DEGELO NA ANTÁRTIDA SE INTENSIFICA
Autor: Dorival Pinheiro | Publicado: 2013-04-26T13:27:00-03:00

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Um
estudo divulgado nesta segunda-feira indica que o degelo atual do verão
antártico está dez vezes mais rápido que há 600 anos. 





De
acordo com o trabalho, publicado na revista especializada "Nature Geoscience",
esse fenômeno se intensificou ainda mais nos últimos 50 anos. 




Para
chegar a esses resultados, os cientistas perfuraram, a uma profundidade de 364
metros, calotas da ilha James Ross, no norte da geleira antártica. 




O
objetivo dos pesquisadores era medir as temperaturas de centenas de anos que
ficaram registradas no gelo. 




As
sucessivas camadas na geleira revelam o movimento de degelo e de congelamento
que ocorreu, e ao medir a espessura destas camadas, os cientistas foram capazes
de comparar as variações de temperatura nas camadas mais superficiais com as do
núcleo de gelo ao longo dos últimos mil anos. 




Constatamos
que, há 600 anos, havia condições mais frias na península antártica e uma menor
quantidade de gelo derretido", disse Nerilie Abram, líder do trabalho e
pesquisadora do British Antarctic Survey de Cambridge, no Reino Unido. 




Naquela
época, as temperaturas eram aproximadamente 1,6 grau Celsius menor que as
registradas no fim do século 20, e a proporção de neve que derretia a cada ano
e depois voltava a congelar era de 0,5%, segundo Abram. 




"Hoje,
a quantidade de neve que derrete a cada ano é dez vezes maior." 




Apesar
do aumento regular das temperaturas que ocorre há centenas de anos, o degelo se
intensificou a partir da metade do século 20, afirma o novo estudo. 




Isso
significa que o aquecimento na Antártida alcançou um nível em que até leves
aumentos de temperatura podem provocar uma forte aceleração do degelo.&nbsp;

Extraido da Folha On Line