Dramatic Changes
In Southern Ocean, Fear Climate Link
By AFP
18 February, 2005
Agence France
Presse
Scientists have discovered dramatic changes
in the temperature and salinity of deep waters in the Southern Ocean
that they warn could have a major impact on global climate.
Expedition leader
Steve Rintoul of Australia said his multinational team of researchers
had found that waters at the bottom of the Southern Ocean were significantly
cooler and less salty than they were 10 years ago.
He said the size and speed of the changes surprised scientists, who
have long believed deep ocean waters underwent little temperature change,
and could indicate a slowdown in the flow of deep water currents.
"Ocean circulation
is a big influence on global climate, so it is critical that we understand
why this is happening and why it is happening so quickly," Rintoul
said after he and his team docked at Hobart on the Australian island
state of Tasmania.
"The surprise
was just how rapidly the deepest parts of the ocean are changing, at
depths of four or five kilometers (13,200-16,500 feet) below the sea
surface," Rintoul said.
"Whether its
a natural cycle that takes place over many decades, or it's climate
change, it's an indication that the deep ocean can respond much more
rapidly to changes that are happening near the surface than we believed
possible," he said.
The expedition sampled
3,000 kilometers of the Southern Ocean basin during an eight-week expedition
aboard the Australian Antarctic Division's research ship Aurora Australis.
Their findings added
new urgency to the study of climate change, Rintoul said.
"It's another
indication that the climate is capable of changing and is changing now,"
he said.
"What we need
to do is sort out if this is human-induced change and if so, how rapidly
is the climate going to change and what will the impacts of that change
be?" he said.
The new findings
emerged a day after the UN's Kyoto Protocol on climate change came into
force. The treaty aims to cut production of so-called greenhouse gases
believed responsible for a warming of the Earth's climate.
During its expedition,
the Australian-led team released 19 free-floating ocean robots known
as Argo floats, which are designed to drift with ocean currents to better
measure temperature and salinity.
The floats, part
of an international ocean-monitoring effort, drift about 2,000 meters
(6,600 feet) underwater and surface every 10 days to deliver findings.
Rintoul said the
Argos would provide a huge boost to climate research.
"They will
revolutionize how we understand the ocean, in particular to determining
climate change and shorter climate cycles," he said.
"One of the
real challenges for us when we try to answer the question of 'is this
climate change?' is that we only have measurements from a few southern
snapshots," he said.
"We haven't
measured it continuously in time so it's hard for us to tell the difference
between a cycle, something moving up and down, and a long-term trend.
That's the real challenge."
Copyright ©
2005 Agence France Presse