United Nations Conference on Trade and Development (UNCTAD) concluded a few years ago that natural rubber stands to gain from internalization of environmental costs in the entire rubber industry.  The economic variables prevailing in the natural rubber market favour internalization:  the supply elasticity is below unity, and the price elasticity for demand is estimated to be significantly less than one.  

Furthermore, the 90- 93% international market share of Asian NR producers is coupled with intermediate export dependence as rubber accounts for only 3.5 % of their total exports.  Unilateral attempts to pass on environmental cost increases appear feasible, although concerted action among the main producers is desirable and cooperation with producers and manufacturers of synthetic rubber is necessary.

The elastomer market is dominated by renewable natural rubber and non-renewable fossil-fuel-derived synthetic rubber:  in some applications they are substitutes and in others, complements.  Tyre production accounts for over 50% of elastomer consumption and 60% of natural rubber consumption.  The current share of natural rubber in total tyre production is unlikely to change much.  Rubber cannot realistically be replaced in tyre production, nor can tyres themselves be replaced by a different product.  Many general rubber products also appear very difficult to displace or replace.

Initial stage of UNCTAD’s programme on internalization prospects in the rubber economy emphasized identification and measurement of malign and benign environmental effects in the production, manufacturing, and consumption of synthetic vs. natural rubber to demarcate and appraise environmental costs and benefits.

Activity and environment
One key factor in the relationship between any activity and the environment is that it is impossible to consider any individual activity without reference to the overall consequences; nevertheless, it is useful to introduce a taxonomy.  In the case of the rubber industry, it is helpful to break down the activities which impinge upon the environment into those associated with (1) the production of the raw material, (2) the transformation of the raw material into finished products, (3) the use of such products in service, and (4) the final recycling or disposal of the products.  Many studies relating to the last-named, such as investigations of the scrap tyre problem, fail to recognize the importance of the other elements which may either amplify or mitigate the problem.  It is inevitable that we tend to base our analysis upon natural rubber, frequently in comparison with synthetic rubber, but many of the factors (such as factory emissions, product service and ultimate disposal) apply to all elastomers.

Renewable vs. non-renewable
In most discussions on the environment, resources are divided into renewable and non-renewable categories.  The former includes most natural products.  The latter includes most mineral resources, although many of these are recyclable, and fossil fuels.  Some countries tend to consider their large hydroelectric capacity as a green resource.  Fossil fuels are not only non-renewable, but their combustion contributes to increases in global carbon dioxide levels and a possible greenhouse effect which may lead to higher ocean levels and the loss of global land mass.

The present pattern of consumption of natural and synthetic rubber remains a relatively constant 40% and 60% respectively, of the total elastomer consumption. The main advantage of SR is that it can be mass-produced to meet a wide range of specifications, although in reality more than 80% of SR products could be produced using NR. Certain industrial products, however, require the unique properties of NR with the largest single market being the tyre industry, which accounts for ca. 70% of world NR consumption.

NR is the strongest of all rubbers and has excellent dynamic properties (e.g. resistance) which accounts for the fact that aircraft tyres comprise 100% NR. In other aspects such as tolerance to environmental damage (e.g. by ozone and oils) NR competes less favourably with SR.
 In addition to its unique dynamic properties, NR has the advantage that it is a renewable, non-polluting source of elastomer as opposed to SR, which is manufactured from crude oil. Furthermore, in a world where increasing consideration is given to the environmental costs of production, NR compares much more favourably with SR.

For example, production of 1 t of NR requires 15 to 16 Gj of energy compared to 108 to 174 Gj for SR, depending on the grade of SR produced. In addition to the high energy costs, SR production is also a source of pollution whereas NR cultivation has few detrimental effects on the environment. It is the processing rather than cultivation of NR that has the potential to pollute, although this can be minimised through effective process management.



Environmental benefits Carbon business
There has been increasing national and international concern over the accumulation of Green House Gasses (GHG) particularly CO2 and its effect on global warming. CDM of UNFCCC provides opportunity to seek remunerations for the environmental services provided by NR plantations.
 Studies done in Sri Lanka indicate that, a rubber tree can fix about one MT of CO2 carbon during its 30-year cycle. A hectare of rubber will therefore provide about 300 MT of CO2 for trade. The total land extent of rubber in Sri Lanka is forecast to increase to 140,000 ha by year 2021 and to 153,000 ha from the present extent of 127,000 ha. Therefore, by year 2021 the total CO2 available for trade in Sri Lanka would be about 42,000,000 MT and by 2031, would be about 45, 900,000 MT of CO2, if all rubber plantations are made eligible to receive credits for the environmental services provided by the rubber industry of Sri Lanka.

Also, rubber trees add about 23 MT/ha of CO2 to the soil through annual leaf fall, but part of which decomposes and re-cycled to the atmosphere. About 23 Mt of carbon(84 MTof CO2) are removed from the tree as latex yield in 30 years, most of which are used in value addition and therefore retained and not lost. Unlike hydropower or similar projects for emission reduction, planting trees for CO2 sequestration is subject to environmental changes and hence exhibit some uncertainty. The present market rate for a MT of CO2 varies from US$ 5 to 20.

Additional carbon trading benefits from rubber include; a) Rubber wood as a source of renewable energy, replacing fossil fuel, provides equivalent CO2 for trading,b) In power generation, 3kg of biomass is required to compensate one kg of fossil fuel. Therefore, the biomass of a hectare of rubber at the end of 30 years would replace 64 MT of fossil fuel, c) The emission reduction potential by biogas generated from rubber factory effluent is around 12,000 MT per year, and d) Power factor correction and factory modernization for electricity saving in rubber processing industries also qualifies for carbon trading by emission reduction

Soil conservation
Trees such as rubber play an important role in conservation of soil and water resources, they not only provide a long-term canopy, which protects the soil from erosion by wind and rain, but they also root over a greater area, depth and duration than short-term crops and so help bind and protect the soil. Litterfall from trees adds organic matter to the soil, which improves the surface soil properties so that rainfall infiltration is increased and surface run-off is reduced.

In Sri Lanka, rubber tends to be cultivated on land where few crops, other than tea, can be grown commercially and in the major rubber growing areas as much as 50% of the rubber lands have slopes of between 45 to 60%. Although tea is also grown on steep land, it fails to offer the same degree of protection to the soil as rubber, with an average soil loss of 35 MT ha-1 yr-1 compared to just 10 MT ha-1 yr-1 for rubber.
In terms of soil conservation, the properties of rubber plantations have been likened to that of native forests.  Forests can recycle about 8.33 t of dry litter per year as compared to 3.7 to 7.7 t yr-1 in rubber plantations; it is only in the older rubber lands where nutrient recycling via litter approaches that of native forest ecosystems.

Agronomic efficiency
NR does not impoverish the land upon which it is grown. Fertiliser inputs are very low and the surrounding soil appears to be enriched by the abundant leaf fall. Furthermore, biodiversity remains remarkably high in rubber plantations in marked contrast to most forms of monoculture. Excellent agronomic techniques assist in the conservation of the environment within rubber plantations. Measures include terracing, slit pitting, bunding and mulching and the growth of leguminous cover plants between the rows to assist with nitrogen fixation. Biomass burning is now discouraged during replanting. Moreover, it is possible to grow a wide variety of crops during the tree’s immature period, further enhancing its environmental credentials.

Forest conservation
The rapid loss of forest cover in Sri Lanka had been a major cause of concern in terms of the environmental impact. The forested area in Sri Lanka has declined from 70% in 1900 to less than 23% in early 2000, which translates into an annual rate of deforestation of more than 40,000 ha yr-1. This compares with a replanting rate of only 2000 ha yr-1. Parallel with the decline in forested area has been the rapid increase in population, rising from 11.5 to 18.5 million over the same time period.

 Conclusion
We have been talking about the eco-friendly credentials and carbon sequestration potential of natural rubber plantations, mostly in our own forums, for several years now. But little has been done until now to market the green image of natural rubber for tangible financial gains. Sri Lanka is yet to initiate action.
(The writer can be contacted at [email protected])