lecture note 18 for BGYB50

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Department
Biological Sciences
Course
BIOC50H3
Professor
Herbert Kronzucker
Semester
Winter

Description
LECTURE 18: - 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 significantly www.notesolution.com - Currently, based upon North American food consumption habits, the carrying capacity for the human population is less than 2.5 x 109 people - Breeding and biotechnology must produce further yield increases and increased stress resistance of crops (e.g. global rice production will have to increase by ~1.7-fold in the next 30 yrs.; this will be very difficult to achieve, given than current crop cultivars are already near physiological yield limits) - The potential of alternative, non-grain, foods needs to be explored (e.g. legume species, such as the winged bean, or insects, such as “Mopani” in Africa) - The new topic: The balance of competition and coexistence. Competition is one of the most important forces underlying the workings of the universe (that’s what the professor thinks anyway, so it’s best for students to think exactly the same!!), and is key to understanding the regulation of population growth….much more on this in lecture 19 www.notesolution.comLECTURE 18: - 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 10 tyr, enough to feed the worlds 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 13 of the global population inc
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