Os dados do centro de análise da NASA, Colorado, são claros. Mostram que o nível de gelo do Pólo Norte e no Pólo Sul atingiu, este ano, os mínimos de sempre, pelo menos desde que há registos.
Mar Árctico, gelo
Arctic sea ice
créditos:NASA Goddard's Scientific Visualization Studio/L. Perkins
Line graphs plot monthly deviations &overall trends
in polar sea ice from 1979 to 2017
Credits: Joshua Stevens/NASA Earth Observatory
The ice floating on top of the Arctic Ocean and surrounding seas shrinks in a seasonal cycle from mid-March until mid-September.
As the Arctic temperatures drop in the autumn and winter, the ice cover grows again until it reaches its yearly maximum extent, typically in March.
The ring of sea ice around the Antarctic continent behaves in a similar manner, with the calendar flipped: it usually reaches its maximum in September and its minimum in February.
Antarctic sea ice
Credits: NASA Goddard's Scientific Visualization Studio/L. Perkins
“We started from a low September minimum extent,” said Walt Meier, a sea ice scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “There was a lot of open ocean water and we saw periods of very slow ice growth in late October and into November, because the water had a lot of accumulated heat that had to be dissipated before ice could grow. The ice formation got a late start and everything lagged behind – it was hard for the sea ice cover to catch up.” Read more
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