This document summarizes a project that used regional climate models and crop models to assess the potential impacts of climate change on agriculture in the Southwestern US and Korean Peninsula. The project utilized multiple regional climate models and crop models to simulate yields under historical and future climate scenarios. The results showed that maize yields in both regions could decrease significantly by 2050 under climate change without adaptation. However, shifting to earlier optimal planting dates by around 20 days helped maintain similar yield levels to historical periods in the Korean Peninsula by avoiding frost and extreme heat stresses.

1. Using a Multi-Model Regional Simulation of
Climate Change Impacts on Agriculture in
the Southwestern United States and Its
Application to a Research Framework in
the Korean Peninsula
Project Director: Menas Kafatos, Chapman University
(NIFA Award: 2011- 67004-30224)
Agroclimatology PD

2. Overview
Objective
• To assess the potential impacts of climate variability and change on ecosystems and agriculture
in semi-arid regions, specifically the Southwestern US (SW US).
Approach
• Utilize accurate regional
modeling, and capture
climate impacts at
regional ecosystem
scales
• Inter-compare multi-crop
model simulations driven
by regional climate
models and create an
ensemble to reduce
uncertainties in
forecasting crop yields.
Impact
• A better understanding of the relationship between climate variability and ecosystems and
agriculture in the SW US.
• Simulate future yield projections for use by growers and decision makers
A schematic illustration of the data flow from
climate projection to crop productivity
assessment in a typical nested modeling using
a agricultural model.
Agroclimatology PD

3. Future Projection of Agroecosystem
Maze Yp changes between historical (1981-2000) and
future projection (2031-2050).
[Kim et al., 2016]
[Medvigy et al., 2016]
Impact of warming
Impact of Downscaling
deciduous tree leaf
emergence in California
under current and future
climate
Agroclimatology PD
Future projection based on RCP85
shows decrease of maize yields over
the warmer climate region in the SW
US. Changing sowing date in future
alleviates significant Yp decrease under
climate change.

4. Impacts of Climate Variability
Impact of NAO (North Atlantic Oscillation) on
the early warm season temperature in SWUS
Temperature, Sowing dates, and Yield Potential of Maize in
the Southwestern US
RED (WARM): Early planting/harvesting favors higher yields due to
the extremely hot summer.
BLUE (COOL): Early planting and late harvesting (lengthening GS)
favor higher yields.
YELLOW (INT): Late planting/harvesting favors higher yields, which
can take advantage of “mild” (25~35°C) summer climate.
[Myoung et al., 2015] [Myoung et al., 2016]
The NAO-Ts linkage in SWUS has been strengthened in the last 30-year period (1980-2009)
compared to the earlier 30-year period (1950-1979).
NAO-Ts relationships are primarily due to positioning of upper-tropospheric anticyclone in
the western US that is associated with development of positive NAO phases in the Atlantic.
Agroclimatology PD

5. Results: 21-year Ave. of the OPT run
WARM: Warm low-elevation regions
COOL: Cool high-elevation regions
INT: Intermediate regions
(kg/ha)(month)
(day) OPT-FIXED YLD diff (%)
COOL
INT
GS: Growing season (from SD to
HD)
Region SD
(Sowing
date)
HD
(Harvest
date)
LGS
(Lengt
h of
GS)
YLD
(Yield
Poten.
)
WARM Very early
(Mar)
Early
(Jun & Jul)
Short Low
COOL Early (Apr) Late
(Sep & Oct)
Long High
INT Late
(May &
Jun)
Late (Sep) Short High
Suitable management decisions can
substantially enhance yield potential over many
places.
Summary of the variables
Agroclimatology PD

6. Assessment of Future Maize Yield
Potential Changes in the Korean
Peninsula Using Multiple Crop Models
2Seung Hee Kim, 3Chul-Hee Lim, 4Jinwon Kim, 3Woo-Kyun Lee,
1Menas C. Kafatos
1Fletcher Jones Endowed Professor of Computational Physics,
Chapman University
Outstanding Visiting Professor, Korea University, Seoul, Korea
Affiliated Researcher, National Observatory of Athens, Greece
2Chapman University, 3Korea University, 4UCLA
Agroclimatology PD

7. The Korean Peninsula has unique agricultural environment due to the differences of political and
socio-economical system. NK has been suffering lack of food supplies caused by natural disasters,
land degradation and political failure. The neighboring developed country SK has better agricultural
system but very low food self-sufficiency rate (around 1% of maize). Maize is an important crop in
both countries since it is staple food for NK and SK is No. 2 maize importing country in the world
after Japan. Therefore evaluating maize yield potential (Yp) in the two distinct regions is essential to
assess food security under climate change and variability.
Motivation
Agroclimatology PD

8. Orange Boxes show improved/modified components
Map RCM data
onto geographic
areas of interests
Quality Control of
met forcing data
Evaluation/bias
correction
Bias-corrected RCM data (PR, T, etc.)
Agricultural model
(APSIM)
Crop
productivity
assessmentManagement
decisions,
Korean Policy
makers
GCMs +
emissions
scenarios
Global climate
scenarios
RCMs
over East Asia
Downscaled
climate scenarios
Obs. PR, T, etc..
Observations
GIS information
over Korea
Agroecosystem
model
(EPIC and GEPIC)
Agricultural
water demand
assessment
Agroclimatology PD

9. Crop Model Validation
[Mgha-1][Mgha-1]
Blue shaded
region is simulated
Yp at each region
and black solid line
shows median of
the Yp. Box plot
shows observed
yields.
Agroclimatology PD

10. Time series of Maize Yp with adaptation strategies[%][%]
[%]
Fixed Planting Date Optimal Planting Date
3/21
3/31
4/10
4/20
4/30
5/10
5/20
5/30
6/9
2031 2033 2035 2037 2039 2041 2043 2045 2047 2049
Adaptation (shifting planting date)
Optimal planting date
shifted 20 days earlier
Agroclimatology PD RCP8.5 shows 10 to 20% decrease of
maize yields potential

11. Adaptation (shifting planting date)
3/21
3/31
4/10
4/20
4/30
5/10
5/20
5/30
6/9
2031 2033 2035 2037 2039 2041 2043 2045 2047 2049
The optimal planting date is shifted about 20 days earlierAgroclimatology PD

12. Summary
 The yield sensitivity varies geographically according to
regional mean climate states.
 Both crop models are reasonably well represent the actual
yield in the Korean Peninsula.
 Future projection based on RCP8.5 scenario shows
significant decrease of maize yields potential.
 However, with proper adaptation strategies, the maize
yields potential stays in similar level of historical period.
 Optimal planting date is shifted about 20 days earlier in
the mid-century because it helps to avoid damages from
frost in spring and extreme heat in summer.
Agroclimatology PD