Issue 52 / October - December 2005
Global Warming and Forests
Is the number and severity of floods, droughts that cause famine and deaths, forest fires, hur ricanes and ice melts increasing? If there is such an increase, what is the main reason for it? Unfortunately, in accordance with rapid industrial growth after the Industrial Revolution, there has been a remarkable increase in the accumulation of carbon dioxide and other greenhouse gases, as well as in the average temperature of the Earth. According to the most recent global evaluations, these temperature increases range from about 0.4 to 0.8Ă‚Â° C in the last 150 years. After the 80s, this warming became more evident and in almost every year of this period there were high temperature records. In terms of global average temperatures, 1998 was the warmest year since 1860, the beginning of the recording of temperatures with instruments. It is estimated that the average temperature of the Earth will have increased by about between 1 and 3.5Ă‚Â° C in comparison with 1990, and that the changes which have been observed in the climate because of this increase will continue. What will happen if global warming carries on like this? We estimate that sea levels will rise due to the melting of snow and ice caps, that climate zones will shift, violent rains and floods will occur more frequently, many places will be subjected to desiccations and droughts, while epidemics and agricultural pests will increase.
Greenhouse Gases and the Greenhouse Effect
A greenhouse is a place that is usually covered with glass or plastic walls where early season vegetables and house-plants are cultivated. Rays from the Sun can easily penetrate a greenhouse, but once they hit the ground they are transformed into thermo-energy, with the wavelength of the beams shortening and their energy diminishing. As a result, these beams with a shorter wavelength cannot leave the greenhouse due to the glass or plastic walls. Therefore the warming of the greenhouse increases as more and more rays enter. We call this process the greenhouse effect.
Similarly, some gases in the strata of the atmosphere are called greenhouse gases since these gases cause the same greenhouse effect for the Earth. These gases include carbon dioxide, methane, nitrogen oxide, ozone, chlorofluorocarbon, and water vapor. These gases have been created with a property that does not prevent (or prevents to a very small extent) the light energy that comes from the Sun from reaching the Earth and that prevents the infrared heat energy waves that are formed after this energy reaches the Earth from radiating to the higher layers of the atmosphere. Both the Earth and the layers of the atmosphere close to the Earth are heated by these gases. If there were not any of these gases surrounding the Earth it is estimated that the Earth would be 33Ă‚Â° C colder. Although there is a delicate balance and measure among the gases in the atmosphere that allows the maintenance of the Earthâ€™s temperature at a sensible level, human beings are carrying out practices that can ruin this balance. We, as human beings, are responsible for the global warming that is perceived as a danger today.
Carbon dioxide is half the reason for the total greenhouse effect. This gas is formed as a result of the use of fossil fuels, the respiration of humans, animals, and plants, and the disintegration of organic substances. Industrial development has caused a rapid increase in carbon dioxide in the atmosphere. It is known that 85% of the carbon dioxide emitted into the atmosphere comes from fossil fuels, with 15-20% stemming from the respiration of living beings and the other ecological continuous cycles.
In the last 150 years, a total of 389 Gt of carbon dioxide has been emitted into the atmosphere. 265 Gt of this carbon dioxide comes from the consumption of fossil fuels and the production of cement. 124 Gt comes from changes in land use. 214 Gt of this total has been reabsorbed by land and sea ecosystems and the oceans. This means that there is a surplus of 175 Gt of carbon dioxide in the atmosphere.
The Importance of the Forests
Forests play an essential role in lowering the diffusions of greenhouse gases that are emitted into the atmosphere and in forming â€ścarbon absorptionâ€ť by occluding greenhouse gases in the atmosphere. Thus, except for sedimentary rocks, 67% of the carbon kept on the land is stored in the forest ecosystem. 75% of the carbon kept by vegetation is stored in the forests. In addition, as long as some long-lived wooden products (wooden houses, furniture, etc.) decay or are burnt they remain as carbon storages.
As we all know, during photosynthesis the carbon dioxide that is taken from the atmosphere is separated into carbon and oxygen molecules. Then the carbon is stored in the roots, trunks, branches, and leaves of plants, being used in order to form carbon hydrates. Therefore carbon dioxide, the most essential greenhouse gas, becomes balanced. We can compare this to a huge factory that works very quietly and causes no waste. It is such an efficient factory that it transforms harmful substances into useful ones. We cannot say that we human beings appreciate this factory or protect its resources. Although today forests cover 3.7 billion hectares, comprising 30% of all land, between the years 1990â€“2000 on average 9.4 million hectares of forest were annually removed. That means that during this period the forest regions of the world diminished by 2%. As a result of such negative occurrences, because the carbon balance of vegetation, soil and organic substances had been destroyed, the forests, one of the means of Godâ€™s mercy upon us, have become sources of carbon dioxide and a tragedy due to our exploitation.
Ligneous living masses increase each year, while falling leaves add to the carbon storage. As a result, forest ecosystems contain carbon. After the growth of trees, most of the carbon dioxide they occlude each year goes toward developing the biomass of the tree. This means that in the first 30-40 years a high rate of carbon storage occurs. As the forest ecosystem develops, the organic substance of the soil and the total respiration in the ecosystem (occlusion of carbon dioxide) increase. When the ecosystem has fully developed, it no longer has the characteristics of â€ścarbon absorptionâ€ť anymore. In this case, the amount of carbon taken from the atmosphere is equal to the carbon emitted back by the biomasses of the trees and is kept in the soil. The time it takes for a tree to fully develop depends on the type of tree and the climate zones. However most of the carbon storage occurs in the first 60-100 years. It has been determined by research that a well-developed 100 year-old beech tree absorbs 40,000,000 m_ of air with its leaves for photosynthesis and binds 1,200 m_ of carbon dioxide in the air as 6 tons of carbon.
As well as being a community of trees, forests are environmental systems and living communities, with soil that was created over a thousand years, with millions of plants, animals, and microorganisms, and their reciprocal relationships. It is very difficult for this system to be restored once destroyed by human beings. Forests provide an essential service in a consistent and balanced carbon flow between the biosphere and the atmosphere with respiration that is dependent on photosynthesis and the activities of life in the soil and the plants. Forests are the lungs of the Earth.
In the light of these facts, the duty of human beings is to protect the vegetation and to reforest the treeless lands, to decrease human pressure on existing forests and to improve forests that have been damaged. Oxygen, nitrogen, water vapor, and carbon dioxide were created as continuous cycles for the continuation of the life. When these treasures have been damaged as a result of the greed of human beings, the costs are too high for us to reverse the trend. Billions of people are victimized; yet they are nor directly responsible for such acts. These delicate balances can be revived if we lead a simple and modest life, where we consume less and we produce less. Those who ought to understand this first must promise to be more respectful to God and to change themselves. Even if we fulfill our responsibilities, we can do nothing today but hope that those whose destructive powers are great may desire such a spiritual revolution.
Cepel, N., Ekolojik Sorunlar ve Cozumleri, Tubitak Populer Bilim Kitaplarâ€ş, Ankara: 2003.
Roulet, N.T., Freedman, B., What Trees Can Do to Reduce Atmosferic CO2, Tree Canada Foundation, Ontario: 2003.
Report by the Commission of Climate Change Experts, DPT (Turkeyâ€™s Official Planning Organization), Ankara: 2001.
Food and Agriculture Organization of the United Nations, 2001, Global Forest Resources Assesment 2000, ISSN 0258-6150, FAO Forestry Paper:140.