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Arc Manche Conference
Climate Scenarios UK Climate Impacts
Programme December 3rd 2008
Dr Alastair Brown, UKCIP
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Overview

• UK Climate Impacts Programme (UKCIP) some
  terminology
• Summary of what we might expect based on current
  model projections
• UKCIP02 (UK Bias)
• Introduction to new climate model information
  (UKCIP08)
• Principles which underlie UKCIP08
• Probabilistic climate projections
• UKCIP08 Products

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Introduction
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UKCIP

• Set up by UK Government in 1997
• Funded by Defra based at Environmental Change
  Institute, University of Oxford
• UK Climate Impacts Programme (UKCIP)
• helps organisations to assess how they might be
  affected by climate change, so that they can
  prepare for its impacts
• Focus on adaptation, given necessity of
  mitigation

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UKCIP ToolsAll available from the UKCIP web site
at no charge
The Brain
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Terminology - Uncertainty

• Does not mean that we do not know whether there
  will be climate change
• Does mean that we do not know exactly how much
  climate change there will be in a certain place
  by a certain time
• Can be measured by the level of agreement
  between different climate scientists / models

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Terminology Weather vs. Climate

• Climate is what you expect, weather is what you
  get
• Robert Heinlein, Time Enough for Love
• Weather is the conditions on any given day
• Climate is the total experience of weather over a
  longer period of time (conventionally 30 years)
  i.e. averages, records
• It is impossible to say what the weather will be
  like on this day next year
• It is possible to describe what a typical June
  day is like (based on our experience of many June
  days.)

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Climate projections
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Stages in climate modelling
Scenarios from population, energy, economics
models Carbon cycle and chemistry models Gas
properties Coupled climate models Impacts
models
EMISSIONS
CONCENTRATIONS CO2, methane, etc.
HEATING EFFECT Climate Forcing.
feedbacks
CLIMATE CHANGE Temp, rain, sea level, etc.
IMPACTS Flooding, food supply, etc.
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Climate projections based on UKCIP02

• Changes in annual / seasonal averages
• hotter, drier summers
• milder, wetter winters
• rising sea levels
• Changes in extremes (both frequency and
  intensity)
• more very hot days
• more intense downpours of rain
• shorter return periods for high water levels at
  coast
• This level of understanding is enough for many
  decision types

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Change in annual mean sea surface temperature
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Climate projections What's next
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UKCIP08 principles

• UKCIP08 based on three important principles
• Examination of the uncertainty associated with
  the Met Office Hadley Centre climate model
• Assessment of the quality of model version
  results from the Hadley Centre climate model
• Incorporation of results from other climate models

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Modelling uncertainty UKCIP08
Size of change

• 31 parameter values
• 300 versions of the Hadley Centre climate model

Time
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Parameterisation

• Low clouds cool climate
• High clouds warm climate

Many important processes take place at a scale
smaller than the grid size of the model. These
are termed subgrid-scale processes. These cannot
be described explicitly and so must be estimated
from grid scale variables such as wind,
temperature etc this is termed parameterisation
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Modelling uncertainty UKCIP08
Size of change
Time
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Modelling uncertainty - many model versions

• We can group the number of models that project a
  certain size of change
• Tells us nothing about how good each model
  version is

Frequency
Count
Size of change
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Assessing model quality

• The only way we have of assessing the quality of
  climate models is to see how well they simulate
  observed climate
• It is assumed that models which are better at
  representing past climate will be better at
  representing future climate

Size of change
Time
Recent climate (1961-90)
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Modelling uncertainty estimating PDFs

• The importance given to each model version is
  altered based on how well they represent current
  climate and recent trends
• This can be used to estimate a Probability
  Distribution Function (PDF)

Count
Probability
PDF of Hadley Centre model results
Size of change
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Modelling uncertainties different models give
different results
Size of change
Time
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Modelling uncertainty PDFs are modified to
incorporate single runs of other IPCC models
Probability
UKCIP08 probabilistic climate projection
Size of change
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UKCIP08 Principals Summary

• Previous scenarios said
• there will be this much change
• UKCIP08 will say
• based on our current understanding, there is __
  probability there will be this much change

Amount of projected change
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How will UKCIP08 be provided to users?
Marine projections Information on modelled future
changes above and below the surface of sea areas
around the UK
Probabilistic climate projections Information on
modelled future climate change, provided in
probabilistic terms
Historical climate information Information on
present UK climate and recent trends, based on
observations
Key findings
Published material
Customisable output
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How will UKCIP08 be provided to users?
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Thank You alastair.brown_at_ukcip.org.uk www.ukcip.or
g.uk