is on the role of the Atlantic Heat Conveyor, 
scientists also investigated important elements of the climate 
system in other parts of the world, such as changes in El Niño 
in the Pacific Ocean. 
El Niño 
El Niño is a naturally varying climate phenomenon in the 
Pacific which causes droughts and flooding in regions 
as far apart as Africa and India. Scientists know a major 
shift in El Niño occurred 6000 years ago. Researchers 
on the Rapid Climate Change programme studied this 
shift using coral records from the tropical Pacific and 
the Met Office Hadley Centre climate model. 
A model’s ability to reproduce both past and present 
climatic conditions gives researchers more confidence 
in its ability to predict the future. Scientists knew the 
model accurately reproduces 20th-century climate, but 
could it represent other climate states as well? 
The data obtained from the corals have shown that El Niño 
was considerably weaker 6000 years ago, though globally, the 
average climate of that period was broadly similar to today. 
The main difference is a variation in the seasonality of the orbit 
of the Earth around the sun. The model captures the qualitative 
aspects of the weakening of El Niño, although the magnitude 
of change in the model is less than that inferred from the coral 
work. This shows the importance of considering uncertainties 
in both the coral reconstructions of past climate and the model 
simulations to quantitatively assess the ability of models to 
simulate changes in climate.
Changes in the Atlantic Ocean – 
50-year reconstruction 
To put the new measurements of the Atlantic Heat Conveyor 
in context requires some knowledge of past changes. As 
Coring giant corals in the tropical Pacific to 
obtain records of past climate changes. 
University of Edinburgh.

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noted in the introduction, prior to the Rapid Climate Change 
programme, no continuous measurements of the conveyor 
existed. Evidence-based knowledge rested on five snapshots 
of the circulation taken over 50 years. To overcome this 
scarcity of direct measurements, the scientists worked with 
the European Centre for Medium Range Weather Forecasting 
to bring together all the ocean data on temperature and 
salinity acquired over the last 50 years and combined it with 
a computer model of the ocean. This allowed researchers to 
reconstruct the behaviour of the conveyor over that period. 
The results suggest that some slowdown could have occurred. 
They are now checking the results with improved models 
that can capture more details of the ocean circulation. Such 
a reconstruction can help understand recent changes and, by 
comparison with climate models, allow researchers to gauge 
the quality of those models and so their predictions of future 
change.
Modelling the Greenland ice sheet
Future changes in the input of fresh water into the North 
Atlantic might disrupt the Atlantic Heat Conveyor. The 
Greenland ice sheet is an important source for that fresh 
water. Therefore improved modelling of the behaviour of the 
ice sheet is necessary to make better predictions of future 
changes in melting. This requires more detailed models of the 
Greenland ice sheet on a regional scale. The Rapid Climate 
Change programme has developed such improved models. 
These models show good agreement with the observed rate of 
melting. 
Changes to storm tracks reaching the UK
People in the United Kingdom are less concerned with 
what the Atlantic Heat Conveyor is doing per se than with 
how changes in the conveyor will affect weather and 
climate. Using climate models, researchers have looked at 
the response of the storms tracking across the Atlantic to 
changes in the strength of the conveyor. The initial results 
suggest that, as the conveyor slows, more storms occur and 
tend to track farther north, penetrating deeper into Europe. 
The exact behaviour predicted varies with how much detail 
the model can capture, for example, in the detailed pattern 
of the North Atlantic sea-surface temperature, which 
affects the atmosphere above it and so the behaviour of 
storms tracking across the ocean. Such detail is a function 
of the computer power available – the more detailed the 
model, the more computer power is required to run it.
Future surface air temperature increases due to global warming. Note that the slowdown of the ocean conveyor leads to less 
warming in the North Atlantic region. Max-Planck Institute for Meteorology, Hamburg climate model. The institute is a partner in the 
Rapid Climate Change programme (IPCC Scenario AIB).

Risk and probability of a slowdown
In 2007, the UN’s Intergovernmental Panel on Climate Change 
(IPCC) Fourth Assessment Report concluded that it is very likely 
that the Atlantic Ocean conveyor will slow down during the 
21st century. The IPCC models show a range of 0-50 per cent 
reduction, and an average reduction across the models of 25 
percent by the end of the century. To determine the source 
of this uncertainty, Rapid Climate Change researchers are 
comparing models of different levels of complexity. 
Running a computer climate model is a costly business, 
especially as they become better at resembling the real world. 
These complex models put immense pressure on computing 
resources, particularly if the models need to run hundreds 
or thousands of times in order to work out probabilities of 
an event occurring. Pioneering work by scientists on the 
programme has led to powerful statistical tools that allow 
approximations of a climate model to run many times extremely 
quickly. This provides a very efficient route to getting a large 
set of results from which to calculate probabilities. These 
tools are known in the trade as emulators. Application of 
emulators extend beyond climate science to any modelling 
problem that involves a wide set of starting conditions that you 
might want to change. The tools hold particular benefits for 
price modelling, for example, calculating the cost to insurers 
of extreme weather events. The programme’s researchers 
are already talking to the financial services sector about 
future collaborations. What is clear is that a slowdown of the 
conveyor will have a regional climatic impact and that the 
scale of that impact depends on the magnitude and rate of the 
slowdown. Despite the progress made, challenges remain. 
Not least whether researchers can improve climate forecasts 
on shorter (decadal) timescales. This is a major challenge 
for Rapid-WATCH, the follow-on phase of the Rapid Climate 
Change programme. It is also central to the NERC strategy Next 
Generation Science for Planet Earth, which seeks to develop 
risk-based predictions of the future state of the climate on 
regional and local scales, spanning days to decades. 
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Greenland ice sheet melting 
determined using a regional 
climate model. The results 
shown are for 1989. The 
model is able to reproduce the 
observed melting rates (in units 
of mm water equivalent). 
Utrecht University

Knowledge Exchange
Working with stakeholders
Findings from the Rapid Climate Change 
programme are nationally and internationally 
significant, both to the scientific community 
and policy-makers. The Rapid Climate Change 
programme has a responsibility to ensure key 
scientific findings are effectively communicated 
to the user community. 
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As UK policy-makers plan and implement strategies to increase 
resilience to the changing climate, it is important the scientific 
community advise of the risks associated with abrupt climate 
change. It is also important that policy-makers and other 
stakeholders are involved in planning of research at an early 
stage to ensure research programmes deliver the information 
policy-makers require in a format they can use. Since 2003, 
the Rapid Climate Change programme has had an active 
knowledge exchange strategy to meet these goals.
The Rapid Climate Change programme has pro-actively 
contacted key UK organisations and decision makers who 
stand to benefit from the programme’s research. The key 
stakeholders include the United Kingdom Climate Impacts 
Programme (UKCIP) and the Marine Climate Change Impacts 
Partnership (MCCIP), led by the Department for Environment, 
Food and Rural Affairs (Defra). The make-up of the stakeholder 
community, assembled over the programme’s life, reflects our 
desire to interact with both central and devolved government 
departments and agencies to help inform both national and 
regional issues. 
The team has carefully considered how best to communicate 
the key results, taking into account contributions to major 
reports, their own briefing material and maximising the value of 
face-to-face briefings and dedicated stakeholder presentations. 
For a large number of stakeholders, the first port of call for 
expert advice on climate change impacts remains UKCIP. The 
Rapid Climate Change team works closely with UKCIP to 
maintain a series of guidance notes on the Atlantic conveyor. 
These summarise present knowledge and highlight recent 
findings. The team has also contributed to the Atlantic 
conveyor section of the UKCIP2008 Climate Scenario reports.
The programme is a founding scientific partner of the Defra-
led MCCIP – a new initiative uniting scientists, government 
agencies and non-governmental organisations to provide 
advice on climate change impacts within UK and adjacent 
waters. A key product of the MCCIP initiative is the Annual 
Report Card summarising major advances within the scientific 
field. The Rapid Climate Change programme has played an 
active role in the 2005-06 and 2006-07 reports.
The Rapid Climate Change programme has also focused 
significant resources on consolidating its understanding of 
The Rapid Climate Change user 
community
The programme has been successful in forging 
relationships with a broad spectrum of UK climate- 
change stakeholders including:
n	 Defra
n	 The Welsh Assembly 
n	 The Scottish Government
n	 Willis Analytics
n	 Natural England
n	 The Scottish Environmental Protection Agency
n	 The Environment Agency
n	 The Parliamentary Office of Science and Technology
n	 The World Wide Fund For Nature
Martin Mlecko
©iStockphoto.com/George Cairns

20
R A P I D  C L I M AT E  C H A N G E
how climate science is used by stakeholders, particularly 
informing policy. The programme’s steering group contains a 
representative from Defra. These steps have been augmented 
by personnel secondments from the programme to Defra’s 
offices in the past two years. All of these initiatives have 
proved invaluable in expanding the team’s knowledge of 
government operation and how best to tailor knowledge- 
exchange activities to meet demand. One direct change 
implemented as a result of such secondments has been to 
provide Defra (and other stakeholders) with manuscripts of all 
policy-relevant publications from the programme accompanied 
by summary briefing notes. These are especially useful in 
aiding Defra officials to prepare ministerial briefings and in 
updating knowledge-bank entries which aid the policy-forming 
process.
The team has also built relationships with the financial and 
private sectors, especially where exposures to abrupt climate 
change are evident. These sectors are particularly interested 
in the programme’s emulator technology, which can produce 
probabilities of events occurring, where chances can be 
influenced by a large number of variable parameters. The 
programme developed these emulator technologies to test 
the sensitivity of the Atlantic Heat Conveyor to a collapse as a 
result of global warming. But these powerful tools have wider 
applications. The Rapid Climate Change team is currently 
exploring the possibility of working alongside reinsurers to 
develop applications for use in catastrophe risk pricing. 
Rapid WATCH 
The Rapid Climate Change core team continue to identify new 
stakeholders across the private and public sectors and looks 
forward to making even further progress during the transition 
between the Rapid Climate Change programme and its 
successor, Rapid WATCH, which runs to 2014.
Rapid Climage Change data
Two NERC data centres, the British Atmospheric Data Centre 
and the British Oceanographic Data Centre, store and distribute 
data from the programme. www.bodc.ac.uk/projects/uk/rapid/

21
P A S T   P R E S E N T   F U T U R E
The Marine Climate Change Impacts 
Partnership (MCCIP)
MCCIP is a Defra-led partnership between marine 
stakeholders, the UK government and the scientific 
community, providing advice on climate change and 
its impacts. 
The partnership produces an annual report card 
summarising the physical climate change under 
way in UK and adjacent waters, recent findings 
concerning impacts, and knowledge on future 
change. The report is circulated to all UK MPs and 
the stakeholder community.
As a founding partner, the Rapid Climate Change 
programme provides scientific expertise and is 
represented on the MCCIP steering committee.
The 2007-08 MCCIP Annual Report provides detailed 
information on a number of topics including:
n	 regional changes in sea surface and air 
temperature;
n	 observed and future changes to the Atlantic 
conveyor, including the first year’s observations 
from the 26°N array of scientific instruments;
n	 ocean acidification;
n	 regional coastal erosion.
The full report and supporting information is 
available online: www.mccip.org.uk
The UK Climate Impacts Partnership 
(UKCIP)
Established in 1992, UKCIP plays an integral role 
connecting stakeholders with the latest scientific 
findings and scenarios of future climate change.
The partnership provides detailed advice to help 
users adapt and increase resilience to climate 
change risk.
Risks from abrupt climate change, relating to the 
Atlantic Heat Conveyor, are a frequent source of 
concern. The Rapid Climate Change programme 
assists UKCIP to maintain user guidance notes, 
summarising the present level of understanding of 
these risks, and assessing the likelihood of future 
change.   
In 2008, UKCIP release the latest suite of climate- 
change scenarios for the 21st century. For the first 
time, gridded, probabilistic information on key 
climatic variables will be accessible via a web 
portal. Three written reports accompany these data: 
n	 the climate of the United Kingdom and recent 
trends;
n	 future terrestrial scenarios; 
n	 future marine scenarios.
Researchers on the Rapid Climate Change 
programme have co-authored a section on the 
Atlantic conveyor summarising recent observations 
from the programme, and additional sources, and 
projections of future changes. 
©iStockphoto.com/Lyle Gregg

22
R A P I D  C L I M AT E  C H A N G E
Media and the public 
In 2007, climate change entered the media mainstream. 
With this came passionate debate about how to present 
the complex and contradictory ideas inherent in the Rapid 
Climate Change programme to a wider audience. But 
public interest in the programme really took off in 2004 
with the release of the Hollywood blockbuster The Day 
After Tomorrow. This media attention continues to this 
day, fuelled by regular releases of new results. It reached 
a highpoint in December 2005 when the science journal 
Nature published results which suggested a marked 
slowdown of the Atlantic conveyor over the last 50 years. 
A deluge of interview requests flowed in from around the 
world. Photos, figures, quotes and misquotes from the 
programme found their way into radio, TV, newspapers, 
magazines and websites too numerous to count. 
The Nature paper, based on sporadic and infrequent 
measurements stretching back over five decades highlighted 
Outreach
Information, 
education, inspiration
Will the possibility of a 
cooler Europe confuse 
people when what society 
needs is clear facts so it can 
take firm action? The Rapid 
Climate Change programme 
has ignited fierce debate 
among scientists and 
environmentalists. It has 
also inspired art, informed 
education and captured the 
imagination of the media and 
public alike. 
the urgent need for continuous measurements to understand 
the natural variability of the Atlantic Heat Conveyor. 
A second peak in media attention followed nearly two 
years later, coinciding with the publication of the first 
year-long results from the Atlantic array. These landmark 
results were published in two back-to-back papers in 
the American journal Science on 17 August 2007. 
Scientists from the programme have done their best to 
temper sensationalism without giving the impression 
that there is absolutely no need for concern. This is 
not always easy. The Atlantic Heat Conveyor and its 
effect on European climate cannot fit into a 30-second 
soundbite any more than a slowdown of the circulation 
can be confirmed by a few days of zero flow. 
Art, education and climate change
The programme has encouraged and attracted innovative 
Amy Balkin/Cape Farewell

23
P A S T   P R E S E N T   F U T U R E
Key outcomes
n	 The programme has attracted significant 
and sustained media interest, nationally and 
internationally.
n	 Working with artists and writers, the programme 
has increased public awareness of the role 
played by the ocean in the global climate 
system.
n	 Information about rapid climate change is now 
included in the curriculum for UK schools.
approaches to outreach and communication. From the outset, 
it has had the support of professional artists and writers. 
American science writer Dallas Murphy took part in an early 
science expedition, an experience that features prominently 
in his book Follow the Water. German photographer Martin 
Mlecko crewed on a recent voyage to the array at 26º North. 
His photos now feature both in exhibitions and online. 
In the UK, the Rapid Climate Change programme has had 
a long and fruitful collaboration with Cape Farewell – a 
group of artists, writers, scientists and educators led by 
photographer David Buckland. This has brought the ‘art 
of climate change’ into science conferences through art 
exhibitions and after-dinner talks, and the science of climate 
change into numerous touring exhibitions, a variety of TV and 
radio programmes, books, articles, news coverage, and public 
panel debates. The programme has lent scientific support 
to Cape Farewell’s work and expeditions – most recently 
the 2007 Youth Expedition. Through Cape Farewell, the 
‘Ice Texts’ by artist and film-maker David 
Buckland draw attention to the peril of 
melting Arctic ice.
programme has contributed to GCSE teaching material which 
looks set to form part of the new UK science curriculum.
Cape Farewell’s 2007 Youth Expedition took 
12 students from UK, Germany and Canada 
to the Arctic to join science projects. 
Dan Harvey/Cape Farewell
David Buckland/Cape Farewell

24
R A P I D  C L I M AT E  C H A N G E
Rapid WATCH 
(2008-14)
Will the Atlantic 
Thermohaline 
Circulation Halt? 
From pilot scheme to decadal 
measuring system.
The flagship of the Rapid Climate Change programme, 
a pilot scheme to measure the Atlantic Meridional 
Overturning Circulation, has been a success. This is a major 
achievement which the American journal Science has 
described as a ‘bold initiative’. The Natural Environment 
Research Council has committed a further £16.1 million 
to complete a full decade of observations, up to 2014. 
This follow-on programme is called Rapid WATCH 
(Will the Atlantic Thermohaline Circulation Halt?).
The measurements will be used with other observations 
of the North Atlantic and computer models to determine 
the state of the ocean circulation, and to improve 
predictions of future changes. This next phase of research 
will involve scientists from Canada, Germany and the 
USA. Close collaboration with the Met Office Hadley 
Centre will allow results from the programme to feed 
into the centre’s decadal prediction system. This will 
lead to improved climate prediction, both globally and 
in particular for the UK and north-west Europe, where 
the impact of changes in the conveyor are largest.
The Natural Environment Research Council’s initiative has 
led to other major projects: the European Union has funded 
THOR (ThermoHaline Overturning – at Risk?); and in the 
US, scientists are developing a programme to improve 
modelling and prediction, and to make measurements further 
north and south in the Atlantic. These initiatives provide 
opportunities for further international collaboration.
In this next phase the observations and modelling will 
become the basis of a major decision: should the observing 
system move from research to operational status beyond 
2014? The decision will be based on an assessment of the 
scientific and, in broad terms, socio-economic benefits of 
an operational-monitoring system for the Atlantic conveyor.  
This will include an estimate of the timescale on which 
the full benefits of such a system would be realised.

25
P A S T   P R E S E N T   F U T U R E
‘I recognise that major steps like the Rapid 
Climate Change programme are critical to 
improving our understanding and prediction of 
climate. These major steps take considerable 
courage and foresight by both scientists and their 
funders. The leadership shown by NERC is critical 
to realising these improvements.’
John Church, Chair of the Joint Scientific Committee of 
the World Climate Research Programme, 2007.

26
R A P I D  C L I M AT E  C H A N G E
Principal Investigator	
Institute	
Title
Professor H. Bryden/	
National Oceanography	
Monitoring the Atlantic Meridional Overturning 	
Dr S. Cunningham 	
Centre, Southampton	
Circulation at 26.5°N
(previously 
Professor J. Marotzke)
xxx@xxx.xx
xxx@xxx.xx
Professor A. Watson	
University of East Anglia	
Time series of transient tracers in North Atlantic 
xxx@xxx.xx 	
	
deep waters
Professor C. Hughes	
Proudman Oceanographic	
A monitoring array along the western margin of
xxx@xxx.xx	
Laboratory	
the Atlantic
Dr D. Cromwell	
National Oceanography	
Measuring the Meridional Overturning Circulation
xxx@xxx.xx	
Centre, Southampton	
from space: a feasibility study
From MOC Observing System Announcement of Opportunity (jointly with NSF)
Principal Investigator	
Institute	
Title
Professor A. Willmott	
Proudman Oceanographic 	
Processes controlling dense water formation and
xxx@xxx.xx	
Laboratory	
transport on Arctic continental shelves
Dr S. Josey	
National Oceanography	
The role of air-sea forcing in causing rapid
xxx@xxx.xx	
Centre, Southampton	
changes in the North Atlantic Thermohaline 	
	
	
Circulation
Dr E. Wolff	
British Antarctic Survey	
High resolution anatomy of rapid climate
xxx@xxx.xx	
	
transitions in the last glacial period from a 	
	
	
Greenland ice core
Professor I. N. McCave	
Cambridge University	
Hydrographic and flow changes at sharp climate
xxx@xxx.xx	
	
transitions in the North Atlantic MOC, 0-16ka BP
Professor R. Williams	
Liverpool University	
The role of sloping topography in the overturning
xxx@xxx.xx	
	
circulation of the North Atlantic
Professor K. Briffa	
University of East Anglia	
Quantitative applications of high-resolution late
xxx@xxx.xx	
	
Holocene proxy data sets: estimating climate 	
	
	
sensitivity and thermohaline circulation 	 	
	
	
influences
Projects and contacts

27
P A S T   P R E S E N T   F U T U R E
Principal Investigator	
Institute	
Title
Professor B. Hoskins	
Reading University	
The atmospheric water vapour budget and
xxx@xxx.xx	
	
its relevance to the THC
Dr E. Guilyardi	
Reading University	
The role of salinity in ocean circulation and
xxx@xxx.xx	
	
climate response to greenhouse gas forcing
Professor A. Tudhope	
Edinburgh University	
Improving our ability to predict rapid changes in
xxx@xxx.xx	
	
the El Niño Southern Oscillation 	
	
	
	
climatic phenomenon
Professor A. Watson	
University of East Anglia	
Circulation, overflow, and deep convection 	
xxx@xxx.xx	
	
studies in the Nordic Seas using tracers and 	
	
	
models
Professor I. Fairchild	
University of Birmingham	
Atlantic Seaboard Climate Responses including
xxx@xxx.xx	
	
Bounding Errors (ASCRIBE)
Professor H. Bryden	
University of Southampton	
Extending the time series of Atlantic Meridional
xxx@xxx.xx	
	
Overturning backwards in time using historical 	
	
	
measurements
Mr P. Challenor	
National Oceanography	
The probability of rapid climate change
xxx@xxx.xx	
Centre, Southampton	
Dr S. Bacon	
National Oceanography 	
Cape Farewell and Eirik Ridge: interannual  to
xxx@xxx.xx	
Centre, Southampton	
millennial thermohaline circulation variability
Dr N. Wells	
University of Southampton	
The determination of heat transfer and storage,
xxx@xxx.xx	
	
and their changes in the North Atlantic Ocean
Professor C. Pain	
Imperial College, London	
Better understanding of Open Ocean Deep
xxx@xxx.xx 	
	
Convection (OODC) with reference to THC 
Dr J. Holmes	
University College, London	
ISOMAP UK: a combined data-modelling
xxx@xxx.xx	
	
investigation of water isotopes and their 		
	
	
interpretation during rapid climate change events
Professor J. Bamber 	
University of Bristol	
The role of the cryosphere on modulating the
xxx@xxx.xx	
	
thermohaline circulation of the North Atlantic
From 1st Announcement of Opportunity

 Principal Investigator	
Institute	
Title
Dr William E.N. Austin	
University of St Andrews	
Can Younger Dryas atmospheric 14C concentration
xxx@xxx.xx	
	
be attributed to North Atlantic surface ocean 	
	
	
ventilation?
Dr Sheldon Bacon 	
National Oceanography	
Arctic Regulation of Thermohaline Circulation
xxx@xxx.xx	
Centre, Southampton 	
(ARTHER) 
Dr Mark R. Chapman	
University of East Anglia	
Multi-decadal variability through the early and
xxx@xxx.xx	
	
late Holocene in the subpolar North Atlantic
Professor Jonathan Gregory	
National Centre for	
Understanding uncertainty in simulations of THC-
xxx@xxx.xx	
Atmospheric Science, 	
related rapid climate change
	
Reading 
Professor Jonathan Gregory	
National Centre for	
UK coupled model intercomparison project on the
xxx@xxx.xx	
Atmospheric Science,  	
thermohaline circulation
	
Reading 	
Professor Keith Haines	
Environmental Systems	
Assimilation in ocean and coupled models to
xxx@xxx.xx 	
Science Centre, Reading 	
determine the thermohaline circulation
Professor Brian J. Hoskins	
Reading University	
The impact of climate change on North Atlantic
xxx@xxx.xx 	
	
and European climate regimes
Professor John Lowe 	
Royal Holloway, 	
A precise chronology for establishing the timing
xxx@xxx.xx 	
of London University 	
changes in North Atlantic thermohaline 
	
	
circulation (THC), and its climatic consequences,
	
	
16-8 cal ka BP
Professor David Marshall	
Oxford University	
Attribution of ocean climate change signals in the
xxx@xxx.xx 	
	
Atlantic
Professor Rowan Sutton 	
Reading University	
Probabilistic forecasting of the Atlantic
xxx@xxx.xx	
	
Meridional Overturning Circulation and 	 	
	
	
associated rapid climate change
	
	
	
	
	
Professor Andy Watson 	
University of East Anglia	
Time Series of Transient Tracers (TESTT)
xxx@xxx.xx	
From 2nd Announcement of Opportunity
 
28
R A P I D  C L I M AT E  C H A N G E

Principal Investigator	
Institute	
Title
Professor Grant R. Bigg	
University of Sheffield	
Punctuated disintegration of the NW European 
ice xxx@xxx.xx	 	
sheet and rapid climate change 
Professor Henry Elderfield	
University of Cambridge	
Variations of the Atlantic MOC during rapid
xxx@xxx.xx	
	
changes: calibration, modelling and 	
	
	
	
palaeoceanographic observations (VAMOC)
Professor Sandy Harrison 	
University of Bristol	
Impact of changing freshwater flows on the THC
xxx@xxx.xx	 	
and European climate 
Dr Timothy J. Osborn 	
University of East Anglia	
To what extent was the Little Ice Age a result of a
xxx@xxx.xx	
	
change in the THC? 
Dr M.R. van den Broeke 	
Institute for Marine and	
Mass balance and freshwater contribution of the
xxx@xxx.xx	
Atmospheric Research, 	
Greenland ice sheet: a combined modelling and
	
Utrecht University	
observational approach
From Joint International RCN/NWO/NERC Announcement of Opportunity
P A S T   P R E S E N T   F U T U R E
29
P A S T   P R E S E N T   F U T U R E

Natural Environment Research Council
Polaris House, North Star Avenue
Swindon, SN2 1EU, Wiltshire
Tel: xx-xxxx-xxxx
www.nerc.ac.uk
The Natural Environment Research Council (NERC) uses an annual 
budget of £400 million to fund independent environmental research in 
the United Kingdom. The priorities we develop with our researchers 
and stakeholders provide a focus for the marine, polar, atmospheric, 
earth, terrestrial and freshwater science communities. 
The research is often multidisciplinary and in collaboration with other 
national and international partners. NERC runs a fleet of research 
ships and scientific aircraft. We have bases in some of the world’s 
most hostile environments and invest in satellite technology to 
monitor environmental change on a global scale. 
NERC’s research and collaborative centres maintain and develop UK 
national capability across the disciplines that make up environmental 
science. We fund centres and universities to carry out research 
and to train and support a world-class community of environmental 
scientists. 
In 2001, NERC set up the £20 million Rapid Climate Change 
programme to investigate the fundamental processes that cause 
climate to change abruptly. 
Rapid Climate Change programme
www.nerc.ac.uk/research/programmes/rapid/