What is the point of this session?• To use the UK’s experience to give

ideas about creating and using climate change scenarios in other countries and situations

• Not a talk on climate modelling!• An overview of who, how, what and

why• Discussion of how these experiences

apply to your own needs

The next hour and a half…..• What are climate change scenarios and how

have they featured in the UK?• How have the “UKCIP02” scenarios been

created?• Who are the major players?• How have we dealt with uncertainties?• Potential applications of the UKCIP02 scenarios• How can the scenarios be improved?• Lessons for the future• Discussion

What are scenarios?

A scenario is: “a coherent, internally consistent and

plausible description of a possible future state of the world” (Parry and

Carter, 1998)

Not a forecast or a prediction A series of pictures of what the world

could look like in the future

Climate change scenarios• Socio-economic futures (eg.

population, economy, carbon intensity) - affects how GHG may change

• Climate modelling• Result: integrated scenarios -

more sophisticated than pure climate modelling

A history of UK Climate Change scenarios• Climate Change Impacts Review

Group of the DoE (CCIRG)• 1991, 1996• Presented a range of highly artificial

global-scale scenarios (CO2 doubling)

• Tended to present a ‘best guess’ based on 1980s Met Office UKTR model and HadCM1

The 1998 UKCIP scenarios• 1997: UK Climate Impacts Programme

(UKCIP)• 1998: Climatic Research Unit, Hadley

Centre created UKCIP98 scenarios• Wider range of variables and time-scales

than CCIRG• Range of four scenarios based on

IS92a/IS92d• HadCM2 model

How have the UKCIP02 scenarios been created?

UKCIP02 Climate Change Scenarios

• Mike Hulme• Xianfu Lu• John Turnpenny• Tim Mitchell

• Geoff Jenkins• Richard Jones• Jason Lowe• James Murphy• David Hassell• Penny Boorman• Ruth McDonald• Steven Hill

UKCIP02 Climate Change Scenarios

• Funded by:

• For:

The UKCIP02 Scenarios

• To be launched April 2002 • Revised scenarios using developments

over past three years• Explicitly linked to four socio-economic

scenarios produced by IPCC• Informed by the Third IPCC Climate

Change Assessment Report

• Uses more sophisticated HadCM3 and regional HadRM3 models (more greenhouse gas species, improved ocean and vegetation models)

• Much more detailed regional information (104 vs. 4 grid boxes)

• 5 km observed data set• Responses to users: much more on

extremes; rapid climate change; Gulf Stream; uncertainty

The SRES Scenarios

Storyline Description

A1 Very rapid economic growth; population peaks mid-century; social, cultural andeconomic convergence among regions; market mechanisms dominate. Subdivisions:A1FI – reliance on fossil fuels; A1T – reliance on non-fossil fuels; A1B – a balance

across all fuel sources A2 Self-reliance; preservation of local identities; continuously increasing population;

economic growth on regional scales B1 Clean and efficient technologies; reduction in material use; global solutions to

economic, social and environmental sustainability; improved equity; population peaksmid-century

B2 Local solutions to sustainability; continuously increasing population at a lower ratethan in A2; less rapid technological change than in B1 and A1

Global carbon emissions - four IPCC scenarios (2000 - 2100)

Carbon dioxide concentrations: IPCC scenarios

The four UKCIP02 scenarios• High Emissions A1FI• Medium-High Emissions A2• Medium-Low Emissions B2• Low Emissions B1

as inputs to Hadley Centre’s HadCM3 model (effective sensitivity 3.0 deg C)

Global temperature (2000 - 2100)

The Hadley Centre Global Climate Model (HadCM3)

19 levels in

atmosphere

20 levels

in ocean

2.5lat 3.75

long

1.25 km

1.25 km

300 km

-5km

Hadley Centre Regional Climate Model (HadRM3)

50 km grid

What are UKCIP02’s defining characteristics?• It was GENERIC rather than for a

SPECIFIC impacts project• The centre of a policy network of

groups with different aims• Scenario range examined

emissions uncertainty rather than uncertainty in the model

What do the key players represent?• DEFRA - funder; government policy;

international obligations; public perception

• UKCIP - scenario users (scientists, policymakers, impact assessments)

• Hadley - rigorous science basis of climate modelling

• Tyndall - leading the analysis and writing; coordinating report production

The results

• UKCIP02 had to balance needs of all the organisations

• Ease of communication vs. rigorous science vs. usefulness to impacts community

• Example - pattern-scaling

Pattern-scaling

• Only A2 emissions, 2071-2100 means were modelled

• Other time periods and emissions scenarios were produced by ‘scaling’ the model output patterns

• Scientifically less than rigorous• But needed by the users (eg 2020s,

2050s)

Interaction with other groups

• Hadley Centre modellers - storm surges/ocean modelling

• Land movement (Durham)• Sea level (POL)

What will happen to sea level?

Sea level change: Four IPCC scenarios

Components of sea-level rise in 21st century

Commitment to sea-level rise: 600 + years

UK land movement (mm/yr) [Source: Ian Shennan]

How have we dealt with uncertainties?

What uncertainties are there?• Emissions - how will society change?

We chose to explicitly include these in the range of scenarios

• Scientific - how do different models represent the environment? We have assessed the main scientific uncertainties and provided guidance on how to incorporate these

UK temperature and precipitation (2080s) comparison of models

Winter temperature change with C-cycle (2080s, Medium-High Emissions)

Summer temperature change with C-cycle (2080s, Medium-High Emissions)

Methane concentrations - with and without climate change feedbacks (A2 Emissions)

Ozone concentrations - with and without climate change feedbacks (A2 Emissions)

Pattern-scaling

• Scientifically acceptable to scale HadRM3 patterns with other models’ global temperatures? We decided not.

• Acceptable comparison between model and pattern-scaled results? Yes.

HadRM2 vs. HadRM3Mean temperature change

HadRM2 vs. HadRM3Precipitation change

Daily maximum temperature: HadRM3 (dotted) vs. observations (solid)

Potential applications of the UKCIP02 scenarios

• Impacts, Adaptation, Vulnerability

• Informing Mitigation Policy

• Education and communication

Stakeholder Decision Scenario Requirements UKCIP StudyCountryside andconservationmanagers

Evaluating and managing achanging naturalenvironment

Guided sensitivity analysiscombining historical variationsin climate with future changes inclimate under a range ofscenarios

MONARCH

Regional land useplanners

How to assess relativevulnerability and plan forchange across differentsectors

Regional scenarios with a widerange of climate outputs

Sub-UK andregionalassessments

Regional coastaland flood defencemanagers

Developing a riskassessment for a coastal“cell” or river catchment

Geographically explicitscenarios, showing thelikelihood of changes in extremeweather events

RegIS

Water resourcemanagers

Evaluation of the futurewater supply/demandbalance and whether to planfor new resources

Regional scenarios with explicitprobability assessment; returnperiod of extreme weather events

CD:DEW

Lessons for the future

Questions for discussion• Who are your scenarios for?• Who is funding them?• How will they link climate and social science?• Who is the most important player?• How might the different powers interact?• How will you communicate them to relevant

groups and to the public?• Are they ‘user-friendly’?• Which government department is responsible, if

any?