Chinese Academy of Agricultural Sciences.
Assessment of climate change impacts
on agriculture and a case study on crop
impacts in China
Sanai Li
APEC Climate Center, Busan, 612-020,
Republic of Korea
Erda LIN
Chinese Academy of Agriculture Science, Beijing, China
Outline
 Why is climate change such an
important issue for agriculture?
 Introduce the crop models
- the response of crop to temperature
- the response of crop CO2
- the response of crop water
 Assess the impacts of climate change on
agriculture –case study in China
 Adaptation strategies in agriculture
Importance of Agriculture
 70% of the global land use is for
agriculture, rangeland and forestry
– 12% for arable and permanent crops
– 31% for forest and woodlands
– 27% for permanent pasture.
 Agriculture remains the major source of
livelihoods of majority of world’s rural
poor.
-agriculture accounts for 70 percent of
full-time employment in Africa, 33
percent of total GDP, and 40 percent of
total export earnings.
-Asia-Pacific region 60 percent of the
population (2.2 billion) is relying on
agriculture as a source of livelihood
 Agriculture is one of the most sensitive
sectors to impacts of climate change
Climate Change & Agricultural
productivity
 Climates factors directly affect agricultural productivity:
-average increase in temperature
-change in rainfall amount and patterns
-rising atmospheric [CO2]
-increase in climatic variability and extreme events
-pollution levels such as ozone
What is the current impact of climate change on agric
ulture production ?
changes in maize and wheat
production1980–2008
Currently global maize and wheat
production declined by 3.8 and 5.5%,
respectively relative to without climate
trends ( increase in temperature and CO2,
changes in rainfall)
soybeans and rice, winners and losers
largely balanced out
Source: Lobell et al., 2011
5
Current observed impacts of climate change on agriculture in
China
In northeast China winter wheat planted has been
extended to north by 2-3 latitude (about 250km)
Frequent freezing damages to wheat production in China- for
example In 2004 and 2005, the wheat freezing damage area
reach 3.33 million hectares in 6 provinces including Henan,
Shangdong and Hebei provinces
Plant diseases and pests are currently causing a 20%-25%
average annual loss to China’s agriculture output value
Climatic regionalization of winter wheat in Liaoning province (Ji et al., 2003)
6
Future challenges

We need sustained growth in the agricultural production
-to feed the world
-to enhance rural livelihoods
-to stimulate economic growth

The demand for food will double
within the next 25-50 years,

Food security, remains a
challenge, particular in
developing countries
7
Climate and Agriculture
Studies of the effect of weather
and climate on agriculture are
often limited by the availability of
climatological data and
experimental results.
The interactions between the
plant and its environment cannot
be reflected by the simple cropclimate regression
 Crop models provide useful
tools for analysing crop and its
relationship with the climate.
8
Crop growth and development
Growth-increase in size
 normal measure in dry weight
 also Leaf Area Index
Leaf area index (LAI) is the total one-sided green leaf area per
unit ground surface area
LAI= total green leaf area / ground surface area
9
Development-progress to maturity
Through different stages-eg: emergency, flowering, graining
filling, harvest
 The time-span of each development phase depends on
genotype, temperature, day-length and sowing date

Flowering(61-69) graining filling(71-87)
Emergency(9days)
harvest
(97-110)
10
Outline
 Why is climate change such an
important issue for agriculture?
 Introduce the crop models
- the response of crop to temperature
- the response of crop CO2
-the response of crop water
 Assess the impacts of climate change on
agriculture –case study in China
 Adaptation strategies in agriculture
Crop simulation models
 Site based crop models (e.g DSSAT) :
Seek to simulate the complex
dynamics of crop growth and
development, and its response to
environmental variables
 Large area crop modes (e.g. GLAM):
Applied some simple assumptions and
empirical relationships to predict the
complex crop growth and
development
Site based Crop models
High input data requirement
Complexity of incorporating the spatial variability of input
Climate model output is coarse compared with input to crop model
This method is difficult
to apply at
a regional level
(Yang.P).
13
General Large Area Model for annual
crops (GLAM; Challinor et al, 2004)
 Aims to combine:

the benefits of more empirical approaches (low input data requirements, validity
over large spatial scales) with

the benefits of capturing intra-seasonal variability, and so cope with changing
climates)
 Field management -Yield Gap Parameter
 Groundnut, wheat, maize, soybean
general
circulation
model
crop
model
Irrigation Models
Irrigation strategies – farm level
 CROPWAT (FAO)

Crop water requirements, irrigation requirements
based on climate, soil type, rainfall, reference ET,
cropping patterns
 AIMM (Alberta Irrigation
Management Model)


Irrigation and scheduling decisions for 52 different
crops
Weather, soil moisture, ET, irrigation application
methods
 WaSIM (UK)

Water balance simulation model
15
Site based crop models
Wageningen models (CSIRO, Australi
a)
 Simulate potential production under measured
climatic conditions
 Limitations in simulating cropping systems and
dynamics in soil water, nutrients and soil
organic matter
DSSAT
 Include CROPGRO and CERES models, 17 crops
 Simulate crop growth, development and yield
as well as soil water and nitrogen balances.
 Yield limiting factors such as pests, diseases
and field management, are not included
16
Site based crop models
 APSIM
 Produce accurate yield simulation in
response to management and predict the
long-term impact of farming practice on
the soil resource
 CropSyst (U. Washington)
 Simulate the impact of climate, soils and
management on cropping systems
productivity and the environment.
 Representation of crop rotations
17
Risk modelling
-NADSS (National Agricultural DSS) USDA and
UNL
 Web-based tools
 Identify patterns of drought at
regional and national level in the
USA
 Drought indices, crop production risk
analysis
 Map and tabular format
18
Risk modelling AgRisk (OSU)
 PC software
 Predict farm’s gross revenue at
harvest time (corn, soybean, wheat)
under different pre-harvest risk
management strategies (crop
insurance, current and future market
information)
19
GPFARM (Great Plains Framework for Agr
Resource Management) - USDA
 PC software, farm level use
 Three components:



Crop growth, animal growth, water balance, water
erosion, environmental impacts
Economic analysis tool – estimate costs of
rangeland crop production, various cost-benefit
analyses
Agricultural information system – web-based links to
information on crops, pests, agricultural chemicals
20
Whopper Cropper (Australia)
 PC software
 Uses both seasonal climate
forecasting and crop system
modelling to estimate production
risks in upcoming season
 7 crops in Australia
 Uses “what if” scenarios to help
farmers decide which crops to plant,
when to plant, which varieties to
plant and how much to invest on
various inputs (nitrogen)
21
Outline
 Why is climate change such an
important issue for agriculture?
 Introduce the crop models
- the response of crop to temperature
- the response of crop CO2
-the response of crop water
 Assess the impacts of climate change on
agriculture –case study in China
 Adaptation strategies in agriculture
Temperature and crop growth
 All plants have maximum, optimum and
minimum temperature limits. The limits
are cardinal temperature points
 Optimum temperature is required for
maximum dry matter accumulation
Temperature and crop development
The development rate of crop is mainly dominated by temperature
Cardinal temperature values
for selected annual crops under
conditions in which temperature is the only
limiting variable
25
Linear trend in temperature from 1961-2009
during rice growing season in Asia
In Asia maximum temperatures has
increased by roughly 0.5-1o since
1961 in rice growing region
minimum temperatures has
increased by roughly 0.5-1.5o
26
The impact of current warming trend on rice yield in
Asian countries for 1961-2009
Correlations between temperature and rice yield from 1961-2009 in
Asia countries
27
What is the current impact of warming trend on rice yield in
Asian counties?
Viet Nam
Thailand
Sri Lanka
Philippines
Pakistan
Nepal
Malaysia
Laos
Japan
India
China
Cambodia
Bhutan
-15
-10
-5
0
5
10
yield reduction % for 1961-2009
In Asia rice yield has declined by 2.3-10.8% due to the warming
trend in maximum temperature from 1961 to 2009
In Japan and Srilanka the warming trend has a positive impact on
rice yield
28
Impact of extreme temperature on rice yield
Relation between average daily maximum temperature and spikelet
fertility during the flowering period under different CO2
concentrations(Horie 1993)
.
29
Impact of cooling on rice yield
Relation between cooling degree-days and percentage
spikelet sterility between the booting and flowering stages
(Horie 1988)
30
Global mean temperature is increasing
Effects Shift in vegetational zones
Heat stresses on plants
Soil moisture
Pests and diseases
31
Outline
 Why is climate change such an
important issue for agriculture?
 Introduce the crop models
- the response of crop to temperature
- the response of crop CO2
-the response of crop water
 Assess the impacts of climate change on
agriculture –case study in China
 Adaptation strategies in agriculture
Modelling growth: photosynthesis
Photosynthesis: A chemical process by which a plant turns light energy from the sun
into chemical energy in the form of sugar.
33
Crop radiation interception
Regard a crop as a machine that intercepts solar
radiation and convert its energy stored in plant
material
Incident radiation is intercepted by the crop or
transmitted to the soil
Intercepted radiation is then reflected or absorbed
Fractions: incident=1
Intercepted=incident -transmitted
Intercepted=1- transmitted
Absorbed=intercepted-reflected
Absorbed=1- transmitted -reflected
34
Modelling growth: Radiation Use Efficiency
The potential or maximum photosynthesis of a crop canopy can be estimated from a
set of parameters describing the photosynthesis-light curve of single leaves.
35
Modelling growth: biomass
 Biomass=RUE*
intercepted solar
radiation
 RUE normally
increase with
more N
 RUE decreased
by significant
stress eg. water
van Ittersum,2003
36
Increased CO2 concentration
increase the CO2 gradient between the
atmosphere and the inside of leaves,
Increase rate of photosynthesis
increase growth rate and
productivity of plants
decrease transpiration
increase crop water use efficiency and
yield
Photosynthetic response to rising CO2
At a certain level of CO2
photosynthesis will saturate"
38
Free Air CO2 Enrichment (FACE)
FACE is the technology by which the environment around growing plants may
be modified to realistically simulate future concentrations of atmospheric
carbon dioxide (CO2).
Long et. all 2006
The response of winter wheat to rising CO2
-FACE experimental results in China at 550 ppm CO2
Han Xue et al 2012
40
Outline
 Why is climate change such an
important issue for agriculture?
 Introduce the crop models
- the response of crop to temperature
- the response of crop to CO2
-the response of crop to water
 Assess the impacts of climate change on
agriculture –case study in China
 Adaptation strategies in agriculture
Importance of Rainfall
•
•
Rainfall is especially important for rainfed or dry
land agriculture
Arid and semi-arid areas account for about 40% the
land surface of the world, especially some African
countries, where rain-fed agriculture is already
limited by water availability (Gamo, 1999).
Low Rainfall – Poor Crop
Sufficient Rainfall – Good Crop
Water stress on crop
 Stress during early growth
can stimulate root growth,
extreme drought can delay
planting and damage seed
germination
 Stress at flowering may be
more sensitive (maize)
 During the grain filling
period, water deficit can
reduce grain weight by
accelerated senescence rate
and shortened growth
duration
43
The response of rice yield to seasonal total rainfall
from 1961-2009 in Asian countries
In india, Laos, Nepal,Thailand and Asia, seaonsal total rainfall has a positive
impact on rice yield, viriability of rice yield depends on the amount of rainfall
In Japan, rice yield showed a negative response to seasonal total rainfall
44
Impact of extremes: rainfall distribution
1975
Total rainfall: 394mm
Model: 1059 kg/ha
Obs: 1360 kg/ha
1981
Total rainfall 389mm
Model: 844 kg/ha
Obs: 901 kg/ha
45
Drought mitigation and adaptation
 Avoid stress at sensitive
stages-floral initiation and
pollination
 Adjusting planting structure
or sowing date
 Seed Engineering-choice of
cultivar tolerance to
drought
 Rainfall collection based
water saving
 Membrane coverage
 Protected cultivation（Less
tillage and no tillage ）
Outline
 Why is climate change such an import
ant issue for agriculture
 Introduce the crop models
- the response of crop to temperature
-photosynthesis,CO2 and crop
-the response of crop to water
 Impact of climate change on
Agriculture –case study in China
 Adaptation strategies in agriculture
 im
Impacts of Climate Change on
Chinese Agriculture – Phase II
Integrated impact assessment including
socio-economic scenarios
Climate Change;
CO2 fertilization effects;
Water Availability;
Agricultural land conversion;
All drivers together
48
CLIMATE SCENARIOS from PRECIS
CERES crop model
VIC hydrological
model
IMPACTS ON TOTAL PRODUCTION
GDP, Pop., Water demand,
Land use
ADAPTATION POLICIES
IMPACTS ON CROP YIELDS, WATER
AVAILABILITY, AND ARABLE LAND
SOCIO-ECONOMIC
SCENARIOS
Improvements in
Agric. Tech.
Land use change
policies
Water allocation
policies
Comparison of PRECIS results and GCM output for China
2020s
Precipitation change (%)
20
2050s
2080s
15
PRECIS 2020s
PRECIS 2050s
10
PRECIS 2080s
5
0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
-5
-10
Temperature change (degree C)
– Annual change in temperature and rainfall
in China: 2020s, 2050s, and 2080s
– 17 GCMs from IPCC and PRECIS (A2
emissions)
Change in total cereal production with
different combinations of drivers
Climate Change
With CO2
Only Climate Change
Climate Change
All drivers
With CO2 and water
Climate Change
Climate Change
With Water
Water & Land
Cereal per capita (kg)
Changes in cereal production per capita
in China under combinations of drivers
320
CC only A2
300
CC/CO2 A2
280
CC/CO2/WA A2
All drivers A2
260
CC only B2
240
CC/CO2 B2
220
CC/CO2/WA B2
200
All drivers B2
180
2000
2020s
2050s
Future impacts of climate change on
agriculture in China
The reduction in crop yield by 3.2-3.6℃ temperature increase
during 2080s can be offset by elevated CO2 at 560-720 ppm and
other adaptation, but very high costs may need.
An increase in investments of 8 ~ 34.8 billion US dollars per year (in 1990 price) is
necessary, otherwise the agriculture will lose 32.3 ~ 80 billion US dollars per year
(Lin, & Zhang, 2005)
53
How we are responding to climate change
Action to address climate change
 Mitigation: Reducing greenhouse
gas emissions
 Adaptation: A process of adjusting
to changes in variables
54
An adaptation framework for China
to support national and international adaptation projects
New knowledge/
research
1 Assess climate
risks
6 Monitoring and
evaluation
2 Integrate development
and adaptation goals
Integrate adaptation
into planning and
policy framework
5 Implementation
3 Identify adaptation
options
4 Prioritise options
Climate change by 2030 will further aggregate the drought stress
in Northeast China
Percentage of crop production loss
due to drought stress in Northeast
China1 （2030）
+35%
probability
Northeast China
*
30%
10%
crop yield loss
due to drought
million ton
Economic loss
Billion RMB
Current
climate
Future
climate
4.4
6.0
6.5
8.7
Rainfall in spring (mm)
Factors causing yield loss

Decrease in the amount of rainfall

Increase in extreme drought stress

Less investment in agriculture and infrastructures avoiding drought stress
1 历史气候：假设2030年具有相同的气候条件; 气候变化：高二氧化碳浓度的情景（2050年 559 ppm）
来源：PRECIS 模型；团队分析
56
the economic costs and benefits of drought adaptation
-Case study in Northeast China by 2030
*
(cost/benefit<1)
3.7
*
evitable
loss
~56%
*
*
(cost/benefit>1)
inevitable
loss
~44%
inevitable loss
*
*
*
*
*
*
*
*
*
*
18
10
Pipe delivery water
Seed
Reservoir and pond
Engineering
evitable loss
Billion RMB
Long term
economic
benefit
Spray
Canal seepage
Drip
for irrigation
Irrigation
Irrigatio
*
Rainfall collection based water saving
n
Protected
cultivation ）
Membrane coverage
-3.1
*
*
In northeast China, yield loss due to drought stress can be avoid by 56%
by the above adaptive measures
资料来源：麦肯锡分析
Adaptation Demonstration in China
Demo.
areas
Heilong
jiang
Heihe basin,
GS
Tailanhe
basin, XJ
Naqu
Tibet
CC Risk
Cooling dec.
getting dryer
Water
consuming
increase for
oasis
Adap. Target
Go benef,
avoid
disaster
Water saving &
cultivat
Saving water
and ecolog.
protect
Protect
grassland
ecology
Build design
based on sea
level
Poten. Adapt.
Structure
adjusting
Low consuming
technology
Integrated water
management
pasture
animals b. on
water
Design stand
with s.le. rise
Adp. Asse.
31
30
30
28
26
Demon.
700 hm2 x 4
20 hm2 land
10 reserv. 60
hm2 land
sprinkled
Irrigat.12hm2
Project design
in costal ar
More water
Grassland
coming now and dryer, lake level
will decrease
rise
Bohai
Coast
Sea level rise,
storm tide
How farming can adapt to the changed climate
farmers can:
 change their crop rotation to make the best
use of available water,
 adjust sowing dates according to
temperature and rainfall patterns,
 use crop varieties better suited to new
weather conditions (e.g. more resilient to
heat and drought)
Public policy must support farmers
59
Policy recommendations
 Improve the capacity of farmers and rural
regions to adapt to climate change



Develop systems for monitoring regional climate
change and provide early warning of disasters
adapting options to the farming community
providing advisory services and training.
Policy recommendations
 Support the development of low-carbon,
high-quality Agriculture
 Comprehensive, long-term strategy based on local
circumstances
 Long-term subsidies to encourage investment in
new technology
 Market incentives: National Voluntary Carbon
trading Mechanism to pay impoverished farmers for
reducing pollutants and GHG emissions
Future work: Integrated impacts assessment
 around the world the socioeconomic environment,
world trade, population,
technology and the natural
resources are likely to
undergo significant changes
over the next few decades
(Nakicenovic and Swart,
2000)
 Integrated impacts studies
including socio-economic
scenarios, population and
improvements in technology
are an important aspect for
study.
62
Future work: assessing costs and benefits of
adaptation
 Assessing availability of water supplies for
irrigation and the costs of adaptation
 the economic and social costs and benefits
of adaptation, and the adaptive capacity
Terrace
Membrane coverage
63
Future work: Sampling uncertainty in impact assessments
Possible sources of uncertainty in predicting
climate change and its impacts:
Scenarios from population,
energy,economics models,Coupled climate
Models, Impacts models
sample the uncertainty in projections of
impact by:
using > 1 emissions scenario
using > 1 climate model
using >1 crop model
by systematically varying parameters in climate or crop
models
impact is then given by the ensemble mean, and the
variability within the ensemble
64
Key Messages
 Climate change and the extreme events have had an impact
on agriculture. Yield potential is likely to decline due to
even small rises in global temperature
 regions that will be more vulnerable
--tropical and subtropical , heat and drought stress in summer
is likely to increase
--in some northern the risk of drought stress would likely
increase
 Prioritisation of adaptation include
--adjusting planting systems
--increasing water use efficiency
--encouraging agroecological sustainable development
 An increase in investments of agriculture is necessary to secure
the food supply
--infrastructures against floods and droughts
--increasing the support to climate related scientific and
technological work
 Science and technology must spearhead agricultural
production in the next 30 years at a pace faster than the
Green Revolution’s during the past three decades.” – FAO
Director General 2007
65
Thank you for your
attention!