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Coral reefs
The production of CaCO3 and other carbonates in the oceans is a relatively modest mechanism for fixation of C over the short term and one confined to the comparatively shallow waters of the continental slopes because of the dissolution of CaCO3, particularly beyond 1500-5000 meters (the calcite compensation depth) (Sundquist, 1985), in the open ocean. Estimates for the overall annual fixation of carbon in carbonates (0.11 Gt ) associated with the coral reefs (61.7 x 106 ha) of the world are about 2% or so of annual anthropogenic production (Kinsey, 1991). Coral reefs thus fix 1.78 t/C/ha/yr. It is further predicted that this figure could double in a time-frame of 100 years (Sundquist, 1985, Kinsey, 1991). Of the 20 x 106 t of organic C/yr. produced by coral reefs, 3 x 106 t remain in sediments, 15 x 106 t are exported to the ocean as detritus and 2 x 106 t are used by human harvest, (Kinsey, personal communication, 1991). Other annual carbonate-carbon deposition rates are likewise low, 0.0-0.37 Gt C (after subtraction of coral reef estimate (Kinsey, 1991)), continental shelves. Particulate carbonate flux to the deep oceans is around 0.42-1.18 Gt C (Sundquist, 1985). A further consideration is that precipitation of Ca as CaCO3 mentioned above, tends to lower the partial pressure of CO2 in seawater thus potentially driving this gas into the atmosphere to act as an agent for the liberation of Ca over the long term.
The residence time of Ca in the oceans is estimated as 8 x 106 years (Moore, 1983), furthermore the "basic equilibrium of the earth's crust" can be expressed by the following equation: CaSiO3 + CO2 <-> CaCO3 + SiO2. From this perspective, coral reefs are simply biological devices for slowly restructuring terrestrial limestone deposits over rather long time frames as oceanic sediments are moved onto emergent landforms and then returned to the sea.
The currently accepted annual CO2 production by degassing from volcanic sources is determined (Gerlach, 1991) by balancing calculations as (72.3-132.3) x 106 tons of carbon annually. An alternate indirect measurement estimate from Hawaii (Buddemeier and Puccetti, 1974) postulate 270 x 106 t./yr. Freyer (1979) estimates volcanism to be responsible for (100-500) x 106 tons carbon per year. Without such input some indications are (Gerlach, 1991a) that silicate weathering, carbonate deposition and organic burial could have stripped the atmospheric CO2 in 10,000 years. On this basis, coral reef carbonate fixation might have been somewhere between 40%-152% of pre-industrial (volcanic induced) carbon input to the atmosphere. A more recent estimate (Gerlach, 1991b) postulates (36-48) x 106 tons of carbon released annually from non-eruptive volcanic sources. This is an order of magnitude lower than previous estimates and coral reefs would be able to fix around 229%-300% of the resulting carbon annually. From this standpoint, volcanoes may have contributed about 35%-65% of the CO2 needed to balance the pre-industrial deficit. Estimates of CO2 released from recent volcanic eruptions do not support this low figure (Malling, Personal communication). There have been three major eruptions since 1800 (Tambora, Krakatau and Pinatubu) which have together discharged over 130 km3 of lava, ash etc. A further 60 known eruptions (approximately) have together produced around 150 km3 of material not to mention a number of marine events. All told, a conservative estimate places the material discharge at around 1.5 km3 per year from 1800 to date. Considering the median lower estimate for outgassing (Gerlach, 1991b) of 102.3 x 106 t C/yr, the combined discharge is unlikely to amount to less than 0.2-0.5 Gt C/yr (Malling, personal communication). Coral reefs might fix 31% of this annually. See chart 1.
Global climate: technical considerations
In a recent paper by C. Lorius et al (1990) the authors were able to account for a very high component of the temperature variance by knowledge of atmospheric CO2 and methane concentrations within air bubbles trapped in the ice spanning a period of some 150 k yr. and extending over two distinct glacial periods.
Since the CO2/CH4 component by itself accounted for such high proportion of the temperature variance (42%-65%) over the interglacial-glacial range of the last 150 kyr, this suggests that orbital forcing, although implicated in Quaternary glaciation cycles might not have been the primary mechanism. This leads to the hypothesis that it might be variation in green-house gases alone that primarily controls the glacial-interglacial response by directly determining temperature.
The current rate of increase in carbon emissions from fossil fuel burning is approximately 4.0 %-4.3% per year. This presently corresponds to a doubling time of around 18 years or so. The pre-industrial concentration of CO2 of 260-280 ppmv in 1800 is expected to double by around 2025. The present atmospheric concentration of CO2 is approximately 353 ppmv (1990) and growth is by given as 0.4% by Ashmore, 1990. At 1% annual growth (worst case analysis) the doubling time would be around 70 years or so. Recent data obtained from polar ice cores (Vostok) (Lorius et. al. 1990) show that over the last glacial - interglacial event, a period of some 150 k years, the mean global temperature shifted by some 6 deg. C and the CO2 concentrations showed a low of 170 ppmv to a high of 300 ppmv associated with glacial and interglacial conditions respectively. Multivariate statistical analysis on data from throughout this period associated 50%-65% of the temperature variability with variation in the concentrations of just two greenhouse gases, CO2 and CH4 (CH4 eventually oxidizes to water vapor and CO2). These historical data show that the warming induced by doubled CO2 concentrations was 3-4 deg. C. In the Lorius et. al. model, knowledge of CO2 and CH4 concentrations allows a close prediction of the resulting temperature but it does not tell us where these gases came from. The 150 kyr record shows two major CO2/CH4 pulses at about 18-8 kyr and 150-140 kyr as well as a number of intervening smaller events or spikes. Releases of the gases may have been initially induced by increased insolation and then re-inforced by alternate mechanisms (discussed below) or by what appear to be apparently non-systematic events resulting from increased volcanic activity. Yet another possibility involves the action of global processes which may themselves be independent of orbital changes. Unlike the oceans, the atmosphere closely approximates a homogenous reservoir over time scales of a few years in relation to CO2.
Biosphere driven climate cycle and global evolution model
On a geological time frame of tens of thousands to millions of years and in absence of a dominant human population the following simplified model might be proposed: starting with either a CO2 pulse or perhaps CH4 emissions (or both), a photosynthetic primary production response takes place which removes CO2 from the atmosphere (both on land, Tans et. al. 1990, and in the oceans, Williamson and Holligan 1990) leading to sequestering of carbon in organic and perhaps inorganic (CaCO3) form. This photosynthetic "draw-down" of CO2 may progressively reduce temperatures and eventually lead to glaciation. Massive movement of ice-sheets might in turn expose organic carbon deposits and lime-stone which weather and release CO2 to the atmosphere in the form of pulses of greater or lesser magnitude. The pulses may then have been followed by photosynthetic draw-down forming coal, peat, oil etc.
A further role in this process may be played by gas hydrates (mixtures of gas molecules, predominantly methane, caged in water) which are found in quantity within sediments on the ocean floor and under perma-frost to name two places. Glaciation at its height absorbs vast quantities of water promoting sea-level lowering. This may in turn trigger release of methane due to instabilities promoted in under-sea sediments leading to "submarine landslides". Under greenhouse conditions, the action of bacteria on organic-rich sediments may promote the formation of quantities of gas-hydrates. Greenhouse warming may also result in gas hydrate release due to temperature effects or permafrost flooding (Appenzeller 1991). The sequestering of water by ice at the glacial maxima might also lead to dryer conditions promoting fires in existing biomass and thereby favoring peat and forest bio-mass fires (Pulliam, 1991, personal communication). The present (October 1991) forest fires in Kalimantan are burning, in part, through a surface coal measure of some 20 x 106 t (Jakarta Post, p 4, Monday October 14 1991).
The mechanism for a scenario involving bio-sphere based draw-down of atmospheric CO2 may also be supported by the following line of reasoning. Some evidence (Woodward 1990) shows that certain C3 plants currently have the ability to respond continually to increased concentrations of CO2 by: 1) increasing photosynthetic activity by as much as 66% for a given light regime in response to a doubling of CO2 from 350 ppmv to 700 ppmv and 2) increasing leaf area index by as much as 95% for an arboreal canopy.
It is anticipated that if such a model as indicated above is correct, then investigation should reveal existing C3 flora with sufficient capacities to respond to CO2 increases by increasing primary productivity markedly above present levels. One might expect that C4 plants which are CO2 saturated at levels as low as 100-200 ppmv CO2 would be ideally adapted to icehouse conditions showing a tendency to be competitively dominant therein. It may be noted that most trees and plants with broad leaves are C3s, including some grasses, and C4s are generally grasses. It might also be anticipated that some of the productivity attributed to the "green revolution" in fact should be allocated to increasing atmospheric CO2 concentrations (Sombroek, 1991) (from 315 ppmv to 352 ppmv in the period 1959 to 1989 (White 1990) since wheat and rice for instance are C3 plants.
As noted above, current fossil carbon use is around 6 Gt annually. Biomass burning may use a further 1.8-4.7 Gt C currently (Crutzen & Andrae 1990). In Kalimantan alone a startling 3.6 x 106 ha were burned in the 1983-1984 El Nino related drought. For the purpose of this analysis the amount of C assumed to be released as the result of biomass burning will be taken as 4.0 Gt for 1990 with no further claim against land use emissions. Growth of atmospheric CO2 concentrations will be taken as 1% per annum for the purpose of calculation of the worst case condition, the mean growth of 0.4% will be used as the current projection. A possible biosphere-driven climate cycle is shown below.
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Note: Volcanic/geologic release of green-house gases are not figured in this diagram. The carbonate role in relation to either biogenic factors, plate-margin subduction or volcanic release of CO2 is likewise, not presented. Over long periods of geological time (108 years), an alternating tectonic greenhouse/icehouse mechanism involving increased sea-floor spreading rate and ridge volume resulting in elevated sea levels, increased CO2 and release to promote greenhouse conditions as opposed to decreased sea-floor spreading rate and ridge volume, reduced CO2 discharge, reduced sea-levels and increased oceanic productivity from nutrient input arising from the exposed lands has been postulated by Mackenzie and Agegain. No overt mechanism controlling sea-floor spreading was proposed other than to suggest that "over geological time, the earth's internal energy, the fundamental component driving global tectonic activity, may be progressively decreasing". A consequence of this idea would be that some controlled anthropogenic CO2 releases should be allowable in compensation in order to "maintain a balance".
A recent estimate for total release of carbon to the atmosphere between 1800 and 1980 (Post et. al. 1990) produces a figure of between 90-120 Gt due to changes in land use and between 150-190Gt due to burning fossil fuels to give a total of between 240-310 Gt The median estimate is thus 275 Gt or 1.52 Gt annually. For calculation purposes using the density of coal as 2.0, this would require exposure and weathering of a fossil carbon volume of approximately 27.5 km square by 1.0 cm deep to produce the same release on an annual basis as the result of ice movements or other kinds of weathering, a figure that is well within the realm of possibility given known deposits. A release of 5.9 Gt (1988 fossil fuel use) would necessitate a volume of 54.3 km square by 1.0 cm deep. Note: coal density may range from below 1.0-1.7 with 40%-98% carbon.
If this interpretation is realistic then, in order to effect control of carbon releases, attention should be focused on current biomass production (C3 based): reforestation, aforestation and promotion of peat-forming wetlands. The general pattern of events which we may expect as the result of excessive fossil-fuel use will be the same as those following glaciation and a consequent CO2 spike only more so, with the potential for the polar caps to be eliminated unless progressive CO2 releases can be modified or appropriate long-term carbon sinks constructed.
As previously indicated, the early to mid Carboniferous was probably a high CO2 regime with organic primary production very much higher than today. The mesozoic is estimated to have had similar periods with carbon dioxide concentration up to 11 times that of today (Arthur et al 1991), so much so as to permit the twin phenomena of primary and secondary consumers with large bodies (the dinosaurs) and extensive accumulations of organic carbon in what became immediately reducing environments. It may be noted that a massive ice-age developed in the Carboniferous-Permian transition. This might have been instigated by photosynthetic draw-down.
The mechanism which would ensure release of carbon gasses could also include outgassing from volcanic activity such as that observed in the Mid Cretaceous (Kerr 1991) and perhaps where carbon-rich sediments and deposits (carbonates) dominate platforms underlying volcanoes (Allard et. al. 1991) or are subducted at plate margins.
By this model, human induced industrial liberation of CO2 may be a concentrated version of the exposure of inorganic and organic carbon to oxidation which was previously controlled by natural events. At this point in time, instead of moving into a period of glaciation induced by photosynthetic draw-down, as perhaps indicated by the "little ice age" (1570-1650) which was associated with a drop in temperature of only 0.5 deg. C (Briffa et. al. 1991), the globe is now being subjected to additional CO2 injections from relatively deep carbon deposits.
How fast is carbon being sequestered and where ?: the terrestrial problem
When the question of coal and other fossil hydrocarbon formation is examined in detail it becomes apparent that we are somewhat short on practical data. The Carboniferous period was noted for the large carbon deposits laid down world-wide. Yet today we are able to locate few, if any, terrestrial situations in which extensive deposits of coal appear to be forming. The coastal or ombrogenous peat swamp forests of Indonesia have often been cited. The natural area of peat soils (>= 65% organic matter) in Sumatra is estimated to have been (7.3 - 9.7) x 106 hectares (Adriesse 1974) and may, perhaps exceptionally be up to 20 meters in depth, although some areas are quite shallow (1-20 cm) (Tjitrosano 1990). This might represent one quarter of all tropical peat lands (Driessen 1990). Substantial deposits are also found on the southern margins of Kalimantan (Stieffermann 1990) cited as 6.3 x 106 hectares (Kartawinata 1990) and in Irian Jaya 9 x 103 hectares (Kartawinata 1990). Much of the peat deposits in southern Kalimantan are however less than 1 meter in depth (KAPAS 1991). The area in Sarawak is 1.5 x 106 hectares and in the Malaysian peninsula 0.5 x 106 hectares. In Thailand, the former cover of peat swamp forest was 34 x 103 hectares now reduced to 8 x 103 hectares (Smitinand 1986). Ombrogenous peat in southern Kalimantan has been divided into two types (Stieffermann et. al. 1990) high peat (a fossil formation), located on the highest places between separation of river basins, and presently undergoing destruction at the rate of 12-14 cm/100 years and low or basin (Sarawak) peat undergoing active formation. The high peats appear to range in age from 2,500 years BP to 8,000 years BP with historical accumulation ranging from 0.24 cm/yr in the oldest layers to 0.14 cm/yr in the most recent formations in association with an ecological shift from mixed swamp forest to a low canopy type forest as evidenced by pollen records.
The results arising from ecological analysis of the lowland peat ecosystem in southeast Asia are as follows (Whitten et.al. 1987, Whitmore 1984, Anderson 1964). The system appears to be self-limiting and the best estimate is that the oldest examples have taken around 4,500 years to develop to the present state with a central-rear acid limited, low productivity area and around 5 or so peripheral zones in which productivity increases progressively to the outermost. Those with fewer distinct zones are presently thought to the younger than the completely developed systems. In the case of the well developed structures there is as yet no really clear idea as to how long it takes before the central-rear low productivity area (acid-rich) becomes well defined. In the extensive peat swamps of Sumatra, the surface is markedly convex and not subject to flooding (Whitmore 1984). The specific gravity of the peat matrix is very low (Demont et. al.1991) (bulk density 0.07-0.18, median 0.125, n=71 (Driessen and Rochimah 1976)) and the systems are associated with coastlines advancing by deposition rather than being flooded and depend to some extent on rain-input for moisture in the upper levels of the mound during the rainy season.
The ecological situation is specialized and depends on the tropical marine interface with an initial frontal development (on the sea/estuary side) of mangroves. The mangroves cut down the silt and debris discharge by acting as a filter and thereby cause the water discharge system to "back-up". Without the mangroves occluding the drainage system in the first instance it is most unlikely that the coastal peat-swamp forest would ever develop. The other kind of peat swamp found in Indonesia is much more restricted in development associated with filled-in lakes and to some extent with a few occluded river valleys.
The coastal peat swamp assemblages do not show plant endemism (Muller in Whitten et. al. 1987) and so may be comparatively recent ecosystems and importantly the most productive associated forest proper arises as a peripheral nutrient dependent response. On a global scale, these systems appear to be limited. The mangrove dependency means they must at least be confined to the tropics, or close thereto. The high acidification and high phenolyic content means that the systems as a whole are actually not very productive. The available data on this is restricted but but the stem area/density measurements attest to this interpretation quite clearly (Stieffermann 1990) and management analysis (Tjitrosano 1990) classifies the systems as having low plant productivity with simplified associated food-webs. Also, such areas are among the last on the coasts of Southeast Asia to be developed and populated in contrast to nearby fertile areas such as Java (Knox and Mirabaya 1984). The peat accumulations appear in this case to result from a comparatively low production and high preservation ratio. One may ask if this was how most fossil carbon accumulations developed or if higher productivity regimes operated at some times in the past?
In Sumatra, recent peat deposits have been accumulating at an average rate of 0.3m/100 years although layers 10-12 meters below the surface showed higher rates (0.47m/100 years). More recently rates have dropped to 0.22m/100 years (top 5 meters). An even lower value for current accumulation rate 0.5 mm/yr) has been cited for the deep central dome areas (Driessen 1977). The vast majority of deposits are 1-8 meters or so. A recent survey in Indonesia covering Kalimantan and Sumatra suggested that the mean thickness of coastal peat in the areas considered was 3.0 m (Supardi and Diemont 1987). The same reference cites earlier estimates of 16.5 x 106 hectares for lowland peat in Indonesia with a depth in excess of 1.0 m. and 8 x 106 ha. of peat over 2.0 m. in depth. Current coring (1990-1991) suggests 6.0 m as a maximum depth (Brady 1992, personal communication).
In conclusion it appears that the coastal tropical peat swamps, at least in southeast Asia, are rather special ecosystems. Carbon certainly accumulates therein but there is little that can be used to suggest that they represent a dominant mechanism for coal formation since they do not really appear to be very stable nor do they support a very rich flora. It seems curious that there appear to be no endemic species, particularly in the depauparate acidified areas. The overall associations have been estimated by one worker (Muller in Whitten et. al. 1987) to have been around for 18 million years or so. Discharge of dissolved organic materials from the swamps into the sea may play some role in fossil carbon accumulation but the mechanism involved is unclear.
These factors make it possible to hypothesize that different circumstances might have been involved to account for past accumulations of coal in contrast to the conditions which are apparent today. Fossil records have shown that carbon sequestering systems of the past (e.g. coal-forming mires) lasted for extremely long periods of time involving several tens of millions of years during which little change was noted. However even these systems were susceptible to climate change, which may well have been self-induced due to the atmospheric drying induced by carbon dioxide draw-down and that change produced community structure collapse when relatively few (probably < 20% of species) were lost from well adapted systems (DiMichele et al 1987, DiMichele & Phillips, in Press).
There is a questions as to how much coal the swamp forests in southeast Asia would yield even if the coastal landform was sinking. As experience with the Indonesian transmigration program has shown (Knox and Mirabaya 1984), relatively mild disturbance soon leads to the entire elimination of the surface peat accumulations which are often somewhat shallow. Today the coastal peat swamps are rapidly being drained and converted to agricultural use (Tjitrosano 1990, Smitinand 1986) or logged with consequent failure in regeneration (Tjitrosano 1990). The estimated original 20.695 x 106 ha. of peat swamp throughout Indonesia has now been reduced to 16.975 x 106 ha., 1.67 x 106 ha. of which are included in existing reserves (Silvius 1989).
Tropical forests are estimated to store only 11% of the world's soil carbon pool (1380 GtC in 1838x106 ha) however, they store 20% of the world's terrestrial carbon (including vegetation and soil) and 46% of the world's living terrestrial carbon pool while accounting for about half the global forest area and exporting 0.2 Gt of carbon annually to the oceans. The world's terrestrial biota as a whole is currently estimated to store 835 Gt of carbon with the plant biomass being from 410-700, (median 555) (Sundquist 1985). For the purpose of calculation the value of 500 Gt C (Brown and Lugo 1982) will be used as the global measure of terrestrial plant organic carbon. Tropical forests exhibit the fastest turn-over rate (<34 years) of all the world's forest biomes. Temperate forests require 50 years to attain the same biomass as achieved by tropical forests in 25 years. The net terrestrial primary production is estimated at 50-60 Gt C/yr. The atmosphere currently contains 751 Gt C (353 ppmv CO2, and 1 Gt C = 0.47 ppmv CO2), compared to a pre-industrial content of around 550-590 Gt C, a difference of 165 Gt C or so. The oceans are estimated to contain an immense 36,600 Gt C (Sundquist 1985), the majority of which is in solution, particularly in the oceanic depths. Of the 30-80 Gt C/yr production, only 0.006-0.7 Gt of this carbon is buried on continental shelves with a further 0.002-0.2 Gt on the slopes and in the deeps. The reconstructed terrestrial standing stock of carbon might have been around 1080 Gt C (plant cover). An alternate figure (Adams et.al. 1990) for the natural or reconstructed standing stock of terrestrial carbon is given as 924 Gt For the sake of example, the figure of 1080 Gt will be used. Stocks of "recoverable" fossil carbon have been estimated as between 6,100-7,700 Gt (Adams et.al. 1990). See chart 2. This has also been estimated to be around 325 Gt C (Houghton and Skole, 1991).
The total area of coastal peat associations in southeast Asia (Malaysia and Indonesia) may now be up to 20 x 106 ha (Soepraptohardjo and Driessen 1986). If this is taken as 2 meters in depth (on average) with a bulk density of 0.1 gm/cc (a normal peat soil as defined in (Driessen 1990), for the purposes of calculation) and an assumed carbon/organic matter content of 0.5, the total carbon content would be 20.0 Gt , that is, scarcely 3 years of anthropogenic use at current rates. Deeper overall deposits make little difference to the calculated stored carbon, a 3 m average depth means 30 Gt C overall and so forth. If accumulation is taken as 20 cm/100 years (given as 22cm/100 years in (Whitten et. al. 1987)) for the purpose of calculation, the annual addition of organic carbon would be 0.02 Gt assuming all peatlands are actively growing (1.0 t/C/ha/yr). The figure would be only 25% of this value if the lower estimate for accumulation in top layers of the central dome is used (0.5/2.0). However, a case has already been made to suggest that such a reduction is the consequence of a natural process of self limitation for mature formations and would not be characteristic of younger systems. Global tropical peats (32 x 106 ha.(Driessen 1977)) might fix 0.032 Gt C annually and all peats (420 x 106 ha. (Schlisinger 1990)) might account for 0.42 Gt /C/yr under the same assumptions (2mm/yr growth). It is estimated (Wiggers n.d.) that 0.05 Gt of C are annually shifted to the atmosphere from tropical peatlands due to development activities. The net release of carbon to the atmosphere in Southeast Asia was estimated (Palm et.al. 1986) for 1980 as between 0.15 - 0.43 Gt due to deforestation and land disturbance. These simple calculations show very clearly that carbon sequestering pathways, even for ecosystems that might overall be thought of as productive, are extremely restricted in cross-section compared with current rates of anthropogenic flux. Although they may have been relatively more significant in the geological past in providing a response to increased levels of CO2, such pathways have in recent times been sharply reduced in cross-section. Global peat formations are estimated by Garrels et al (1973) as 0.07 Gt/C annually.
Since CO2 concentrations already exceed the maximum observed in the ice-core record (300 ppmv) the likelihood of qualitative and quantitative "surprises" must be clearly anticipated at projected levels of 600-700 ppmv (approximately twice pre-industrial levels). We may speculate that certain geological and environmental processes may run faster than they have in the past. Such concentrations have certainly not been seen in the past 150,000 years. We may now be operating a form of "time machine" whereby processes that might formerly have taken tens of thousands of years to take effect will now proceed in tens or hundreds of years.
Environmentally sound and sustainable development (ESSD)
The question concerning an operational definition of sustainability has been raised on several occasions prompting repeated declarations to the effect that the wording provided by "The World Commission on Environment and Development" (WCED), "Our Common Future", is appropriate.
As part of the concept of "environmentally sound and sustainable development" (ESSD) the WCED (1987) defines "sustainable development" as "development that meets the needs of the present without compromising the ability of future generations to meet their own needs". By itself, the latter statement is unbounded and involves an appeal to "inter-generational equity" with the consequent implicit assumption that the future will somehow be able to take care of itself through increasingly effective and efficient technological adjustments regardless of the quality of available resource base.
The concept of ESSD can thus be re-worded as "environmentally sound development that meets the needs of the present without compromising the ability of future generations to meet their own needs". The phrase "environmentally sound" has intuitive appeal but it does not specify immediately operational or measurable criteria for use as the basis for a quantifiable definition.
Currently, the world population distribution between developed and developing countries is 24:76. In the case of energy (electricity) for instance, "needs" specified as "per capita resource use" already span a range, of 40:1 for "most developed" to "developing" countries. For liquid hydrocarbons this is 60:1, for gasoline alone 390:1, for all solid fuels (including wood) 14:1. Consumption of copper by the U.S.A. is higher than that of India, on a per capita basis by 245:1 and so forth (Parikh et. al. 1991). In developed countries there is currently no reason to suppose that per-capita resource-use "needs" are leveling off. Likewise, there is no reason to suppose that the per-capita resource-use aspirations of the developing countries will be any less. For the sake of global stability, if for no other reason, enviromentally appropriate energy supplies must be found to accommodate the expectations of the developing world.
The ESCAP/UNDP Workshop on implementation of the regional strategy on environmentally sound and sustainable development, 1-5 July 1991, Rayong, Thailand therefore insisted that the concept of "sustainable development" should be more carefully examined in order to provide an operational link between "environmentally sound and sustainable development" (ESSD) and (the) variables used for monitoring, based on strongly stated environmental objectives ... "to quantitatively evaluate movement towards or away from the goal of ESSD". The workshop also called for the development and strengthening of ESSD performance criteria and indicators.
In a gross sense, the question of specifying "environmentally sound" involves definition of the the extent to which the global ecosystems, which are themselves "counter entropy", can accommodate the effects of increased entropy without terminal break-down. The discredited phrase "absorptive capacity of the environment" is thus identical to the idea of "environmentally sound development". The item which is missing from most attempts to develop a definition combining "environmentally sound" with "sustainability" relates to the concept of "balance" between the undesirable effects of development and the continuing requirements for the expression of a competent biosphere.
Smith (1991) notes that although WCED gave a meaning to "sustainability" the word is now defined and re-defined by its users depending on their interest. Thus the co-ordinator of Asia-Pacific Peoples Environment network observes: "the term 'sustainable' from the ecological point of view means the maintenance of the integrity of the ecology. It means a harmonious relation between humanity and nature, this is harmony in the interaction between individual human beings and natural resources". "The term 'sustainable' from the point of view of non-ecological elites means 'how to continue to sustain the supply of raw materials when existing sources of raw materials run out'"(Mohammed 1990).
UNEP declares that "Environmentally sound and sustainable development is not business as usual. Current models of economic development have swelled superficial increases in standards of living, based on material possessions, at the expense of health and our future. Sustainable development means change and sacrifice for long-term gain. The alternative is massive and irreversible ecological destruction" (Tolba, UNEP no date cited by Smith 1991).
An exact recipe to enable the achievement of ESSD however, is beyond definition at present. The concept of "carrying capacity" or "population support capability" (FAO 1984) might be used to help with the definition. The FAO (loc. cit.) approach furthermore takes no account of opposing uses that would reduce potential agricultural productivity. Although such a "capability" is easily defined in a simple environment in terms of a constant sustainable population density for a given resource regime, it is much more difficult to specify where primary environmental factors are subject to variation thereby inducing population fluctuations and where potentially unbounded energy injections are involved. Thus India maintains a relatively high population density at a low per capita energy use while Japan operates at a much higher ratio. One potentially limiting factor is fossil fuel use and energy use in general. There is an urgent requirement to define environmental indicators that can be used to quantitatively measure progress towards or away from the elusive goal of ESSD. As an absolute minimum such definitions will have to accommodate towards reversing global warming and to curtail high-atmosphere ozone loss.
One of the most difficult areas to deal with will be the assessment of the effects of energy injections. On the one hand energy enrichment to human social systems is clearly used to promote increases in carrying capacity and the elaboration of counter-entropy structures. On the other, the act of energy capture and subsequent energy-degradation promotes vast and as yet unquantified negative environmental impacts and instabilities. Urgent research is required to assess the possible effects of increasing energy fluxes on global, regional and local systems.
The recent Gulf conflict was predictable in terms of existing energy pricing policies, energy flows, and the transfer of military goods elaborated with under-priced energy as was the consequent resultant carbon-cost. This consisted of: 1) destruction by burning of oil, 2.6% of global use (Bakan et.al. 1991 prior to the end of 1990; 2) fossil carbon used in prosecution of hostilities; 3) fossil carbon equivalent of destroyed and worn military equipment; 4) carbon equivalent of degraded explosives; 5) fossil carbon equivalent of demolished infrastructure, etc.).
Global energy fluxes.
The question of energy throughput and its effects on the structure and function of human and natural ecosystems is of considerable interest from the ecological perspective. It appears that natural systems have evolved in association with relatively consistent energy fluxes even if these may have varied somewhat over the long-term of the earth's history. The relationship between the higher species diversity of tropical systems (high natural energy flux) compared to that of polar regions (low natural energy flux) together with the intervening trends are well known. It is also well-known that most species are not abundant through their range. A possible explanation for this is that the majority are relics of past environments in which different global conditions and climates pertained. Global species diversity may thus be properly viewed as a form of ecosystem memory which will permit a competent biological response to a host of differing environments including those predicted to develop as the result of anthropogenic climate change.
Examination of the laws of thermodynamics leads to the conclusion that energy transformations involve what may be termed an entropy cost in that energy is available as a once-only use-function in transformation from a higher to a lower state insofar as the ability to perform work is concerned. Such socially competent energy transformations as result in the elaboration of useful work also provide an increase to the general economy and at the same time an entropy penalty cost. The difference in these two conditions is intended to result in a socially useful state of increased order.
Natural ecosystems have resulted from an order-positive imbalance on the solar energy degradation pathway. In other words, an anomaly has been created in the action of the second law of thermodynamics, although entropy increases nature never-the-less converts essentially un-ordered chemicals into more ordered physical states, as long as energy flow is maintained, ie. an order-positive imbalance exists based on solar energy throughput.
At the other extreme of energy throughput, as associated with the detonation of a thermonuclear device on a city or the more moderate expression of modern conventional warfare, an order-negative imbalance results from the energy degradation.
Thus we may well ask at what multiple of solar energy throughput per unit area and time might we expect to find an acceptable ratio between the entropy cost penalty and maintenance of physical system order compatible with overall ecosystem well-being ? An answer to this question might also tell us at what level of energy throughput per unit area we might expect to see a point at which subtraction from established cultural and technical (physical) order is initiated. We may then approach the analysis of human ecosystems from an ecological perspective. The concept of an order-positive imbalance, or, a unit increase in order, for a given energy flux must take into account the entropy cost of energy conversion/capture, transmission and degradation. All energy capture schemes involve environmental costs. Hydro projects may alienate biodiversity (Harger and Culhane 1974), solar energy panels may block sunlight from reaching the ground and thus potentially reduce biological productivity. The selenium and metals etc. used in photoelectric cells and peripheral structures must be mined and processed involving energy costs and appropriate carbon penalties as well as the induction of direct environmental damage and pollution etc. See chart 3.
By taking these factors into account, one may then inquire into the relationship in human systems between unit increase in order and energy throughput. This may be done in gross terms per unit time per unit area (local, regional global) and may also be properly stratified by grade of energy input. Since we may also properly regard money as a social claim on energy and thereby indirectly as a means of accounting for socially available energy (considering all forms from fusion energy, hydro-electrical energy to low-grade heat energy etc.), questions may be elaborated and answered on an ecological basis concerning the relationships between capital accumulation, expenditures or investments per unit area and the resulting energy/order relationships. For instance fossil fuel (oil) is extracted from the middle east, exchanged at a low value-rate for hard currency (firm claim on energy), used by industrial nations to elaborate infrastructure, industrial capacity and, incidentally, military hardware which is then swapped back for the original capital creating an immediate primary imbalance which eventually leads to destruction of both the military equipment and the developing country infrastructure along with significant environmental degradation, and as yet an unquantified contribution to global warming.
By recourse to such reasoning we might be able to predict size limitations for cities and other human ecological assemblages with different structural and energy-use characteristics in the same way that such considerations have governed the size character and complexity of living systems as single entities and as complex interactive ecological associations. To do this we must elaborate and implement a set of mathematical tools or indicators. To help map future progress we must furthermore immediately embark on a detailed environmental cost-accounting exercises to assess the relative merits of all energy capture schemes (nuclear, solar, wind, hydro, fossil fuels, tidal etc. etc.). Only the full development of such a universal accounting scheme will allow for appropriate selection amongst alternate energy capture scenarios and for an objective identification of the correct mix to be used at local, regional and global levels consonant with environmental principals and the necessity to promote development across the globe in a sound and sustainable manner. Implementation of the resulting technical capacity can be undertaken through re-direction of armaments finance.
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