Transcript Wang Jinxia - Overseas Development Institute

Can China Continue Feeding Itself? The Impact
of Climate Change on Agriculture, Water
Scarcity and How Farmers Adapt
Jinxia Wang
Center for Chinese Agricultural Policy (CCAP)
Chinese Academy of Sciences (CAS)
Co-authors: Robert Mendelsohn, Ariel Dinar, Jikun Huang,
Scott Rozelle and Lijuan Zhang
Food Security in China
• Policy debate:
Global food security issues
-- Especially in China
-- Many studies focus on such issues
-- Most research results in China are positive
However,
All these studies do not consider climate change
Global Climate Change
• Scientific evidence shows:
Rising greenhouse gases planet
warming
Important to understand the impacts of
global warming
• Impacts to agriculture
Largest and best documented impacts
Impacts of Climate Change on
Agriculture
• Agronomic studies (In China and other developing countries):
Climate change  reduces crop yield (-)
Assume the same crops in the same place
Without considering farmers’ adaptations
• Economic studies based on Ricardian model (Africa, South
America, Brazil, India, …):
Climate change  reduces farmer revenue
Except in cool locations and some places with irrigation (Egypt)
Considering farmers’ adaptations
• So, considering the adaptations, what will happen to China
when climate changes?
Research Questions
• What are the impacts of climate change
on agriculture (net crop revenue)?
• How do farmers adapt to climate change
(irrigation or crop choice)?
Presentation
• Methodology/Data
• Results of the impacts of climate change
on crop net revenue
• Results of the impacts of climate change
on irrigation and crop choice
• Conclusions and project justification
Economic Approach: Ricardian Model
• Regress net revenues (or land values) on
climate, soil, characteristics of village and
household
• Include climate by season in quadratic
(second order approximation) form
• Examine all farms, rainfed and irrigated
farms.
Data…
• Climate data:
- Source:
National Meteorological Information Center
- Monthly temperature and precipitation from
meteorological 733 stations
- 1951~2001
- Divide into four seasons:
Spring: 3~5; Summer: 6~8
Fall: 9~11; Winter: 12~2
- Calculate the average annual temp. and prec.
for each season using data from 1951~2001
Data…
• Socio-economic Data
-- Source:
China’s National Bureau of Statistics
Nation-wide Household Income and Expenditure Survey
-- Sample:
Counties having both meteorological stations and HH
8405 HH in 915 villages, 124 counties and 28 provinces
Data…
• Socio-economic Data
-- Net crop revenue by HH:
Gross crop revenue (or total sales for each crop) less than
All expenditures for production (seed, fertilize, irrigation,
pesticide, machinery, plastic sheeting, hired labor and custom
services, not including land rent and family labor)
Return to land and family labor
-- Household and village characteristics
Education level of household members
Family’s land area
Topographical environment of each village (plain or mountain)
Irrigation status (share of irrigated areas)
Easy to access to market (road, distance to township government)
Data
• Soil Data
-- FAO
-- Clay, sand and loam soils
-- Share of cultivated areas with each
type of soil at county level
Average Annual Marginal Impacts of Climate
Change on Net Crop Revenue in China
Changes of net revenue due to minor change of climate
(USD/ha)
All farm
Irrigated
farm
Rainfed
farm
Temperature
-10
68
-95
Precipitation
15
27
23
Minor increase of temperature will reduce the net revenue of all
farms, especially for rainfed farms; however, minor increase of
precipitation will increase the net revenue of all farms
Marginal Temperature Effect, Irrigated Farms
Warmer temperature are more beneficial in the Southeast and southwest region.
Farms in the Central region enjoys mild benefits from warming, however,
the far north will be damaged by warming
Marginal Precipitation Effect, Irrigated Farms
Almost all Irrigated farms enjoy small benefits
from increased rainfall
Marginal Temperature Effect, Rainfed Farms
Warming is likely helpful to rainfed farmers in very cold places but it will
likely harm rainfed farmers in most of China and especially the far south
Marginal Precipitation Effect, Rainfed Farms
More rain is likely to be harmful to rainfed farmers in the wet
southeast but will benefit farmers in the remaining regions
Summary: Impacts of Climate Change on
Net Crop Revenue in China
• The average impact of higher temperature is
negative and the average impact of more
precipitation is positive;
• However, effects will vary by region;
• Rainfed farmers are more vulnerable than
irrigated farmers;
• Irrigated farmers are less sensitive to
temperature and gain from increased
rainfall.
Advantage of Economic Approach
and Its Limitation
• Advantage of the Economic Approach (Ricardian
model)
-- It provides an estimate of the benefits derived from adaptation
-- After considering adaptations, farmers’ losses from warming will be
greatly reduced and even slightly gain especially for irrigated farms
-- The results of crop model can be treated as without adaptation
• Limitation on the data
-- Do not know how much water farmers used in irrigation, cannot
quantify the effect of water in the economic model
-- If climate change does reduce water supplies, there will be harmful
impacts on agriculture
Trend of Discharges at Aixinzhuang
Station：Lower Haihe River Basin
Serious Dry-up Issues in the
Downstream of the Yellow River
Increase of Groundwater Irrigation
in Northern China
Percent of groundwater irrigated area
Hebei: Falling Shallow GW Table
Hebei: Falling Deep GW Table
(1980-98)
County
Meter/year
Changes of Water Uses in China
China is facing a water crisis
• At least that is the perception of some scholars and
policy makers inside and outside of China
– Senior agricultural and water policy officials claim that
water shortages pose the largest challenge to China’s
agricultural sector in the 21st century
– Some researchers say it will seriously disrupt food
production in China
Data set 1:
2004 North China Water Resource Survey (NCWRS):
6 provinces, 50 counties, 400 villages
Inner Mongolia
Liaoning
Shanxi
Shaanxi
Hebei
Henan
Data set 2:
2001/2004 China Water Institutions and Management (CWIM) Panel
2 provinces, 9 counties, 48 villages
(village leaders, groundwater managers, surface water managers, & farm households)
Groundwater Levels are Falling, but
Varies across Northern China
Change in Average Water Level 1995-2004
（1995-2004）
• Increased :
16%
• No Change:
18%
• Decreased < 0.25 m/year ：
17%
• Decreasing 0.25 to 1.5 m/year : 40%
• Decreasing > 1.5 m/year :
8%
52%
52%
Our findings on water scarcity and
government and farmers’ response…
• There is a water scarcity… but, the scarcity is not
everywhere! There are many parts of China in which
water resources have not deteriorated over time …
• 1/2 of North China is suffering from rapidly falling
groundwater tables
• Facing with a water crisis, the government has begun to
made a number of institutional and policy responses (such
as issuing regulations, reforming irrigation management
and establishing water rights), not very effective.
• In the future, water crisis will continue to grow especially
as competition among users increase and even more so, if
there is not an effective implementation of policies
Our findings on water scarcity and
government and farmers’ response…
• Where water is becoming scarce, producers,
community leaders are responding
Digging tubewells by individuals
Developing groundwater market
Reducing water use and changing cropping
patterns when water price increases
Adopting water saving technologies
However, faced with water scarcity, some responses are
helping, some are hurting
Hence, Government cannot ignore response of farmers,
in fact they need to use this responsiveness to reduce
adverse effects and encourage conservation
When Climate Changes, How
Farmers Make Response?
• How will changes of temperature
and precipitation influence irrigation
choice?
• How will changes of temperature
and precipitation influence crop
choice?
Annual Marginal Effect of Climate Change
on Irrigation Choice in China
Sign of Marginal Effect
Temperature
_
Precipitation
_
Increasing temperature and precipitation will promote
farmers to switch from irrigated agri. to rainfed agri.,
Chinese farmers are more likely to irrigate when facing
lower temperatures and less precipitation
Annual Marginal Effect of Climate
Change on Crop Choice in China
Wheat
Maize
Rice
Cotton
Oil
Potato
Soybean
Sugar
Vegetable
Temperature
+
+
+
+
-
Precipitation
+
+
+
+
+
+
Summary: Adaptation Results
• As temperatures warm, move away from
cool loving crops towards heat tolerant
crops
• As precipitation falls, move away from
wet loving crops towards drought
tolerant crops
Conclusions …
• Different from pessimistic results of the crop studies,
economic results show that the impact of climate
change on agriculture are smaller;
• The major reason is that economic method implicitly
captures the adaptations, such as crop switching,
changes in irrigation and other changes that farmers
might undertake;
• The mildly harmful marginal effect of higher
temperature is mainly due to two reasons:
-- Large irrigated areas
-- Rainfed land in temperate or cool regions
• So, irrigation is critical to China’s agriculture system;
• If warming forces many irrigated farms to become
rainfed farm, the positive results will be reversed
Conclusions
• The effect of climate change varies by region
• It is very important to explore regional
adaptation measures (such as water policies)
that fit the conditions in each region, rather
than uniform national policies
• The ability of Chinese farmers to adapt to
climate change is very important, government
should support adaptation at large
So, it is very important to implement adaptation
project on climate change!