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DEFORESTATION |
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Mass
extinction Extinction
is a natural component of evolution, but generally it's a rare event valued
at 1-10 species a year, instead the scientists estimate that in this century
the rhythms of extinction are increasing so much that annually it gets to a
thousand species at least. We are living in a period of mass extinction, an
evolutive upsetting of the diversity and of the composition of life in this
world. The paleontologists, by studying the fossil remains, have singled out
five events of mass extinction in a thousand million and a half of years ,
the last one happened 65 million years ago, in the end of Cretaceous with the
death of dinosaurs, but now the vegetable species suffer heavy losses without
precedent. In a study of 1997 on a world basis the World Conservation Union
has pointed out that one out of eight of the 240.000 vegetable species
considered, risks dying out. Together with other human activities the
greenhouse effect is a determinant for it, in fact tha data drawn from
research works in the tropical forests all over the world, indicate that the
rhythm with which the trees of the pluvial forests die and grow, called rate
of change, has been constantly increasing since the 50's. This means that the
observed forests are becoming younger and dominated by trees and creepers
growing rapidly and living shortly, that is exactly the kinds of plants which
thrive in habitat rich in carbon dioxide and exposed to atmospheric extreme
events. Without drastic reductions of CO2 emissions, the changing rates of
the forests will increase some more probably and they might lead to
extinction many species of tropical trees of hardwood and growing slowly
which are not able to compete in habitat too rich in carbon. |
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NASA deforestation Rio Grande Bolivia NASA deforestazione Brasil |
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Clear
emission of CO2 Without
repeating what we have already said in the pages on "humus",
"greenhouse effect", "the proposal", we must underline,
according to studies of the IPCC, that the deforestation and other uses of
the ground at the Tropics emit in the atmosphere 1,6 thousand millions of
tons of CO2 (weight in carbon); they represent almost the 50% as to 3,3
thousand millions of tons of CO2 which every year are added clear to the
atmosphere. Therefore by a correct management at international level of the
biosphere present both on the earth surface and inside the ground, we'll be
able to have in the middle period an important contribution to the solution
or the attenuation of the greenhouse effect. |
