Palm trees and forests?:
A new future for the Antarctic
Palm trees could grow in the Antarctic if climate change continues
unabated, new research has shown - just as they did 55 million years
ago.
A study has found that similar trees grew in the region during the
early Eocene epoch, when the area had a near-tropical climate with
frost-free winters, even in the polar darkness. Global levels of the
principal greenhouse gas, carbon dioxide, were nearly three times as
high then as today.
It has long been known that the start of the Eocene was a "thermal
maximum", one of the hottest periods in Earth's history, and that
Antarctica as a continent would have been ice-free and much warmer than
at present.
But the new findings, based on sediment cores taken from the
Antarctic seabed, have enabled the first-ever detailed reconstruction of
its environment and thus its climate.
This was previously impossible because any Eocene sediments remaining
on land were destroyed by the subsequent glaciation of Antarctica, or
covered with thousands of feet of ice. But pollen grains were washed,
blown or transported by insects on to the shallow coastal shelf, where
they settled in the mud and were preserved for 50 million years.
Analysis of the pollen in the sediment reveals two plant
environments, one being a lowland, coastal warm rainforest similar to
that in northern Australia or New Guinea, dominated by palms, tree-ferns
and members of the Bombacoideae family, which include the famous baobabs
of Africa.
The other was an upland, mountain forest region, further into the
continent's interior, with beech trees and conifers. The presence of the
various plants indicates that temperatures on the Antarctic coast were
around 16C and summers reached a balmy 21C. Antarctica was in nearly the
same position it now is, over the South Pole, so the winter months would
have been dark, like today, but the presence of the flora indicates it
was warmer than 10C, even during the coldest and darkest months.
The study was carried out by a team of 36 scientists involved in the
Integrated Ocean Drilling Research Program, a project set up to research
the early Eocene climate.
Off the coast of Wilkes Land, they dropped a drill through 4km of
water, then bored 1km into the ocean floor to collect the sediment
samples.
Dr James Bendle, of the University of Glasgow, one of the authors of
the study, said: "The samples are the first detailed evidence we have of
what was happening on the Antarctic during the Eocene, this vitally
important time.
"Our work carries a sobering message. Carbon dioxide levels were
naturally high in the early Eocene, but today CO2 levels are rising
rapidly through human combustion of fossil fuels and deforestation.
Atmospherically speaking we are heading rapidly back in time towards the
Eocene."
The vegetation of Antarctica today could not be more different from
its state in the Eocene epoch. There are no trees and shrubs on the
continent, and only two species of flowering plants, pearlwort and hair
grass, are found along the western side of the Antarctic Peninsula.
But lower plants are comparatively plentiful: there are more than 300
species of lichens and about 100 species of mosses.
The continent of Antarctica, with 5.4 million square miles, 98 per
cent of it ice, is the fifth largest after Asia, Africa, North America
and South America.
- The Independent
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