November 5, 2008
a. What are the positive and negative effects of the agricultural "green revolution"? How were these results achieved and what were the tradeoffs?
Describe the differences between industrial agriculture and high intensity ag?
b. What are the main environmental impacts of agriculture?
one is - loss of soil and degradation of natural capital
Called the largest environmental impact of humans.
a. tradeoffs between physical quantities
water, land, soil, energy, biodiversity
example: water can be used to generate hydropower or irrigate crops
b. tradeoff between the quality of the resources available
use of a resource causes degrades the resource even while leaving the total nearly constant
example: energy degraded to heat (2nd Law of Thermo)
example: using a stream as part of sewage treatment increases the temperature
c. tradeoffs between efficiency of use
more water availability at the cost of energy use
example: deeper wells require more electricity
more power and more rapid resource use have associated problems
example: pollution from inefficiencies
example: complex interactions (land cleared for ag results in changing regional climate and water availability - Amazon positive feedback example)
d. tradeoffs between types of capital
human, built, financial, natural
example: types of farming and capital employed
Figure ?
subsistence high human effort
pre-industrial high human effort
some financial capital for equipment and animals
industrial high financial -equipment,fertilizer, energy for irrigation and traction
high natural - land
low human effort
intensive medium to high human effort and skill
medium to high financial for seeds and equipment
low land use (per capita)
d. because it can be described in terms of capital it is usually consider this as an "economic" activity
doesn't meet the simple definition of when markets work
resources are unique - may have non-dollar values
imperfect information - uncertainty is the rule not the exception
discount rate for the use today vs. saving for tomorrow is not known (multi-generational choice - see the Stern report from Britain)
http://news.bbc.co.uk/2/hi/business/6093396.stm
heavy externalities for all resource exploitation (especially as rates rise)
Upper Klamath Lake
committed 2x the amount of water in a good year
droughts and climate cycles
original approach was to drain parts of the lake
canals
levees - about 1/2 of the lake
land use
increased farming - non-point
decreased marshes
decrease of a water quality in the lake
3. toxic algae in water supplies
recent increase in outbreaks of algae in reservoirs
some contain toxins (liver and neuro)
strategy to protect public health
monitor lakes
base on cell counts or toxic assays
close to drinking, swimming and other forms of contact
linked to pollution (P, N, Fe)
examples:
Oregon
Diamond Lake - ecosystem problem (tui chub, eats zooplankton, releases algae from control)
Anabaena - toxins
first detected by dog sickness
exposure to children is critical (because of their behaviors)
to the extent that even boating is hazardous
poisoned the whole lake
Irongate and Copco - Microcystis
China - estimated 40% of the people have liver damage from water pollution
S. Africa -double whammy
ground waters are polluted
building surface reservoirs that may have algal problems