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Agriculture
Can We Feed The World?
Grant R. Cramer
Plant Biology 330
Fall 2001
Humanity has grown in numbers over
time
Millions of people
7,000
6,000
5,000
4,000
3,000
2,000
1,000
0
0
500
1000
1500
Year
2000
2500
Population (billions)
Global Population Continues to Rise
10
9
8
7
6
5
4
3
2
1
0
1950
1960
1970
1980
Africa
Europe
North America
1990
2000
2010
2020
2030
2040
Asia and Oceania
Latin America and Caribbean
2050
Different Assumptions,
Different Projections
World Population (billions)
12
10
8
6
4
2
0
1950
1960
1970
Low
1980
1990
2000
Medium
2010
High
2020
2030
2040
Fertility Declines, Real and Projected
Children per Woman
(2.1 = no population growth)
7
6
5
Developing
Developed
Africa
Asia
South and Central America
4
3
2
1
1950 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050
Decrease in population growth rate
• NOT associated with wealth, gross national
product or economic development
• IS associated with increased education,
especially the education of mothers
(percent)
More Children Are Attending School
100
90
80
70
60
50
40
30
20
10
0
1980
World
1990
Africa
1994
Latin
America
and the
Carribean
Asia
Europe
Oceania
(percentage of people older than 15 who
are literate)
More Adults Can Read
100
90
80
70
60
50
40
30
20
10
0
1980
World
Africa
1985
1990
Latin America
and
Caribbean
1995
Asia
Europe
Oceania
Yields Are Up, But Growth is Slowing
Yield (metric tons/hectare)
5
4
3
2
1
0
1960
1965
1970
Wheat Yield
1975
1980
Rice Yield
1985
1990
1995
2000
Maize Yield
Yields Are Up, But Growth is Slowing
12
10
% Increase in Yield
8
6
4
2
0
-2
1960
1965
1970
Wheat
1975
1980
1985
Paddy Rice
1990
1995
Maize
2000
Trends in Per Capita Food Production
Index Numbers 1961=100
180
U.S.S.R. (former)
Asia
World
160
Africa
Europe
Latin America
140
120
100
80
1961
1966
1971
1976
1981
1986
1991
1996
Intensive Agricultural has Benefited
Mankind
• 24% more food per person today than in 1961
despite an increase of 89% more people
• 40% lower food prices than in 1961 (in real
terms)
Demand for Food Growing Faster than
Population
• Increase in affluence leads to greater meat
consumption
• Meat production growing 50% faster than crop
production
• Meat production much more energy intensive
• 7 kg of grain per kg of pork; 5 kg of grain per 1
kg of beef; 2 to 3 kg of grain per kg of eggs,
cheese or poultry
Despite Gains, Millions Go Hungry
Final Analysis
• Economic and agricultural development do not
necessarily abolish hunger
• Equitable distribution is also important and is
governed by social, economic and political
influences
Weather and Climate Profoundly Affect
Crop Production
• Affects sunlight, moisture, temperature and
natural disasters
• By far, the lack of water is the most significant
constraint to agricultural production in all
agricultural zones: tropical, sub-tropical and
temperate
• Temperature also constrains crop production in
the temperate zones
Humans Can Affect the Climate and
Influence Agricultural Production
• Desertification in the Sahel
• Greenhouse Effect
Global warming enhanced by emissions
of man-made gases
5/24/2017
Source: “Climate Change, State of Knowledge,” OSTP, 1997
Greenhouse gas warming
Other
Halocarbons
5%
CFC-12
6%
Carbon Dioxide
64%
Nitrous Oxide
6%
Methane
19%
Much is known with certainty about
global warming:
• Existence of natural greenhouse effect is established
beyond doubt
• Concentrations of greenhouse gases (GHGs) are
increasing
• The temperature of the earth is increasing. 1998 the
hottest in at least 1000 years.
• Sea levels are rising (4 to 10 inches over past 100 years)
• Some GHGs will remain in the atmosphere for centuries
5/24/2017
CO2 is building up in the atmosphere
5/24/2017
Source: “Climate Change, State of Knowledge,” OSTP, 1997
Atmospheric methane (CH4)
concentrations
Data Source: D.M. Etheridge et al. Concentrations of CH4 from the Law Dome (East Side, "DE08" Site) Ice Core(a), Commonwealth
Scientific and Industrial Research Organisation, Aspendale, Victoria, Australia. September 1994. Available:
http://cdiac.esd.ornl.gov/ftp/trends/methane/lawdome.259. M.A.K. Khalil, R.A. Rasmussen, and F. Moraes. "Atmospheric methane at Cape
Meares: Analysis of a high resolution data base and its environmental implications." Journal of Geophysical Research 98:14,753-14,770.
1993. Available: http://cdiac.esd.ornl.gov/ftp/db1007/cmeares.mon
Earth’s temperature continues to rise
rapidly
Source: “Climate Change, State of Knowledge,” OSTP, 1997
Earth is projected to grow warmer
Source: Univ. of East Anglia, IPCC
The polar ice cap is melting
Uncertainties still persist
•
•
•
•
Timing and regional impacts
The effects of increased cloudiness
Uncertain health and ecological impacts
Possible surprises from unanticipated effects
5/24/2017
More impacts of global warming
can be expected
• More health effects from the spread of tropical
diseases, heat waves, and so-called “natural
disasters”
• Loss of agricultural land in developing countries
• Disappearance of ecosystems that are unable to
migrate
5/24/2017
Cumulative carbon emissions, 1950-1996
15 ,715
C hina
11 ,651
Germ any
8,504
J apan
7,415
Unite d Kingdom
India
4,235
C an ada
4,054
2,331
So uth Africa
Mex ico
2,118
Aus tralia
2,080
1,557
Braz il
1,361
Ko re a, Rep.
96 6
Indon es ia
50 ,795
Unite d State s
0
10 ,000
20 ,000
30 ,000
40 ,000
Million tons o f carbon
Data Source: Marland et al, 1999. Carbon Dioxide Information Analysis Center.
50 ,000
60 ,000
Per capita emissions of carbon from
industrial sources, 1996
4.63
Aus tralia
2.91
Rus s ian Fe de ratio n
2.87
Germ any
2.59
Unite d Kingdom
2.54
J apan
2.46
Ko re a, Rep.
2.10
Ukra ine
1.88
So uth Africa
1.02
Mex ico
0.76
C hina
0.46
Braz il
Indon es ia
0.33
India
0.29
5.37
Unite d State s
0
1
2
3
Thous and tons of carbon
Data Source: Marland et al, 1999. Carbon Dioxide Information Analysis Center.
4
5
6
Vehicle numbers are rising dramatically
700
Cars
600
Buses and Trucks
500
400
300
200
100
0
1945
1955
1965
1975
1985
1995
Motor vehicle use is highest in developed
countries
United States
749.7
Japan
519
Europe
269.6
96.6
Brazil
South America
88.3
Hong Kong
81
Africa
22.4
China
7.9
India
6.7
0
(Motor Vehicles Per 1,000 Persons)
100
200
300
400
500
600
700
800
Success story:
CFC production has fallen sharply
1,200
Industrialized Countries
Developing Countries
1,000
800
600
400
200
0
1986
1989
1990
1991
1992
1993
1994
1995
How Much Arable Land is There
• Only 12% of the world soils are arable
• 26% is for pastures
• 31% for forests
World Agricultural Land Distribution
• Latin America, Sub-Saharan Africa and the
former Soviet Union have the most agricultural
land
• Europe (71%), South Asia (73%) and Southeast
Asia (47%) have highest percentage of total land
as agricultural land
• 70% of South Asia and Southeast Asia
agricultural land is the most intensive
Increased resource use for increased
crop production
•
•
•
•
•
•
Introduction of new crops
Mechanization
New and improved varieties
Inorganic fertilizers
Irrigation
Pesticides
(million metric tons)
More fertilizer: More food
Africa
Asia
South and Central America
Europe
North America
Oceania
World
160
140
120
100
80
60
40
20
0
1961
1966
1971
1976
1981
1986
1991
Food Supply Increasingly Relies on
Irrigation
Irrigated Soils Today
•
•
•
•
15% of the arable soils
Twice as productive as rain-fed soils
Produce a third of the world’s food
Subject to salinization in semi-arid environments
Are These Practices Sustainable?
What are the impacts of
• Land Degradation
• Energy
• Pesticides
• Genetically Uniform Crops
Land Degradation
• 15% of total world soils (1964 Mha of 13,077 Mha) lost
to soil degradation in the last 45 years
• 38% of cropland; 21% of pasture; 18% of forests
resulting in 13% loss in productivity for croplands
• Most of this lost is due to wind and water erosion (1725
Mha)
• Nutrient loss (135 Mha)
• Salinity (77 Mha)
Human-Induced Degradation
• 35% attributed to overgrazing
• 28% attributed to agricultural-related
management
• 29% attributed to deforestation
Degraded Soil Means Less Food
World Totals
(million hectares)
Vegetation Removal
Overexploitation
Overgrazing
Agricultural Activities
Industrial and
Bioindustrial
579
133
679
522
23
Forest Loss Is Severe in the Tropics
Many of Earth’s Forests Have Been
Cleared or Degraded
Amazon Deforestation Remains High
Energy
• In past, 5 to 10% of the final value of the crop
• Today, 50% of the final value of the crop
• Modern US agriculture puts in 80 times as much
energy per kilogram of rice as traditional Asian
practices with only a 4.5 fold increase in
production
• Even so, this is still only 3 to 5% of energy used
to get your food on the shelf
Pesticides
• Used extensively today
• Estimated crop losses to pests are 30% today
with pesticides and could be twice as much
without pesticides
• Can cause serious environmental pollution
• Pests are building up resistance
• Problems approached through IPM and Plant
Biotechnology
Genetically Uniform Crops
• Advantages: uniform quality and harvest date
• Disadvantages: loss of important germplasm;
narrower ecosystem more susceptible to
catastrophic damages from environmental
stress, disease and pests
How Much Are Nature’s Services Worth?
Global GNP
(US $18 trillion)
Ecosystem Services
(US $33 trillion)