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| | IPCC Special Report on Emissions Scenarios |
 | | Even so the future is always unknowable and surprises are in store, as confirmed by a cursory review of the past history of population projections in which fundamental events were largely unforeseen (post-World War II baby boom, acquired immunodeficiency syndrome (AIDS) or the recent rapidity of fertility decline in developing countries). |
 | | World population reached 1 billion in 1804, 2 billion in 1927, 3 billion in 1960, 4 billion in 1974, and 5 billion in 1987, reaching the 6 billion level shortly before the millenium (UN, 1998). |
 | | World annual population growth rates probably averaged less than 0.6% during the 18th and 19th centuries, passed the 1% rate around 1920, and peaked at 2.04% in the late 1960s (UN, 1998). |
| www.grida.no /climate/ipcc/emission/051.htm (765 words) |
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