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Life on Earth Background Information
1. Rainforests cover 2% of the Earth's surface, or 6% of its landmass, yet they house over half the plant and animal species on Earth. They originally covered at least twice that area - and if deforestation continues at current rates, scientists estimate nearly all tropical rainforest ecosystems will be destroyed by the year 2030. 2. The world's rainforests are being destroyed at a rate of 2.4 acres (1 hectare) per second - an area equivalent to a football field. This amounts to an area the size of New York City every day, 78 million acres per year. In Brazil alone, home to one third of the Earth's rainforest, 50,000 square km is lost every year. In central and South America 2 - 4% of forest is destroyed annually. The remainder is in Africa: annual deforestation rates of between 8 and 15%, and South East Asia, where forest is destroyed at a rate of up to 8% per year. 3. The main causes of rainforest destruction globally are; - Land clearance for mining, oil extraction and hydroelectric dams.
- Slash and burn clearance for subsistence farming; the cleared area is then cropped for two or three years before it is abandoned.
- Clearance for firewood - one third of the world's population relies on firewood for heating and cooking. 86% of all wood consumed annually in the least developed countries is for fuel.
- Organised national/international logging operations.
- Extensive clearing for grazing - a cheap source of land (particularly in Latin America) to raise cattle for hamburger manufacturers.
- Government policies of resettlement - to remove pressure of overcrowding in the cities and make economic use of the land.
4. Between 40 - 50% of all life forms on our planet - as many as 30 million species of plants, animals and insects - live in tropical rain forests. Scientists estimate that an average of 137 species of life forms are driven into extinction each day. 6-9 million indigenous people inhabited the Brazilian rainforest in 1500. In 1992 less than 200,000 remained. 5. Many of the foods we eat today originated in the rainforests: including avocados, bananas, coconuts, black pepper, cocoa, lemons, oranges, cinnamon, cloves, rice, sugar, tomatoes, brazil nuts, cola, coffee and many more. The wild strains still in the rainforest of many of these plants provide genetic materials essential to fortify our existing agricultural stocks. A further 75,000 wild plant species have not yet been exploited by humans, many of them in the rainforest.
6. One quarter of all medicines owe their existence to plants. 70% of the drugs useful in cancer treatment are sourced only in the rainforest. Also medicines for heart ailments, hypertension, arthritis and birth control. 7. The greenhouse effect is caused by the millions of tons of CO2 our cars and factories discharge into the atmosphere. Tropical rainforests act as carbon traps, and as they are destroyed this effect is reduced. Moreover if they are burned more carbon is released into the atmosphere. 8. The projected economic value of 1 hectare of forest in the Peruvian Amazon is as follows;
- £4000 if forest is harvested (sustainably) for fruits, latex and timber
- £600 if clear cut for commercial timber
- £90 if used for cattle pasture
9. Useful additional information can be obtained from the following web based sources:
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