That Seas Soak Up Less Greenhouse Gas
By Andrew Woodcock
22 October, 2007
oceans’ ability to act as a “carbon sink” soaking
up greenhouse gases appears to be decreasing, research shows, leading
to new fears about global warming.
Measurements of the North
Atlantic taken by British scientists over the decade from the mid-1990s
to 2005 show the level of carbon dioxide in its waters fell by about
half over that time.
One of the authors of the
study, published on Saturday in a paper for the Journal of Geophysical
Research, said the change may have been triggered by climate change
and may also accelerate the process by leaving more CO2 in the atmosphere.
Natural processes mean the
amount of CO2 in the atmosphere is reduced when the gas dissolves into
the waters of the oceans which cover much of the surface of the earth,
turning them into vast “sinks” storing the carbon safely.
But the new study suggests
the amount of carbon dioxide entering the oceans is declining, possibly
because warmer global weather has heated the water near the surface.
Professor Andrew Watson,
of the school of environmental sciences at the University of East Anglia,
said there was no known means to artificially reverse the change.
As the 90,000 measurements,
taken automatically by merchant ships as they criss-crossed the Atlantic,
had been gathered for only a decade, it was too early to be certain
whether they reflected a natural variation in CO2 levels or a man-made
trend which could be expected to continue, Professor Watson cautioned.
He acknowledged that the
processes driving the change were not yet known with certainty. “To
be perfectly honest, we don’t know,” he told BBC radio.
“We suspect that it is climactically driven, that the sink is
much more sensitive to changes in climate than we expected.
“Therefore, if you
have a series of relatively warm winters, the ocean surface doesn’t
cool quite so much, you don’t get so much subsurface water formed
and so the CO2 is not being taken down into the deep water.”
He warned that the process
may fuel climate change.
“It will be a positive
feedback, because if the oceans take up less CO2 then CO2 will go up
faster in the atmosphere and that will increase the global warming.”
There have been proposals
to increase the oceans’ capacity to absorb CO2 by “fertilizing”
them with iron or by building a network of millions of pipes to circulate
water from deeper levels far below the surface.
But Professor Watson warned
this would have little effect.
Another proposal to alter
the weather has been made by US and Israeli scientists, who have revealed
plans to weaken hurricanes and steer them off course to prevent tragedies
such as Hurricane Katrina. The $US41 billion of damage done to New Orleans
in 2005 has spurred two rival teams of climate experts to step up their
efforts to enable people to play God with the weather.
Under a scheme proposed by
the Massachusetts Institute of Technology, aircraft would drop soot
into the near-freezing cloud at the top of a hurricane, causing it to
warm up and so reduce wind speeds. Computer simulations of the forces
at work in the most violent storms have shown that even small changes
can affect their paths - enabling them to be diverted from big cities.
Last month scientists at
the Hebrew University of Jerusalem said they had simulated the effect
of sowing clouds with microscopic dust to cool the hurricane’s
base, also weakening it.
Copyright © 2007. The
Sydney Morning Herald.
Share Your Insights
it! And spread the word!
Here is a unique chance to help this article to be read by thousands
of people more. You just Digg it, and it will appear in the home page
of Digg.com and thousands more will read it. Digg is nothing but an
vote, the article with most votes will go to the top of the page. So,
as you read just give a digg and help thousands more to read this article.