Greenhouse Gases
'Do Warm Oceans'
By Paul Rincon
18 February, 2005
BBC
Scientists
say they have "compelling" evidence that ocean warming over
the past 40 years can be linked to the industrial release of carbon
dioxide.
US researchers compared
the rise in ocean temperatures with predictions from climate models
and found human activity was the most likely cause.
In coming decades,
the warming will have a dramatic impact on regional water supplies,
they predict.
Details of the study
were released at a major science meeting in Washington DC.
The conference is
the annual gathering of the American Association for the Advancement
of Science (AAAS).
"This is perhaps the most compelling evidence yet that global warming
is happening right now and it shows that we can successfully simulate
its past and likely future evolution," said lead author Tim Barnett,
of the climate research division at the Scripps Institution of Oceanography
in San Diego, California.
"If you take
this data and combine it with a decade of earlier results, the debate
about whether or not there is a global warming signal here and now is
over at least for rational people."
The team fed different
scenarios into computer simulations to try to reproduce the observed
rise in ocean temperatures over the last 40 years.
They used several
scenarios to try to explain the oceanic observations, including natural
climate variability, solar radiation and volcanic emissions, but all
fell short.
"What absolutely
nailed it was greenhouse warming," said Dr Barnett.
This model reproduced
the observed temperature changes in the oceans with a statistical confidence
of 95%, conclusive proof - say the researchers - that global warming
is being caused by human activities.
Regional water supplies
will be dramatically affected by climate change in the decades immediately
ahead, say the team.
The western US is
already experiencing water shortages and research suggests that the
region could face a water crisis within 20 years.
In the South American
Andes and western China, millions of people could be left without adequate
water during the summer due to accelerated melting of glaciers.
"If the snow
pack melts sooner, and if societies don't have the ability catch all
of that water, they're going to end up with water shortages in the summer,"
Dr Barnett explained.
According to the
Scripps researcher, political leadership was now needed to avert a global
disaster.
"Hopefully
we can get the US cranked around in that direction. I think the first
thing to do is figure out the global warming-related problems we have
ahead of us around the world.
"Unless we
know what we're dealing with, I think it's going to be pretty hard to
fix it."