Forests and the atmosphere

The greenhouse effect is a natural phenomenon whereby gases in the atmosphere trap heat which would otherwise be radiated into space. Without this greenhouse effect, the average temperature of the earth would be about 30 C lower than it is.

However, the proportion of greenhouse gases in the earth's atmosphere, especially carbon dioxide (CO2), is increasing as a result of human activities. Emission of fossil fuels combustion accounts for about 65 percent of the additional carbon dioxide (CO2) currently found in the atmosphere, while the other 35 percent is derived from deforestation and the conversion of natural ecosystems into agricultural systems.

Forests play an important role in the global carbon cycle and help to protect the atmosphere and mitigate climate change. Young forests act as a major carbon sink because carbon dioxide (CO2) is taken up from the atmosphere and used to produce the carbohydrates, fats, and proteins that make the trees grow. Carbon uptake is greatest in the early years when the rate of growth of the tree is at its maximum, later the forest acts as a carbon reservoir.

If greenhouse gases continue to increase at the same rate as in recent decades, global warming could have catastrophic consequences such as drought, disease, floods, loss of ecosystems and species and rising sea levels.

In the forestry domain only, researchers consider that global warming will have severe and rapid changes on forest production and species composition over large areas, hence making forests in many regions no longer sustainable. Such changes would have major impacts on biodiversity, timber supply, commercial forestry, recreation, as well as water supply and erosion rates.

But it is precisely forests which can contribute to mitigate these effects through environmental planning and sustainable forest management practices that reduce sources of greenhouse gases and by maintaining and expanding sinks of greenhouse gases.

Among those practices are: sustainable harvesting methods to replace destructive logging; conservation of standing primary and old-growth forests and stocks of biomass; reduction of slash and burn practices; substituting extractive reserves and producing timber and non-timber products sustainably through integrated resource management and development schemes, increasing harvest efficiency in forests, by harvesting more species with methods that damage fewer standing trees and utilizing a higher percentage of total biomass. Expanding fuel wood plantations to provide energy and reduce pressure on natural forests.

Moreover, legal instruments have been developed since the Earth Summit Conference was held in Rio de Janeiro in 1992. This conference lead countries to acknowledge the need to adopt a series of measures to reduce global greenhouse gas emission. This commitment became legally binding by the adoption of theKyoto Protocolto the United Nations Framework Convention on Climate Change in December 1997. In this agreement, industrialized countries and countries with economies in transition (Annex I countries) agreed to binding commitments to reduce their emissions of greenhouse gases by 2008-2012, with an average of 5.2 percent below 1990 levels. The Kyoto Protocol came fully into force last February 16, 2005

last updated:  Monday, February 28, 2005