Natural Resources
& Societal Issues - A Geologic Perspective
William P.
Leeman
Department of
Geology & Geophysics
Rice
University
This will be a talk in
three parts - time allowing:
Geologic perspective -
how does a geologist look at the world?
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From space we see a Blue
Planet - unique in the abundance of water at its' surface, with a dynamic atmosphere.
<-- Click on the image for an expanded view.
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We know from distributions
of earthquakes and volcanoes that the outer portion of the solid
Earth is tectonically active and is subdivided into a number of
relatively rigid plates that slide around the globe - with consequent divergent, convergent, and sometimes simple transform (strike-slip) margins (schematic
diagram).
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The structure of the Earth can be subdivided into a brittle outer layer (lithosphere - on the order of 100 km thick), a thick relatively ductile mantle, and a dense core - the outer part of which is molten. By comparison, the other rocky planets in the solar system have been tectonically inactive for most of their history.
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New oceanic crust is being formed at divergent margins and older crust being consumed or under thrust at convergent margins.
Based on multifaceted geologic investigations by many people, the positions of most plates can be traced back through geologic time with a high degree of certainty. The plate motions can be recreated in animations to illustrate how varied was the face of the Earth through time.
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This brings us to time itself, or Geologic Time, which is immense - the Earth formed roughly 4.5 billion years ago and has been evolving ever since, albeit with some irregularities in rates and intensities. Events that are exciting to geologists seem hardly to be happening to the average person.
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Global climate variations through geologic time reflect oscillations in mean temperature, in part resulting from changing positions of continents and ocean circulation patterns; these, in turn, caused variations in sea level and in atmospheric CO2 content.
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Key
events/processes:
- Evolution of an atmosphere
- from predominantly CO2 to the present N2-O2 rich blend
- Creation of a hydrosphere
and the first seas
- Evolution of life
- Drift of the tectonic
plates
- Collisions of continents or
ocean crust and continents created volcanic
belts (e.g.,
Western
U.S.) and uplifts
and mountains (e.g., Himalayas)
- Rifting of plates created
new valleys and even ocean basins (e.g., Africa
& Atlantic)
These and related processes
resulted in magmatism, metamorphism, and ultimately in erosion and
sedimentation once there was a significant hydrosphere/atmosphere.
The distribution of major rock types in space and time constitutes
the Geologic Record.
Natural resources
Introduction and definitions
Types of resources
Renewable vs. non-renewable
(defining the system)
Geological controls on the
distribution of NRs
- Geologic time and the
dynamic Earth - continuous vs. punctuated evolution
- Primary processes -
plate tectonics paradigm
- Igneous, sedimentary,
metamorphic examples to tectonic setting/environment
Redistribution of the wealth: geography, climate, and other factors
Economic factors - what
determines value of a resource?
Water - controversies and politics
Water resources - statistics
Aquifers - supply, quality
- Water use and water
resources in the US (precipitation, US
use by area)
- Colorado
River drainage
basin (CAP, water
distribution,
climate
effects,
climate
record,
Tucson)
- Problems (e.g.,
flood
irrigation,
pivot
irrigation,
dams, desert
pools,
aggie
pools,
land
development,
urban
growth,
depletion)
Water issues in Texas
(mainly)
Global Issues (scarcity)
Paradigm shift in U.S.
Energy/fuel resources
Energy demands
Oil production
Predictions for future
supplies
Environmental
concerns
Alternative fuels - other fossil fuels (e.g., coal), nuclear energy, renewables (e.g.,
solar, geothermal)
Societal implications -
foreseeable problems
Long-term supply forecasts
(reserves)
Adding population growth to
the matrix
Rethinking resource
utilization (subtitutes, recycling, conservation)
International disputes
(e.g., Middle
East)
The changing water paradigm
20th century water resources development driven by economic growth ethic:
- Population growth (1.6 to 6.0 billions)
- Industrial development
- Expansion of irrigated
agriculture (50 to 250 Mhectares)
We now appropriate ~54%
of accessible runoff (70% by 2025?)
US: >80,000 dams and
reservoirs, 90,000 Mwatts of hydroelectric capacity, >15,000
wastewater treatment plants, over $400 billion spent
Lost: >60% of inland
wetlands, 50% of stream-miles polluted to some extent, many fish
runs decimated (e.g., Columbia R. salmon)
Late 20th century - shift toward new water ethic? Integrity of water resources and ecosystems, fair distributions, sustainability. Also influenced by high costs of maintaining traditional infrastructure, decreasin opportunities.
US per capita water use began to decrease around 1980, with large decreases in industrial use - result of changing economics, role of
'environmental movement'. Projections of global water withdrawals have decreased with time.
Future trends
- Fewer large water-works
projects
- Increased efficiency of
use - reallocation, recycling
- Shift away from
water-intensive industrial processes
- Residential
conservation
- Improvements in
agricultural technology, methods
- Economics and water
pricing structures
- Alternative supplies,
reclaimed wastewater, desalination
- Education, more
dependence on heterarchical (decentralized) management
Important water-related
issues:
- Water & human
health
- The status of large
dams: the end of an era?
- Conflict and
cooperation over fresh water
- Climate change and
water resources: what does the future hold?
- New water laws, new
water institutions
- Moving toward a
sustainable vision for the Earth's fresh water
Water brief
Small comets
and the debate over the origin of water on Earth (cf. evidence
for water on Mars)
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A night-view of the U.S. from the Space Shuttle presents a graphic image of population density distribution based on light emissions.
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References
P.H. Gleick (1998) The
World's Water: 1998-1999. Island Press, Washington, D.C.
Page created: 3 Mar 1999