London: Woolly mammoths helped to keep
the Earth warm by filling the atmosphere with methane 13,000 years ago, say scientists.
An international team, led by the University of
New Mexico, has claimed that mammoths, along with other large
plant eating mammals, may have created about 9.5 million tons
of the methane gas each year.
An analysis of ice cores has shown that when
they disappeared there was a huge fall in atmospheric methane,
which may have caused the last Ice Age, according to the
They found a "cold event" hit the Earth at the same
time as methane levels fell.
"The changes in methane concentration seem to be
unique. Decreased methane emissions caused by the extinction
of New World `megafauna` could have played a role," the
British quoted the scientists as saying.
Methane is a powerful greenhouse gas.
About 13,400 years ago the Americas were heavily
populated by large-bodied herbivores like mammoths, camelids
and ground sloths and had a richer array of animals than
present-day Africa. But 2,000 years later 80 per cent of them
Their disappearance, accounting for more than 114
lost species, came within 1000 years of the arrival of humans
in the New World, but experts disagree over whether hunters or
environmental changes were to blame.
The findings have been published in the latest edition
of the `Nature Geoscience` journal.