As the
oceans warm, they are less able to absorb CO2. Present-day society is locked
into four positive feedback loops which need to be broken:
economic growth which feeds on itself, population growth which
feeds on itself, technological change which feeds on itself, and
a pattern of income inequality which seems to be self sustaining
and which tends to spur growth in the other three areas.
Ecological humanism must create an economy in which economic and
population growth is halted, technology is controlled, and gross
inequalities of income are done away with. —Victor
Furkiss,
THE FUTURE OF TECHNOLOGICAL CIVILIZATION
ECOLOGICAL
DEMOCRACY, by Roy Morrison;
South End Press, 1995; ISBN 0-89608-513-9
In 1992, Dr. Jeremy Leggett, a British scientist and scientific director of Greenpeace International's Atmosphere and Energy Campaign, outlined what may be called a "nightmare global warming scenario." This scenario was based on a projection of known, but as yet unquantified, biological feedback mechanisms identified by the Intergovernmental Panel on Climate Change (300 atmospheric scientists from forty countries).
This scenario is a plausible extrapolation from what is known: it reflects both the magnitude of the possible risks courted by industrial humanity, and the inadequacy of the global managerial perspective when circumstances go beyond what is viewed as industrially acceptable. However, even if this scenario is completely accurate, industrial managers can always point to enough uncertainty at each step to justify inaction.
Global warming is the result of the release into the atmosphere of "greenhouse gases," i.e., gases that are relatively transparent to the passage of energetic short-wave solar radiation (sunlight) and, at the same time, reflect back much of the longer wave infrared (or heat) radiation generated when sunlight strikes the earth. The most significant greenhouse gas is CO:, which has been released into the atmosphere in huge quantities as a by-product of burning fossil fuels in automobiles, power plants, and industrial processes such as steel production, and by wood burned for fuel and forests burned for land-clearing. In 1950, 1.62 billion metric tons per year of carbon (gigatons carbon or GTC) were released from burning fossil fuels; by 1991, this figure had increased to 5.854 billion tons per year.
To get some sense of the significance of this number, we need to know that the preindustrial atmosphere contained an estimated 580 billion tons of carbon. Thus, we are now adding about 1 percent of the preindustrial carbon total to the atmosphere yearly. Current atmospheric carbon levels are 750 GTC, a 29 percent increase from preindustrial levels. In only thirty-two years since 1959, when continuous record keeping of atmospheric carbon dioxide began, concentrations have increased 12 percent from 316 parts per million (.0316 percent) to 355 parts per million (.0355 percent). Other greenhouse gases include methane (CH4), a product of natural decay and fermentation released in large quantities from concentrated livestock production, and the chlorofluorocarbons (CFCs) that are also responsible for the destruction of the ozone layer.
The precise global dynamics and possible effects, both long-and short-term, of huge increases in greenhouse gases are unclear. There is a natural cycle that keeps CO2 concentrations relatively balanced. Huge amounts of CO2 are dissolved in the oceans, 39,000 GTC with about 90 GTC exchanged each year between atmosphere and ocean. (CO2 in water forms carbonic acid-this is why steam heating condensate pipes often corrode unless the boiler water is deaerated.) Huge amounts of carbon are also locked up in submarine methane hydrates, ice-like solids made up of water crystals and trapped methane gas, on the Arctic continental shelf.
Carbon is also found in the bodies of all living things, from giant redwoods to microscopic creatures (an estimated 750 GTC in land plants and 1,500 GTC in soils; annually 100 GTC is exchanged between the atmosphere and land plants.) The normal carbon-based system includes the use of CO2 by plants, which release oxygen as a by-product that is then used for animal respiration (which, in turn, yields CO2 as its by-product). The carbon taken up in the bodies of living creatures is also released in the form of methane as they die and decay.
Atmospheric scientists argue that climate stability can likely be sustained if levels of human CO2 production are somewhat below the emission levels seen in the 1950s. At present rates, by the middle of the 21st century, most climate scientists predict substantial increases in global temperature.
How significant these increases will be, and the nature of their impact, is the question. Jeremy Leggett warns that such global warming may disturb major sinks for carbon in Arctic tundra and, through a complex series of interactions, result in runaway warming that would continue even if human CO2 and all other greenhouse gas emissions dropped to zero.
Leggett's "putative" logical chain of events includes:
As the
oceans warm, they are less able to absorb CO2.
Warming
oceans are more thermally stable. This stability reduces the
circulation of nutrients and decreases the biomass of the
photoplankton, thus further damaging the ability to absorb CO2.
Ultraviolet radiation from the damaged ozone layer, particularly
severe in polar regions, further damages the photoplankton. The
net ecosystem balance between respiration (CO2 emitted) and
photosynthesis (CO2 used) now tilts toward respiration, and more
CO2 is released into the atmosphere.
As the
temperature rises, Arctic tundra melts and releases huge amounts
of methane. Under certain conditions, wet, flooded soils can
release 100 times more methane than dry soils.
At this
point, drought in many areas from warming and associated climatic
changes further retards photosynthesis.
Changes
in the chemistry of the atmosphere deplete the cleansing hydroxyl
reservoir that oxidizes methane and other greenhouse gases.
Ozone
in the troposphere, a greenhouse gas at lower levels of the
atmosphere, is increased as a result of carbon monoxide and
nitrous oxide from growing automobile exhaust.
The
Arctic ice cover begins to thin and retreat. This thinning
reduces the albedo (the net reflectivity of the planet), thus
leading to further warming.
Finally, huge amounts of methane trapped in the Arctic
continental shelf in the form of methane hydrates are released
from under the permafrost and in shallow Arctic waters.
Leggett concludes, "In emergency session the UN brings in sweeping measures for world-wide greenhouse gas emission reductions. But it is too late. A runaway greenhouse effect has been generated."
This chain of events is a dark possibility. It is not a prediction. It does make clear that industrial civilization has put into question not just the prospects for human society, but planetary processes hitherto the domain of natural rhythms and geological time. Industrialism is betting that its resolute commitment to continuous growth can somehow be managed to avoid catastrophic consequences.
The world has 4,000 GTC in proven fossil fuel reserves; we cannot decide their future use, the production of further CFCs, and the mass burning and clear-cutting of forests on the basis of maximizing industrial production and consumption, profits and power. Industrial civilization entertains a hideous risk if it continues each year to pour 5.8 billion tons or more of carbon into the atmosphere. Whether industrialism's technocratic eschatologies are reassuringly exponential, cautiously logistic, or righteously catastrophic, social behavior, as well as the reality behind imperfect mathematical models, will determine the nature of alternative futures. [p.p. 109-112]
LONDON, Feb 21, 1996 (Reuter) - Global warming, acid rain and the hole in the ozone layer are joining forces in a deadly combination for fish and other life in lakes and streams, Canadian scientists reported on Wednesday.
The key, they said, was the amount of carbon dissolved in the water. Carbon absorbs ultraviolet radiation from the sun, and protects aquatic plants and animals from the dangerous solar rays being let through by the widening holes in the ozone layer.
But the researchers said global warming and acid rain were reducing carbon levels in lakes, thus wiping out what little protection the fish and the plants they depend on had.
Acid rain is caused when clouds pick up pollutants such as sulphur dioxide from factories and coal-burning power plants. The chemicals react and raise the acidity of the rain.
David Schindler, a biologist at the University of Alberta in Edmonton, and colleagues took measurements at several lakes in northwest Ontario over 20 years.
During this time, Schindler's group wrote in the science journal Nature, overall temperatures rose by 1.6 degrees C (1.9 degrees F), rainfall fell by 25 percent and "once-permanent streams became intermittent."
Carbon levels in the lakes fell by 15 to 20 percent, allowing radiation to penetrate 22 to 63 percent deeper.
In the lake with the highest acid levels, ultraviolet radiation penetration increased from a third of a metre (one foot) to more than 2.8 metres (nine feet).
"An 80 percent decline in carbon, as in acidified lakes, would cause the depth of the...UV-B...to increase by over 400 percent," they added.
Radiation is as dangerous to fish and seaweed as it is to people and their crops. For example, trout get sunburn, are more prone to fungal infections and in general die sooner when exposed to slightly higher radiation levels.
Extra radiation could become one more stress that pushed a species over the edge into extinction, they said.
"Overall, we estimate that about 140,000 of the nearly 700,000 lakes in eastern Canada may have (carbon) concentrations low enough for UV-B penetration to be of concern," they said.