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lecture note 18 for BGYB50


Biological Sciences
Course Code
Herbert Kronzucker

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- The ecological footprint analysis reveals that at least three planets Earth would required
to sustain the present human population at the resource consumption rates of North
Americans; a similar result emerges when food consumption habits alone are examined
(see below)
- Present world grain production: ~2 x 109 t/yr, enough to feed the world’s people (but:
inequitable distribution!); most important crops: rice, wheat, corn, potato
- Grain production has tripled since 1950, due to two “Green Revolutions (new crop
varieties, fertilizer use, pesticides, irrigation, additional cropland)
- However, per capita grain production has flattened out in recent years, and the human
population is presently consuming more grain than it is producing
- Present annual grain yield increases are less than 1/3 of the global population increase
- The WHO (World Health Organization) estimates that ~1.2 x 109 people are
chronically hungry, and some 40 x 106 die each year from hunger (equivalent to some
300 jumbo jets crashing, with no survivors)
- Each food item in North America has travelled an average of 2,100 km prior to being
consumed (the indirect costs of agriculture are enormous, in many cases requiring a
higher input of energy than is released in food consumption)
- Livestock presently consume ~38% of the world’s grain (more than 70% in North
America; there are ~1.3 x 109 cows, 1.7 x 109 sheep, 12 x 109 chickens globally)
- In addition to the problem of indirect crop consumption by consumption of livestock,
the conversion of crop lands to the production of biofuels aggravates the supply problem
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