http://www.enn.com/news/2003-09-24/s_8723.asp
Scientists
see Antarctic vortex as drought maker
Wednesday, September
24, 2003
By Michael Byrnes, Reuters
SYDNEY - Australia
may be facing a permanent drought because
of an accelerating vortex of winds whipping around the Antarctic
that threatens to disrupt rainfall, scientists said on Tuesday.
Spinning faster and
tighter, the 100-mile (160 km) -an-hour
jetstream is pulling climate bands south and dragging rain
from Australia into the Southern Ocean, they say. They
attribute the phenomenon to global warming and loss of
the ozone layer over Antarctica.
"This is a very
serious situation that we're probably not
confronting as full-on as we should," said Dr. James Risbey
of the Center for Dynamical Meteorology and Oceanography at
Melbourne's Monash University. "There has been real added
impetus here in Australia to try to study (the wind vortex)
because we've been faced with an almost precipitous rainfall
decline, particularly in the southwest of Western Australia,"
Risbey said.
Australia, one of the
world's top agricultural supply nations,
has just been through its worst drought in 100 years. Risbey
and other Australians are part of an international band of
scientists and meteorologists focusing on the vortex as an
explanation for declining rainfall.
Rainfall has declined
by nearly 20 percent in the past
seven years over parts of southwestern Western Australia,
through to Victoria and into southern New South Wales state,
Risbey said. At the same time, temperatures have been rising
in Australia by about one degree Celsius over the past 50 years,
requiring more rain to fall just to keep the status quo.
Spinning Faster
Australian scientists
from the Bureau of Meteorology,
the Commonwealth Scientific and Industrial Research
Organisation (CSIRO), and Monash University are working
with the U.S. Office of Oceanic and Atmospheric Research
and the British Antarctic Division on the Antarctic vortex.
Focusing on the vortex
for only the past few years,
they have quantified increased velocity of the wind
spin by measuring pressure differences between high
latitudes over the Antarctic continent and mid latitudes
in the Southern Ocean near Australia. A cooling polar
area and warming elsewhere is spinning the vortex faster,
which in turn pulls winds and pressure belts that
deliver Australia's winter and spring rains southward.
Australia's 2002/03
drought, the worst in 100 years and
the cause of shortages of a wide variety of some of the
world's largest supplies of bulk farm foods, was too
extensive to blame on the Antarctic vortex. But a
long-standing drought in the southwest corner of
Western Australia state could be a foretaste of
more extensive drought yet to come in Australia,
Risbey said.
Most worrying is that
this could be more or less
permanent, scientists say. Water resource managers
were already treating the rainfall decline in southwest
Western Australia as permanent. Melbourne was now in a
seven-year drought, while New South Wales has had
declining rainfall for the past 50 years or so, Risbey
said.
"It is consistent
with ... the polar vortex," he said.
Scientists say Australian
agriculture would be able
to cope with a 15 to 20 percent drop in rainfall,
although farmers may not agree. But changed management
and consumption will be necessary, possibly not only
in southern Australia but also in parts of South America,
South Africa, and New Zealand.
###
