Climate Scenarios in Vulnerability, Impact and Adaptation Assessments:

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Climate Scenarios in Vulnerability, Impact and
Adaptation Assessments MAGICC/SCENGEN overview
AIACC Scenarios Training Course Norwich, 16-25
April 2002 Dr Mike Hulme
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MAGICC/SCENGEN 2.4, IPCC SAR Version

• Observed data four regions 0.5deg resolution
• IS92 emissions, plus preliminary SRES emissions
• 14 GCM patterns, with/without aerosols
• IPCC Second Assessment version of MAGICC
• Changes in average monthly/seasonal climate

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MAGICC/SCENGEN 3.0, IPCC TAR Version

• Observed data all land areas 10 resolution
• Final (35) SRES emissions scenarios
• SRES-forced GCM patterns, with aerosols
• IPCC Third Assessment version of MAGICC (Sarah
  Raper)
• Changes in interannual variance as well as means
• Diagnostic tools (scatter plots) to explore
  uncertainty for user regions

Whats the difference? 100,000 which we are
seeking!
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Purpose of MAGICC/SCENGEN

• MAGICC
• Consistent scenarios of global CO2, T and SL
• Linked to IPCC emissions and IPCC science

• SCENGEN
• Exploratory tool regarding regional climate
  response patterns
• Allows a wide range of uncertainties to be
  quantified
• Enables generation of 1st order regional climate
  scenarios
• Combines GCM changes with observed climate fields

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Pattern-scaling

• Step 1 Define master pattern from GCM in such a
  way as to maximise signal/noise ratio
• e.g. 2071-2100 mean temperature minus 1961-1990
  mean temperature (from an ensemble of n
  simulations)
• e.g. fit a linear regression through 1961-2100
  time series data

Key assumption anthropogenic climate change
signal can be adequately defined from climate
models
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Pattern-scaling

• Step 2 Normalise the master pattern to 1C global
  warming

Key assumption the anthropogenic climate change
patterns are a function of global temperature
Step 3 Re-scale the normalised master pattern by
the global warming of the relevant emissions
scenario and time-slice required (obtained from
MAGICC)
Key assumption the anthropogenic climate change
patterns are independent of the history of
greenhouse gas forcing