By Dr. Heather Stein -
Dr. Wallace S. Broecker, an eminent geologist at Columbia's Earth Science Institute, may challenge the oft-cited claim that the world's rainforests are responsible for 20% of the global oxygen supply, but there is no doubt that the loss of our rainforests to deforestation threatens all of us.
Broecker points out that the "extra oxygen" produced by these ecosystems with year-round humid and warm conditions is offset by the other life forms in the environment -- animals, insects, fungi, and of course bacteria. The biodiversity of rainforests is, in fact, what makes them so very special.
Most researchers estimate that as much as 50% of the world's plants and animals around found in rainforest climates -- with millions still to be discovered! What do such diverse flora and fauna mean for us humans? Since the seventeenth century, the tropical plant quinine has been used as an effective treatment for malaria. Indeed, 70% of known cancer-fighting plants exist in rainforests, and clinical trials continue to investigate treatments for HIV, Alzheimer's, and other plagues of the modern age. Anthropologists agree that the only pre-contact societies remaining on our planet continue their traditional modes of existence under the forest canopies relying on plants and a way of life not possible elsewhere.
Without the rainforests, however, we lose more than just biodiversity. The root structures of millions of trees anchor the soil to the landscape and prevent soil erosion. Without the trees, over 75 inches a month of rainfall results in landslides that destroy and kill.
Rainforests exist outside the tropics. Indeed, much of the Northwestern coast of North America is temperate rainforest -- California's Giant Redwoods are an iconic example of the large, coniferous trees that dominate these small pockets of heavy rainfall in cooler, coastal landscapes across the world.
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