Some observers like to see Easter Island as a metaphor for the modern world. However, it is important to be aware of the differences. The first point, as has been emphasized already, is that societies of the Easter Island type do not necessarily have a dramatic decline. In the case of Easter Island, the civilization was ‘‘unlucky’’ to be on an island where the main resource was very slow growing. If the resource had been faster growing, then the boom – and-bust cycle probably would have been avoided, as it was in most of Polynesia. Therefore, even if Earth as a whole could be viewed as Easter Island writ large, there would no presumption about any inevitability of the imminent decline and fall of modern civilization.
On the other hand, Easter Island should not be viewed as an isolated case. As modern archaeology has made increasing use of sophisticated scientific methods, it has become increasingly clear that resource degradation has played an important role in the rise and fall of many civilizations. The truly unique feature of Easter Island was its isolation, which prevented migration as a response to resource degradation. In other parts of the world, overshooting population and resource degradation have led to substantial out-migration that mitigated, but did not eliminate, the population losses and the cultural losses associated with the boom-and-bust cycle. The lesson here is that resource management is very difficult, especially in conditions approaching open access, and overshooting is a genuine concern. This applies to the modern world just as it did to Easter Island. Thus, for example, major fisheries, major wildlife resources, and major forest resources around the world have been significantly compromised already. It is quite possible that various populations around the world, especially in areas with high population growth, such as Africa and parts of the Middle East, are on an overshooting trajectory.
Another lesson to be drawn from Easter Island concerns the danger of making simple linear projections based on a short time series. If an Easter Islander had, in the year 1300, extrapolated trends in population and real income based on the previous few centuries, that person would have failed to anticipate the ‘‘turning point’’ in population and real income that was coming. It is a characteristic of resource systems and predator-prey systems more broadly that cyclical patterns are common.
Even the two centuries of remarkable economic performance that have occurred in the time since Malthus should not encourage complacency about avoiding future Malthusian adjustment, especially if major renewable resource stocks (fish, forests, and soil) continue to decline. The world’s current population growth rate is about 1.3% per year, significantly lower than its peak of 2.2% (reached in 1963), but still high by historical standards. Current population growth rates imply a population doubling in just over 50 years. Current resource stocks, even if degradation could be slowed or halted, would have a hard time supporting such a population at anything like current levels of real income, even adjusting for likely technological improvements over the next 50 years. A subsequent doubling in the latter half of the 21st century would seem completely infeasible. Therefore, it seems that population growth will have to fall dramatically from current levels over the next 100 years. Whether this is achieved through a benign demographic transition or through the more unpleasant Malthusian mechanisms of disease, famine, and violent conflict is still very much an open question at this stage.
SEE ALSO THE FOLLOWING ARTICLES
Biomass Resource Assessment • Depletion and Valuation of Energy Resources • Ecological Footprints and Energy • Ecological Risk Assessment Applied to Energy Development • Ecosystem Health: Energy Indicators • Population Growth and Energy • Sociopolitical Collapse, Energy and
Bahn, P., and Flenley, J. (1992). “Easter Island, Earth Island.’’ Thames and Hudson, London.
Brander, J. A., and Taylor, M. S. (1998). The simple economics of Easter Island: A Ricardo-Malthus model of renewable resource use. Am. Econ. Rev. 88(1), 119-138.
Clark, C. W. (1990). ‘‘Mathematical Bioeconomics, The Optimal Management of Renewable Resources.’’ 2nd ed. Wiley, New York.
Dark, K. R. (1995). ‘‘Theoretical Archaeology.’’ Cornell University Press, Ithaca, N. Y.
Lotka, A. J. (1925). ‘‘Elements of Physical Biology.’’ Williams & Wilkins, Baltimore.
Malthus, T. R. (1798). ‘‘An Essay on the Theory of Population.’’ Oxford University Press, Oxford.
Ostrum, E. (1990). ‘‘Governing the Commons, The Evolution of Institutions for Collective Action.’’ Cambridge University Press, Cambridge.
von Daniken, E. (1970). ‘‘Chariots of the Gods? Unsolved Mysteries of the Past.’’ Putnam, New York.
1. Historical Air Pollution Episodes
[1] Arid Lands as a Key to Energy Stability
[2] The Desert Ecosystem
[3] Danger from Unbridled Development of Deserts
[4] Technological Milestones for Safe Development of Arid Zones
[5] Potential of Photovoltaic Technology
[6] Other Available Technologies
[7] Prospects and Conclusions
Glossary
desertification The conversion to true desert, as a result of human activities, of dryland located on the margin between desert and fertile regions.
ecosystem The totality of interdependent living organisms in a given physical environment.
megawatt (MW) Generally, a unit of power (= 106 W). When used in the context of a photovoltaic system, megawatt units refer to the maximum power output of the photovoltaic modules under specific (and somewhat artificial) test conditions. For this reason, the power ratings of photovoltaic and nonphotovoltaic power plants are not directly comparable.
performance ratio The annual energy output of a photovoltaic system, at a particular site, divided by the power rating of its photovoltaic modules. This figure of merit is, to a large extent, independent of the specific kind of photovoltaic modules employed.
photovoltaic module A panel assembled from a number of individual photovoltaic cells connected in series and parallel so as to provide the required voltage and current specifications of the module. Photovoltaic cells use the energy of incoming light to generate an electric current via the so-called photovoltaic effect. A single silicon photovoltaic cell, with typical dimensions 10 x 10 cm, would typically give a voltage of 0.5 V, and a current of 2 A when exposed to strong sunlight.
solar thermal A method of generating power from solar energy; in contrast to the photovoltaic method, solar
[8] Zebra cells have a higher operating voltage (2.58 vs 2.08 V).
2. Unlike sodium-sulfur cells, which are assembled in the charged state with highly reactive sodium that requires special handling conditions, Zebra cells can be assembled in the discharged state by blending common salt with nickel powder. (Note that state-of-the-art Zebra electrodes contain a
235 amu x 1.661 x 10 27kg/amu 1.602 x 10~13J 103 kg
[10] MeV 8.3 x 1016
The energy content of the U-235 isotope in natural uranium is therefore 0.0072 x 8.3 x 1016 Jt-1~5.7 x 1014Jt-1, and the energy in proven uranium reserves and ultimately recoverable resources is ~61 and 300 TW/year, respectively (1 TW/year = 31.5 EJ). At 10 TW, reserves and ultimate resources of fissionable uranium last only 6 and 30 years, respectively. However, the recoverable uranium ore may be underestimated due to lack of exploration incentives.
What about the seas? Japanese researchers propose harvesting dissolved uranium with organic particle beds immersed in flowing seawater. The oceans contain 3.2 x 10~6kg of dissolved uranium per cubic meter–a U-235 energy density of 1.8 million J/m3. Multiplying by the oceans’ huge volume (1.37 x 1018m3) gives large numbers: 4.4 billion tonnes of uranium and 80,000 TW/year in U-235. Even with 100% U-235 extraction, the volumetric flow rate to make reactor fuel at the 10-TW rate is five times the outflow of all Earth’s rivers, which is
1.2 x 106m3s-1. By comparison, the flow rate
[11] The simple dock, which is used only to a small extent, mostly by small operators and for temporary facilities. It depends on a relatively stable water level. The trucks dump directly into the barges or into a fixed chute.
2. The stationary-chute system has declined in popularity; it is relatively economical and has the same disadvantages as the simple dock system (sensitive to water level fluctuations).
3. The elevating-boom system is commonly used; it is very flexible and adjustable to variations in water levels. It can handle high capacities. The common features of this system found in most plants are the hinged boom, the pantograph trim chute, and the extensive dock area.
4. The spar-barge system is suitable for rivers with fluctuating levels. It has two essential components: the floating spar barge and the shuttle. The floating spar-barge (as floating dock) contains the loading boom and the barge-positioning equipment. The shuttle or retracting loading belt leads to the spar – barge.
[12] Cross-belt samplers (sweep arm or hammer samplers) sweep a cross section of the coal on the
[13] Removing the hot coal and using it immediately; if it is too hot for the transport equipment, it should be cooled first.
2. Removing the hot coal, cooling it by spreading into thin layers, and repiling and recompacting it; the coal can be left overnight to cool or can be sprayed with water. However, wet coal is difficult to handle.
[14] Excluding pedestrians and mobile equipment from stockpiles thought to be prone to flowslides or from coal piles with modified characteristics, particularly in the week after heavy rain or placement of wet coal.
2. Minimizing stockpile height during the rainy season; in case of busy shipping schedules and heavy rain, access roads should be closed to
[15] Consider the production and use of energy as means to certain ends, not as goals in and of themselves. Remember always that, given time and the capital for adjustment, energy is a largely substitutable input in the provision of most goods and services.
2. Application of technical ingenuity and institutional innovation can greatly facilitate energy options.
3. Energy decisions, like other investment decisions, should be made using clear signals of comparative total long-run costs, marginal costs, and cost trends.
4. It is important to correct distorted or inadequate market signals with policy instruments; otherwise, external costs can be ignored and resources can be squandered. This correction includes internalizing in energy price and/or regulation, to the extent possible, the national security, human health, and environmental costs attributable to energy.
[16] First and foremost, that energy conservation worked. Nothing contributed more to the improved American energy situation than energy efficiency. By the late 1980s, the United States used little more energy than in 1973, yet it produced 40% more goods and services. According to one estimate,
[17] Lack of leadership. Whereas an energy consumer can make short-term adjustments to save energy (driving slower, driving fewer miles and traveling less, adjusting the thermostat, or turning off lights), these mostly have the unpopular effect (other than saving money) of curtailing the very energy services that we seek. Sadly, such heroic shortterm curtailment measures are too often posed as the essence of conservation rather than emergency measures. On national television, President Carter
[18] The Physical Principle of Energy Conservation
FIGURE 4 Approximate zones of biological effects and ranges of typical concentrations of oil hydrocarbons (mainly aromatic) in seawater (top) and bottom sediments (bottom). Zones: 1, pelagic areas (open waters); 2, coastal and littoral areas; 3, estuaries, bays, and other shallow semiclosed areas; 4, areas of local pollution, including oil spills.
bottom sediments. These ranges can be roughly considered as the limits of maximum permissible (safe) concentrations of oil hydrocarbons dissolved in seawater and accumulated in bottom sediments, respectively.
[20] Mechanical means (booms, skimmers, etc.) for
collection and removal of oil from both the sea
surface and inshore habitats.
2. Burning of spilled oil at the site.
[21] Introduction
2. Basics of Decomposition Analysis
3. Methodology and Related Issues
4. Application and Related Issues
5. Conclusion
Glossary
aggregate energy intensity The ratio of total energy use to total output measured at an aggregate level, such as industrywide and economywide. decomposition technique The technique of decomposing variations in an aggregate over time or between two countries into components associated with some predefined factors.
Divisia index A weighted sum of growth rates, where the weights are the components’ shares in total value, given in the form of a line integral. energy intensity The amount of energy use per unit of output or activity, measured at the sectoral or activity level. gross domestic product (GDP) A measure of the total flow of goods and services produced by the economy during a particular time period, normally 1 year. index number A single number that gives the average value of a set of related items, expressed as a percentage of their value at some base period.
Laspeyres index An index number that measures the change in some aspect of a group of items over time, using weights based on values in some base year. structure change A change in the shares or composition of some attribute, such as sector output in industrial production and fuel share in energy use.
This article discusses the decomposition techniques formulated using concepts similar to index numbers in economics and statistics. They have been called the index decomposition analysis. Approximately 200 energy and energy-related studies have been reported since 1978. Of these, slightly less than 20%
[22] Agriculture and Urbanization
[23] Competition for Energy Resources
[24] Wood Energy
[25] Wind and Water Energy
[26] The Transition to Coal Energy
[27] Steam Power
[28] Steam Engines and Transportation
[29] Petroleum
[30] Electrical Power
[31] Energy flow and Industrial Momentum Glossary
agricultural revolution The period prior to England’s industrial revolution, when significant improvements in agricultural production were achieved through changes in free labor, land reform, technological innovation, and proto-industrial output. capitalism A socioeconomic and political system in which private investors, rather than states, control trade and industry for profit.
industry Economic activity concerned with processing raw materials and producing large volumes of consistently manufactured goods, with maximum fuel exploitation. industrial revolution The period of technological innovation and mechanized development that gathered momentum in 18th-century Britain; fuel shortages and rising population pressures, with nation-states growing in power and competing for energy, led to dramatic improvements in energy technology, manufacture, and agriculture and to massive increases in the volume of international trade. plague Referred to as the Black Death, or Bubonic Plague, which killed one-third the population of England and Europe from the mid-14th century until around 1500; millions of people perished, and commerce, government, energy production, and industry waned as farms were abandoned and cities emptied. proto-industry Supplemented agricultural income via the production of handcrafted work; this piecework was
[32] The Global Energy Balance
