Ook dat nog: "Sea absorbing less CO2, scientists discover"

[Henk Elegeert]

REPLY TO: D66 at nic.surfnet.nl

http://www.guardian.co.uk/environment/2009/jan/12/sea-co2-climate-japan-environment
"
Sea absorbing less CO2, scientists discover

    * David Adam, environment correspondent
    * The Guardian, Monday 12 January 2009
    * Article history

Scientists have issued a new warning about climate change after
discovering a sudden and dramatic collapse in the amount of carbon
emissions absorbed by the Sea of Japan.

The shift has alarmed experts, who blame global warming.

The world's oceans soak up about 11bn tonnes of human carbon dioxide
pollution each year, about a quarter of all produced, and even a
slight weakening of this natural process would leave significantly
more CO2 C02 in the atmosphere. That would require countries to adopt
much stricter emissions targets to prevent dangerous rises in
temperature.

Kitack Lee, an associate professor at Pohang University of Science and
Technology, who led the research, says the discovery is the "very
first observation that directly relates ocean CO2 uptake change to
ocean warming".

He says the warmer conditions disrupt a process known as "ventilation"
- the way seawater flows and mixes and drags absorbed CO2 from surface
waters to the depths. He warns that the effect is probably not
confined to the Sea of Japan. It could also affect CO2 uptake in the
Atlantic and Southern oceans.

"Our result in the East Sea unequivocally demonstrated that oceanic
uptake of CO2 has been directly affected by warming-induced weakening
of vertical ventilation," he says. Korea argues that the Sea of Japan
should be renamed the East Sea, because it says the former is a legacy
of Japan's military expansion in the region.

Lee adds: "In other words, the increase in atmospheric temperature due
to global warming can profoundly influence the ocean ventilation,
thereby decreasing the uptake rate of CO2."

Working with Pavel Tishchenko of the Russian Pacific Oceanological
Institute in Vladivostok, Lee and his colleague Geun-Ha Park used a
cruise on the Professor Gagarinskiy, a Russian research vessel, last
May to take seawater samples from 24 sites across the Sea of Japan.

They compared the dissolved CO2 in the seawater with similar samples
collected in 1992 and 1999. The results showed the amount of CO2
absorbed during 1999 to 2007 was half the level recorded from 1992 to
1999.

Crucially, the study revealed that ocean mixing, a process required to
deposit carbon in deep water, where it is more likely to stay, appears
to have significantly weakened.

Announcing their results in the journal Geophysical Research Letters,
the scientists say: "The striking feature is that nearly all
anthropogenic CO2 taken up in the recent period was confined to waters
less than 300 metres in depth. The rapid and substantial reduction ...
is surprising and is attributed to considerable weakening of
overturning circulation."

Corinne Le Quéré, an expert in ocean carbon storage at the University
of East Anglia, said: "We don't think the ocean is just going to
completely stop taking our carbon dioxide emissions, but if the effect
weakens then it has real consequences for the atmosphere."
"

Ook dat nog ...

Henk Elegeert

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