The Global Gridded Crop Model
Intercomparison – Approaches, insights and caveats of modeling
climate change impacts on agriculture at the
global scale.
Christoph Müller, Joshua Elliott
& the Ag-GRID team
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Climate, Agriculture, Markets
Nelson et al. 2013
Consumer
preferences
Population
GDP
Market
flexibility
Planting
dates
Varieties
Fertilizers
Irrigation
Crop mix
GHG
GCM
bias-
correction
interpolation
Modeling choices
www.ISI-MIP.org
www.isimip.org
www.AgMIP.org
Rosenzweig et al. 2013a
ISI-AgMIP fasttrack
• 7 GGCMs – EPIC, GEPIC, IMAGE-AEZ, LPJ-GUESS, LPJmL,
pDSSAT, PEGASUS
• ~500 scenarios – 5GCM * 4 RCP * 2 irrig * 2 CO2 *7GGCM
• 3-16 crops
• Rainfed & fully irrigated
• With and without CO2 fertilization
• 67420 locations (0.5°*0.5° grid)
Rosenzweig et al. 2013b
IPCC AR4 update for AR5
Rosenzweig et al. 2013b
IPCC AR4 update for AR5
Rosenzweig et al. 2013b
CO2 fertilization
Deryng et al. under review;
Rosenzweig et al. 2013b
Water consumption
Deryng et al. under review
Elliott et al. 2013
Indirect impacts
ISI-MIP: Constraints and potentials of future irrigation
water availability on agricultural production under
climate change (Elliot et al., under review)
Elliott et al. 2013
Limits to adaptation
Waha et al. 2013
Adapted sowing dates
Adapted cropping sequence
kcal/ha
Adaptation options
Piontek et al. 2013
Adaptation challenges
Piontek et al. 2013
Adaptation challenges
Nelson et al. 2013
Economic response
Spatial patterns
Müller & Robertson 2014
IMPACT DSSAT EPIC LPJmL pDSSAT PEGASUS
Maize Maize Maize Maize Maize Maize
Millet Maize ** Sorghum Millet *** ****
Rice Rice Rice Rice Rice ****
Sorghum Maize ** Sorghum Millet *** ****
Wheat Wheat Wheat Wheat Wheat Wheat
… … … … … …
Sub-tropical fruit * * * *** ****
Sugar beet * * Sugar beet *** ****
Sugar cane Maize Sugar cane Sugar cane *** ****
Sweet potatoes * * * *** ****
Temperate fruit * * * *** ****
Vegetables * * * *** ****
Other crops * * * *** ****
Commodity mapping
Nelson et al. 2013
Nelson et al. 2014
Commodity mapping effects
Schmitz et al. 2012
Externalities
Ch
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Schmitz et al. 2012
Externalities
Ag-GRID
• Organizing hub for gridded crop modeling and data within AgMIP.
• Includes >18 modeling groups so far and >10 data partners
• Helps coordinate global and regional multi-model assessments.
• Synthesis platform for AgMIP data, expertise, IT, etc.
• GGCMI: flagship project of Ag-GRID
• 3 distinct model types: 1) Gridded process models, 2) Dynamic global vegetation and land-surface models, 3) Empirical/process model hybrids
22
• Nine reanalysis-based historical weather
products spanning 1948-2012
• Harmonized on fertilizer, sowing, maturity, etc.
• Additional focus on large-scale
extreme drought/heat events in
the historical record.
Phase I: Historical evaluation
• Phase II: CTWN
– Multi-dimensional sensitivity study of model response
to carbon, temperature, water, and nitrogen.
• Phase III: Coordinated assessment
– Vulnerabilities, impacts, and adaptations
– New set of future climate forcings from CMIP5 and
CORDEX
– Detailed set of adaptation scenarios developed in the
AgMIP Representative Agricultural Pathways (RAPs)
framework
Future phases
Thanks