Arctic warming reverses cooling trend
An abrupt warming of the Arctic has reversed a cooling trend that
began about 8,000 years ago, according to a study published Thursday
which sheds light on the threat of rising sea levels and climate change.
Increased greenhouse gas emissions appear to have overridden the
natural cooling caused by a wobble in the Earth's axis which has been
gradually pulling the planet away from the Sun.
This wobble has cooled summer temperatures by an average of about 0.2
degrees Celsius per thousand years, the study published in the journal
Science found.
But Arctic temperatures began to rise at the beginning of the 20th
century even though the orbital cycle that produced the cooling
continued.
The result was summer temperatures that were about 1.4 degrees
Celsius warmer than they should have been by the year 2000, according to
the study which mapped Arctic temperatures for every decade of the past
2,000 years.
Temperatures for four of the last five decades were among the highest
on record. "This study provides us with a long-term record that reveals
how greenhouse gases from human activities are overwhelming the Arctic's
natural climate system," said co-author David Schneider of the
Colorado-based National Center for Atmospheric Research. AFP
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