November 3, 2009

Global Warming and carbon cycle


In the Amazon alone, scientists estimate that the trees contain more carbon than 10 years worth of human-produced greenhouse gases. When people clear the forests, usually with fire, carbon stored in the wood returns to the atmosphere, enhancing the greenhouse effect and global warming. Once the forest is cleared for crop or grazing land, the soils can become a large source of carbon emissions, depending on how farmers and ranchers manage the land. In places such as Indonesia, the soils of swampy lowland forests are rich in partially decayed organic matter, known as peat. During extended droughts, such as during El NiƱo events, the forests and the peat become flammable, especially if they have been degraded by logging or accidental fire. When they burn, they release huge volumes of carbon dioxide and other greenhouse gases.

It is not certain whether intact tropical forests are a net source or sink of carbon. Certainly, the trunks of trees are a large, stable pool of carbon that grows as forests mature or regenerate on previously cleared land. But trees, plants, and microorganisms in the soil also respire, releasing carbon dioxide as they break down carbohydrates for energy. In the Amazon, huge volumes of carbon dioxide escape from decaying leaves and other organic matter in rivers and streams that flood large areas of forest during the rainy season. Undisturbed tropical forests may be nearly neutral with respect to carbon, but deforestation and degradation are currently a source of carbon to the atmosphere and have the potential to turn the tropics into an even greater source in coming decades.

That's way we should keep the forest because it will help to stabilize the earth climate. Deforestation will impacts many factor in environment. see alsoImpact of deforestation in tropical forest biodiversity

No comments: