Transcript 2. The Changing Global Environment

2. The Changing Global
Environment
Geological Base; Climate & Climate
Change; Water; Human Impacts on
Plants & Animals; Food Resources
Figure 2.2, Plate Tectonics
Figure 2.3, Global Tectonic Plates
Geology & Human Settlement: A Restless Earth
• Plate Tectonics/Continental Drift
• Break-up of Africa centered supercontinent Pangaea c. 250 million yrs Before
Present (BP)
• Formation of Tethys Sea
• Removal of Australia from main evolutionary line in Pangaea and around Tethys Sea
• Removal and return of India to create Himalayan Mountain Range
• Formation of major fold mountain ranges along leading edges of North and South
American Plates
• At human scale, problems of earthquakes and volcanic activity along plate
boundaries
• Plate Tectonic Theory confirms Evolutionary Theory
• Collapse of Reptiles as dominant species c. 65 million years BP, probably because of
impact of asteroid in Yucatan peninsula
Figure 2.3, Global Tectonic Plates
Figure 2.7, Global Earthquakes and Volcanoes
Climate Change
• Climate change: natural, anthropogenic, or both?
• Glacial, interglacial, & interstadial climates
• Natural change--a historic pattern of 400 to 600 years interval for the past 2,000
years?
• Evidence for change (the church & wine production in Europe).
• Shift in North Atlantic Drift
• Rice cultivation in China
• Deforestation in Europe
• Recent anthropogenic change
• Burning hydrocarbons produces carbon dioxide. CO2 main contributor to Global
Warming (Table 2.1)
• Large scale CO2 production began late 1770s w/Industrial Revolution & coal
burning
• Modern CO2 production largely from automobile fleet
• Only EU has attempted to mitigate automobile CO2 output
Figure 2.11: Global Pressure Systems
Climate
• Planetary heat transfer from Equatorial to Polar regions
• Planet takes in more solar radiation between Tropics of
Cancer and Capricorn than it loses, loses more from Polar
regions than is coming in (see Fig. 2.1)
• Hot air and water masses move polewards, cold air and
water returns toward Equator
• Planetary heat transfer & us
• Warms west coasts of continental masses
• W. Europe main beneficiary
• Provided main power source (wind) for planetary movement
(ships) from late 1400s to mid-1800s
Table 2.1 (3rd edn): the World’s Major CO2 Polluters
Table 2.1 (4th edn): the World’s Major CO2 Polluters
Water on Earth: A Scarce & Polluted Resource
• Only 3% of world’s water is fresh water, most of it is ice, & there is
rarely enough where humans want it!
• Except when it floods. Floods cause more fatalities than any other
natural disaster. Too many people live in flood prone regions (e.g.
Bangladesh)
• Much water is polluted & runoff has been increased by deforestation
• Water more valuable than oil
• Most destructive use of water is in agriculture (evaporation)
• Use in closed systems (water for sewage disposal, washing etc.)
allows recycling (tho at some cost)
• When there is water policy it tends to underprice water
• Texas had no comprehensive water plan until Senate Bill 2 took effect
9/1/2001
Human Impacts on Plants & Animals
• For most of human history we collected and hunted food
• C. 20,000 BP Agricultural Revolution (AR) improved food supply, but
still erratic. Protein, inputs dropped. AR encouraged human crowding
(bad for health-poor waste disposal etc.) Food surplus made urban life
& civilization possible, allowed division of labor, elites
• Population rose rapidly, then leveled off
• AR Plants chosen for productivity, ease of cultivation
• Animal resources added later to do work, for protein, & for fiber
• Organic Society marked by 3Fs. Food, Fiber, Fuel all grown in
Organic Society
• Land resources allocated between 3Fs according to population
pressure, environmental needs etc.
• Humans lived on, at best, c. 3 million cals. each per year
Figure 2.19: World Bioregions
Food resources: environment, diversity, globalization
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Industrial Revolution c. 200 years BP transformed human societies and economies
Better transport made food supply much more reliable
Better public health began inexorable increase in human life expectancy
Fossil fuel inputs took fuel out of 3F equation, then fiber, thus more land for food
Population skyrocketed, in part because of more reliable food supply (remember that
deaths drop before births in classical version of Demographic Transition-DR)
Global population currently showing signs of reduced rates of increase (i.e. reaching
stage 3 of DR)
Fossil fuel inputs to food now immense in developed world (10 calories in, 1 cal
vegetable energy out: 10 cals vegetable energy in, 1 cal beef protein out)
Calorie consumption per head in America now c. 100 million calories per year
Rest of developed world much lower (Germany c. 40, Japan below 30)
LDCs starting to catch up very quickly in consumption (remember increase in
China’s CO2 output)
World Population & Grain Production
Grain for people vs grain for biofuels
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World grain supply only just keeping pace w/world population growth
North America and EU are world’s only large scale exporters of grain
Grain in NA, EU requires high fossil energy inputs
Public policy in US has reduced world grain supply by diverting corn
to biofuel production, causing sharp rises in grain prices
• Biofuels from food grains actually have negative impact (more
calories in than calories out) as well as other negatives (increase in
greenhouse gasses)
The next 50 years in energy (“this is your life” part 1)
• Serious and accelerating climate change (now looks fundamentally
irreversible, although better public policy could reduce impact)
• “Short” term energy crisis (likely to see 30 years of steadily rising
prices and accelerating demands for efficiencies in usage of fossil
fuels and electricity, most of which still comes from fossil fuels)
• Some solutions unlikely if examined closely-clean coal for example.
World has coal in abundance but generating electricity with coal
results in much higher CO2 output per unit energy generated than
using natural gas. China, India, building huge # new coal plants
• Long term energy stability, assuming renewed investments in nuclear
power, substantial investment in wind power, ramped up research into
alternate fuels
• Main shortfalls will be in liquid hydrocarbons for air transport and as
raw materials for plastics
The next 50 years in the environment (“this is your
life” part 2)
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Global warming, global warming, global warming
Plausible rise in hurricane/cyclone frequency
Massive rise in flood related deaths in LDCs
Serious threats to coastal cities around world
What is currently happening to New Orleans will become
commonplace
• Capital cost of defending coastal cities will necessitate huge
increases in public spending or abandonment of such cities
• Potable water will become substantially more expensive,
not least as salt water from rising sea levels penetrates
coastal aquifers
Books worth reading
• Kenneth S. Deffeyes, 2005. Beyond Oil: the View
from Hubbert’s Peak. NY: Hill & Wang
• Bruce Podobnik, 2006. Global Energy Shifts:
Fostering Sustainability in a Turbulent Age.
Philadelphia: Temple University Press
• Spencer W. Weart, 2003. The Discovery of Global
Warming. Cambridge: Harvard University Press