Agriculture Can We Feed The World?

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AgricultureCan We Feed The World?

• Grant R. Cramer
• Plant Biology 330
• Fall 2001

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Humanity has grown in numbers over time
7,000
6,000
5,000
4,000
Millions of people
3,000
2,000
1,000
0
0
500
1000
1500
2000
2500
Year
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Global Population Continues to Rise
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Different Assumptions, Different Projections
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Fertility Declines, Real and Projected
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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

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More Children Are Attending School
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More Adults Can Read
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Yields Are Up, But Growth is Slowing
5
4
3
Yield (metric tons/hectare)
2
1
0
Wheat Yield
Rice Yield
Maize Yield
10
Yields Are Up, But Growth is Slowing
12
10
8
Increase in Yield
6
4
2
0
-2
Wheat
Paddy Rice
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Trends in Per Capita Food Production
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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)

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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

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Despite Gains, Millions Go Hungry
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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

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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

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Humans Can Affect the Climate and Influence
Agricultural Production

• Desertification in the Sahel
• Greenhouse Effect

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Global warming enhanced by emissions of man-made
gases
Source Climate Change, State of Knowledge,
OSTP, 1997
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Greenhouse gas warming
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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

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CO2 is building up in the atmosphere
Source Climate Change, State of Knowledge,
OSTP, 1997
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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/lawdo
me.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 9814,753-14,770. 1993.
Available http//cdiac.esd.ornl.gov/ftp/db1007/cm
eares.mon
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Earths temperature continues to rise rapidly
Source Climate Change, State of Knowledge,
OSTP, 1997
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Earth is projected to grow warmer
Source Univ. of East Anglia, IPCC
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The polar ice cap is melting
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Uncertainties still persist

• Timing and regional impacts
• The effects of increased cloudiness
• Uncertain health and ecological impacts
• Possible surprises from unanticipated effects

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More impacts of global warmingcan 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

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Cumulative carbon emissions, 1950-1996
Data Source Marland et al, 1999. Carbon Dioxide
Information Analysis Center.
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Per capita emissions of carbon from industrial
sources, 1996
Data Source Marland et al, 1999. Carbon Dioxide
Information Analysis Center.
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Vehicle numbers are rising dramatically
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Motor vehicle use is highest in developed
countries
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Success story CFC production has fallen sharply
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How Much Arable Land is There

• Only 12 of the world soils are arable
• 26 is for pastures
• 31 for forests

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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

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Increased resource use for increased crop
production

• Introduction of new crops
• Mechanization
• New and improved varieties
• Inorganic fertilizers
• Irrigation
• Pesticides

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More fertilizer More food
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Food Supply Increasingly Relies on Irrigation
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Irrigated Soils Today

• 15 of the arable soils
• Twice as productive as rain-fed soils
• Produce a third of the worlds food
• Subject to salinization in semi-arid environments

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Are These Practices Sustainable?

• What are the impacts of
• Land Degradation
• Energy
• Pesticides
• Genetically Uniform Crops

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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)

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Human-Induced Degradation

• 35 attributed to overgrazing
• 28 attributed to agricultural-related management
• 29 attributed to deforestation

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Degraded Soil Means Less Food
World Totals (million hectares) Vegetation
Removal 579 Overexploitation 133 Overgrazing 679
Agricultural Activities 522 Industrial and
Bioindustrial 23
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Forest Loss Is Severe in the Tropics
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Many of Earths Forests Have Been Cleared or
Degraded
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Amazon Deforestation Remains High
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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

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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

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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

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How Much Are Natures Services Worth?
Global GNP (US 18 trillion)
Ecosystem Services (US 33 trillion)