Greenhouse problem begs solution
By Susilo
JAKARTA (JP): The greenhouse problem has become an important international issue in the last two decades and begs a solution.
The deleterious warming of the atmosphere is caused by the accumulation of greenhouse gases, namely: carbon dioxide (CO2), chloroflourocarbons (CFCs), methane (CH4) and nitrousoxide (NOx).
Given that the biggest component of those gases is CO2, the solution should focus on this gas, especially in relationship to the role tropical forests play as a CO2 sink.
CO2 is emitted from a wide variety of human activities, but mainly from the burning of fossil fuels and changes to land use through large-scale deforestation.
People depend on fossil fuels and wood for 88 percent of their energy demands. Other potential sources of energy, such as nuclear power and hydroelectric power account for only five and seven percent of the total energy demand, respectively. As this demand gradually increases every year, the amount of CO2 emitted also increases.
Large-scale deforestation, especially of tropical forests, is a major source of carbon dioxide. People exploit forest for timber production, agricultural land expansion and settlement. These activities will change the stored carbon and release CO2 into the atmosphere.
The ocean is potentially the largest CO2 sink. In the ocean CO2 is converted by marine micro-organisms into inorganic compounds such as carbonates or into organic compounds which are used in the food chain. Scientists estimate that the ocean has absorbed about 26 percent to 34 percent of the CO2 which has been released from burning of fossil fuels.
Young forests are another potential CO2 consumer. New forests absorb CO2 through photosynthesis and convert it into carbohydrates important for plant growth. It is estimated that one hectare of young forest is able to absorb about 6.2 tons of CO2 a year.
Balance
Ideally, there should be a balance between the emissions and the sinks of CO2 so there the gas cannot accumulate. However the continuing increase in energy consumption and the rate of forest clearing, the concentration of CO2 in the atmosphere is also increasing.
Carbon dioxide is formed from the oxidation of carbon. In mature forests, there is no carbon accumulation. There is an amount of carbon withdrawn from the atmosphere during photosynthesis, but approximately the same amount of carbon will be released during respiration. Therefore the role of mature forests is only to store carbon.
Each hectare of primary tropical forests stores about 90 tons of carbon. Tropical forests store about 60 percent of the total atmospheric carbon. Since this forest only occupies about 13 percent of land surface, the carbon content is very high. Consequently, any deforestation will release a large amount of carbon in the form of CO2. Deforestation in Brazil releases about 540 million tons of CO2 which is equal to the amount of CO2 emission from the burning of fossil fuels in U.S., the highest energy consumer.
Clearing forests for fuel will release carbon immediately, while harvesting forest for wood products, will release carbon slowly through the decaying processes. In addition to this, deforestation will also affect the carbon content of the soil.
Due to the high carbon content of tropical forests, there is a high level of concern in developed countries to save these forests to store carbon. The cancellation of Scott Paper Corporation's Project to exploit 850,000 hectares of forest in Irian Jaya in 1990 due to pressure from NGOs; Prince Charles' call for a boycott of tropical timber in February 1990; and the ban by the Australian Federal Government on the import of rain- forest timber in February 1989, are only part of a series of boycotts and anti tropical wood campaigns.
Constraints
Yet, tropical deforestation goes on. Forest destruction occurs in developing and developed countries. The death of forests in Germany from air pollution and the unsustainable forestry practices in Finland are evidence of this destruction.
Withdrawing carbon from the atmosphere through reforestation is one solution to the greenhouse problem. Similar to the forest protection method, reforestation has some constraints, like land requirement and cost.
It has been estimated that to absorb the CO2 emitted from a single 500-MegaWatt coal power plant, about 1,000 square miles of forest is needed. To absorb the annual net flux of CO2, at least 465 million hectares of land and $375 billion is needed. Where this forest will be planted and who will pay are the questions that must be answered.
Another way to deal with the greenhouse problem is through the reduction of carbon-based fuel consumption. Carbon dioxide emissions in developed countries mainly comes from fossil fuel combustion, while in developing countries the emission comes from changing land use. In other words, high CO2 emissions in developed countries is a result of maintaining lifestyles, while in developing countries it is a result of fulfilling basic needs.
Sad to say, developed countries do not want to reduce their fossil fuels consumption. U.S. is the highest energy consumer and accounts for more than 21 percent of CO2 emission from the energy sector. After the success in the Gulf War and securing a cheap and reliable energy source, American energy policy gives low priority to more efficient energy uses let alone to the reduction of energy consumption.
There is no doubt that vegetation has an important role in solving the greenhouse problem, even though there are many constraints. Other solutions such as the reduction of carbon- based energy consumption and more efficient energy uses should also be considered.
Simultaneous action to reduce energy consumption in developed countries and maintain tropical forests are essential to solve this problem. Since it is a global problem, only good cooperation between countries will solve it.
Susilo is an environmental observer, a graduate of the University of Melbourne, Australia.