Sample Presentation

1
The 90-10 rule Rob Wilby, Loughborough
University r.l.wilby_at_lboro.ac.uk
Photo Sergio Mora
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Testing conventional scenario approaches to
destruction in arid and semi-arid zones
Photo Bull (1930)
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MENA a region of water scarcity NOW
Source United Nations Statistics Division (2005)
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Top down approaches may be defensible where the
map is coloured....
Blank areas show where there is lt66 consensus
about the sign of change amongst the IPCC climate
model ensemble
Source IPCC AR4 (2007)
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...but adaptation decisions must still be robust
to large climate and impacts model uncertainty
Projected changes in spring and annual
precipitation totals at sites across Morocco for
the 2080s for two downscaling methods (UCT, SDSM)
and three climate models (CSIRO, ECHAM4, HadCM3)
under A2 emissions Source Wilby DMN (2007)
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Bottom up approaches make more sense where the
map is blank
Blank areas show where there is lt66 consensus
about the sign of change amongst the IPCC climate
model ensemble
Source IPCC AR4 (2007)
7
Example low regret adaptation options for Yemen

• Science and climate risk information
• Centralising data collection and dissemination
• Supporting meteorological data rescue and
  digitization
• Monitoring baseline environmental change
  (indicators)
• Improving surface and groundwater resource models
• Improving scientific understanding of regional
  climate variability
• Developing real-time, seasonal and decadal
  forecasting capability

• Water management
• Improving water governance and methods of
  allocation
• Undertaking source protection from pollution and
  salinization
• Increasing agricultural (and urban) drainage
  water re-use
• Undertaking asset management and maintenance
  (leakage control)
• Improving water efficiency (domestic,
  agriculture, industry)
• Developing faster growing and/or more drought
  resistant crop cultivars
• Employing traditional water harvesting and
  storage techniques

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Yemen NAPA How many of these proposal really
need climate model projections?
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The 90-10 rule

• Low regret adaptation options are needed that
  assist poverty and hazard reduction NOW...but
  also address future risks...
• Such measures can often be identified without the
  aid of climate change scenarios (90)
• The cascade of uncertainty means that there are
  very few examples of scenario-led adaptation
  anywhere (10)
• Climate scenarios best used for evaluating
  performance of options or bounding sensitivity
  tests rather than optimisation