May
31, 2007
WEST
AFRICAN OCEAN
SEDIMENT CORE LINKS MONSOONS TO GLOBAL CLIMATE
EVOLUTION
Monsoons,
the life-giving, torrential rains of Asia and Africa, have an ancient,
unsuspected connection to previous Ice Age climate cycles, according to
scientists at the University
of California,
Santa Barbara,
and at Kiel
University
in Germany.
Analyzing
a 120-foot sediment core from the Gulf
of Guinea
in equatorial West Africa
recovered by a German research expedition, UC
Santa Barbara postdoctoral scholar Syee Weldeab and paleoclimatologist
David
Lea have revealed 155,000 years of continuous monsoon history.
“It is the
longest, most detailed record of West African monsoons that has ever
been
reconstructed,” said Lea. The find captured several Ice Age
climate cycles.
From
chemical data locked into fossil plankton shells, the researchers
documented
how the strength of ancient monsoons is directly tied to two factors:
the
Northern Hemisphere’s climate shifts due to the expansion and
contraction of
the European and North American continental ice sheets, and the amount
of local
solar radiation hitting the African region.
"This
is the first study to definitively tie together the influence of these
two
factors over several climate cycles," said Lea, who has published the
collaborative results in the June 1 issue of the journal Science under
the
heading "155,000 Years of West African Monsoon and Ocean Thermal
Evolution." He noted that there is "a dramatic resurgence of the West
African monsoon" at the end of each glacial cycle.
The study's
importance to the
modern climate, said Lea, lies in its "demonstration of the sensitivity
of
the monsoon region to global climate conditions." With hundreds of
millions of people dependent on subsistence agriculture in these
regions, he
said, "Insights from the study of ancient climate cycles will lead to
more
confident predictions of how monsoon patterns will evolve in a future
warmed by
greenhouse gases."
##
Contact:
Vic
Cox
University
of California-Santa Barbara
805-893-4765
vic.cox@ia.ucsb.edu
This
text derived from:
http://www.ucsb.edu
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