Global warming: new evidence found in tropical ice cores explains collapse of ancient civilisations


Indiana Thompson and high altitude research: Lonnie Thompson is
a geophysicist at Ohio State University in Columbus and a pioneer in
the study of tropical glaciers. His adventures while gathering ice
cores at high altitude have led colleagues to describe him as “the
closest living thing to Indiana Jones”. Thompson and his work are the
subjects of Thin Ice: Unlocking the secrets of climate in the world’s highest mountains by Mark Bowen published by Henry Halt and Company (ISBN 0805064435, $30).

Pioneering on a small budget: The switch from polar to tropical
ice was triggered by a British colleague called John Mercer who had
produced atlases of the glaciers of the world. Thompson started
wondering why no one was taking cores from them. He showed some
pictures of Quelccaya, a big ice cap in the Peruvian Andes, to the
National Science Foundation and received $7000 funding, which was about
enough to get there and, despite misadventures, start research.

Research record shows historical effects of climate change:
Thompson says Mercer, now deceased, was the first person to suggest
that the west Antarctic ice sheet could collapse with global warming.
What do the tropical cores show? Quelccaya, Thompson’s first glacier,
is the one he keeps returning to, as it continues to provide unique
information. It shows the 20th-century warming very clearly in the
record of oxygen isotopes preserved in the ice. It also provided the
first tropical record of the little ice age between the 14th and 19th
centuries, and it records the three decades of drought around AD 600
that probably finished off the pre-Colombian Moche empire. Quelccaya
also contains a record of El Nino climate variations.

Drought 4200 years ago destroys ancient civilisations: Another
big discovery was a huge spike in the amount of dust in many tropical
ice cores 4200 years ago. The dust seems to signify widespread drought
and desertification. It coincided with the collapse of several
civilisations, including the Akkadian empire in Mesopotamia and a
crisis in Egypt, where writing on ancient tombs records drought, mass
migrations and sand dunes crossing the Nile.

New Scientist, 26/11/2005, p. 47

Source: Erisk –



New Scientist, 26/11/2005, p. 47

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