De Aarde 2

'THERMODYNAMICSAND THE SUSTAINABILITY OF FOOD PRODUCTION
by Jay Hanson
revised 4/12/97

All matter and energy in the universe are subject to the Laws of Thermodynamics. In the discipline of Ecological Economics, systems are delimited so that they are meaningful to our economy. What does thermodynamics have to do with the sustainability of food production?
Thermodynamic potential is a measure of a system's capacity to perform work. The two essential forms of stored thermodynamic potential are "energy" (e.g., a barrel of oil) and "order" (e.g., clean drinking water and deep topsoil). [1]
"Entropy" is a measure of the unavailability of energy: the entropy of oil increases as it burns. Entropy can also be thought of as a measure of disorder in a system: polluted water that reduces crop yield has higher entropy than the same water unpolluted, and the entropy of topsoil increases when it erodes, is waterlogged, or is degraded by irrigation that "inevitably leads to the salinization of soils and waters." [2] [3] Increasing entropy in our food system is reducing the potential of the system to do work (produce food).
Sustainable systems are "circular" (outputs become inputs)—all linear physical systems must eventually end. [4] Modern agriculture is increasing entropy in both its sources (e.g., energy, soil, and ground water) and its sinks (e.g., water, soil, and atmosphere). Thus, modern agriculture is not circular—it can not be sustained.
Consider one of the most important limiting variables—energy. [5] Food grains produced with modern, high-yield methods (including packaging and delivery) now contain between four and ten calories of fossil fuel for every calorie of solar energy. [6] In the 70s, it was estimated that about four percent of the nation's energy budget was used to grow food, while about 10 to 13 percent was needed to put it on our plates. [7]
There is NO substitute for energy. Although the economy treats energy just like any other resource, it is NOT like any other resource. Energy is the precondition for ALL other resources and oil is the most important form of energy we use, making up about 38 percent of the world energy supply.
NO other energy source equals oil's intrinsic qualities of extractablility, transportability, versatility and cost. These are the qualities that enabled oil to take over from coal as the front-line energy source in the industrialized world in the middle of this century, and they are as relevant today as they were then.
40 years ago, geologist M. King Hubbert developed a method for projecting future oil production and predicted that oil production in the lower-48 states would peak about 1970. These predictions have proved to be remarkably accurate. Both total and peak yields have risen slightly compared to Hubbert's original estimate, but the timing of the peak and the general downward trend of production were correct. [8]
In March of 1996, World Resources Institute published a report that stated:
"Two important conclusions emerge from this discussion. First, if growth in world demand continues at a modest 2 percent per year, production could begin declining as soon as the year 2000. Second, even enormous (and unlikely) increases in [estimated ultimately recoverable] oil buy the world little more than another decade (from 2007 to 2018). In short, unless growth in world oil demand is sharply lower than generally projected, world oil production will probably begin its long-term decline soon—and certainly within the next two decades." [9]
Well, so much for oil! Should we be alarmed? YES! Modern agriculture—indeed, all of modern civilization—requires massive, uninterrupted flows of oil-based energy. For example, the International Energy Agency projects that world oil demand will rise from the current 68 million barrels per day to around 76 million b/d in year the 2000 and 94 million b/d in 2010. [10] What will happen when demand for oil exceeds maximum possible production?
To really understand the underlying causes and implications of oil depletion, one must stop thinking of the "dollar cost" of oil, and take a look at the "energy cost" of oil. We note that the energy cost of domestic oil has risen dramatically since 1975. [11] As oil becomes harder and harder to find and get out of the ground, more and more energy is required to recover each barrel. In other words, the increasing energy cost of energy is due to increasing entropy (disorder) in our biosphere.
Optimists tend to assume that the "quality" (e.g., liquid vs. solid) of energy we use is not significant, that an infinite amount of social capital is available to search for and produce energy, and that an infinite flow of solar energy is available for human use. Realists know that none of these assumptions is true.
In fact, ALL alternative methods of energy production require oil-based energy inputs and are subject to the same inevitable increases in entropy. Thus, there is NO solution to the energy (entropy or disorder) problem, and the worldwide energy-food crisis is inevitable.
When we can no longer subsidize modern agriculture with massive fossil energy inputs (oil-based pesticides and fertilizers, machine fuel, packaging, distribution, etc.), yields will drop to below what they were before the Green Revolution! [12] Moreover, billions of people could die this coming century when the U.S. is no longer able to export food [13] and mass starvation sweeps the Earth. [14]
Is there nothing we can do?
We could lessen human suffering if all the people of Earth cooperated for the common good. But as long as political systems serve only as corporate errand boys, we're dead.'

Lees verder: http://dieoff.org/page65.htm