More Climate doom and Gloom

[Guest guest]

Bulk of greenhouse gases swallowed by oceans and other stories

 

 

 

Friday, August 13, 2004

Adapted by Megan Mansell Williams and Kathleen M. Wong, California Academy of

Sciences

 

 

 

Bulk of Greenhouse Gases Swallowed by Oceans

The sea has sucked up about half the carbon dioxide that humans have pumped out

since the start of the Industrial Age, two new studies report in the journal

Science.

 

The researchers, led by Chris Sabine of the National Oceanic and Atmospheric

Administration, spent 10 years gathering water samples from the world's oceans

and another five years analysing their results. They found that the oceans' good

deed comes at great cost to marine wildlife.

 

When CO2 dissolves in seawater, it forms an acid that eats away at the shells

and skeletons of some marine organisms. With no end in sight to the greenhouse

gases spewed out when humans burn fossil fuels, Sabine warns that the oceans

could become acidic enough to slash the growth of corals and plankton in half.

Such a catastrophe would throw entire food chains out of whack, severely

disrupting marine ecosystems. The study demonstrates that actively pumping CO2

into the oceans, a method suggested to combat global climate change, would have

a major biological impact beneath the blue.

 

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July 16, 2004

 

 

 

The Clio pyramidata pteropod mollusk, from the subarctic Pacific Ocean, is among

the many sea creatures at risk from increasing levels of carbon dioxide in the

oceans.

 

Nearly half the carbon dioxide produced by humans over the past 200 years has

ended up in the world's oceans, changing their chemistry and potentially

threatening marine organisms that make up the bottom of the marine food chain,

scientists have found.

 

A newly-released survey conducted during the 1990s in the Pacific, Atlantic and

Indian oceans reveals that over the two centuries, the atmosphere and oceans

have been the primary repositories for the greenhouse gas.

 

The reason, scientists suspect, is that deforestation and the spread of

agriculture during that time reduced the ability of trees and other vegetation

to absorb carbon dioxide – a chief by-product of burning fossil fuels and a key

contributor to rising global temperatures.

 

The increasing concentrations of carbon dioxide in the world's upper oceans

could be hampering the ability of many phytoplankton to create protective

shells. Phytoplankton are microscopic plants that form the foundation of the

marine food chain. They grow abundantly around the world and are consumed by

zooplankton that, in turn, are preyed upon by larger marine animals.

 

" We might see that the structure of the food web will change, but what the

ultimate outcome will be we can't say, " said Victoria J. Fabry, a biologist at

California State University San Marcos, who contributed to a paper that

accompanies the carbon dioxide survey profiled in today's issue of the journal

Science.

 

Fabry found that the ability of many marine creatures to form shells will

decrease 25 percent to 45 percent if concentrations of atmospheric carbon

dioxide reach 700 to 800 parts per million.

 

Those levels of carbon dioxide are expected to be reached by the end of the

century if fossil fuel consumption continues unabated. Today's concentrations

are about 380 parts per million.

 

The landmark studies paint a complex picture of how the Earth's environment

cycles carbon dioxide among the land, atmosphere and oceans, and how humans have

complicated the story.

 

Researchers said much more study is needed before they can better understand how

carbon dioxide could be changing the oceans, and what that ultimately could mean

for marine life. But the findings so far, they said, provide the most complete

view to date of where carbon dioxide produced by humans since the Industrial

Revolution has gone.

 

The global ocean survey, co-sponsored by the National Science Foundation, the

National Oceanic and Atmospheric Association and the Department of Energy, was

unprecedented in scope and sophistication.

 

Scientists collected water samples from about 72,000 locations throughout the

Atlantic, Pacific and Indian oceans from 1989 to 1998 – providing 10 times more

observations and 10 times greater accuracy than a previous survey in the 1970s,

scientists said.

 

Earlier studies have shown that concentrations of carbon dioxide in the

atmosphere remained between 200 and 280 parts per million from 400,000 years ago

until global industrialization began in the 1800s.

 

Since then, scientists have estimated that fossil fuel burning, cement

manufacturing and other industrial activities have pumped 244 billion metric

tons of carbon dioxide into the atmosphere – raising concentrations of the

greenhouse gas in the air to the current levels of nearly 380 parts per million.

 

But that rise accounts for only about half the carbon dioxide humans have

produced over the past 200 years, and a fundamental question for scientists when

they embarked on the study was: How much of the missing gas ended up in the

oceans?

 

About 48 percent, the scientists have found.

 

The revelation that the planet's land surfaces – that is, trees and other

vegetation – had such a limited role in absorbing industrial carbon dioxide was

significant, scientists said yesterday during a news conference in Washington,

D.C.

 

Christopher Sabine, lead author and a researcher from NOAA's Pacific Marine

Environmental Laboratory in Seattle, said global deforestation and the spread of

agriculture in the 19th and early 20th centuries probably played key roles in

limiting the land's ability to absorb the gas.

 

Today, as farmland and other historically cleared areas have been reforested,

that trend is changing, he said.

 

That doesn't mean the oceans are taking in less of it.

 

The rise in atmospheric carbon dioxide has skyrocketed over the past 35 years,

and scientists around the world expect concentrations of the gas to keep

increasing.

 

As they do, the world's oceans will absorb even more carbon dioxide. In fact,

scientists said, they have filled only about one-third of their storage capacity

because it takes so long for oceans to circulate from top to bottom, carrying

carbon dioxide into deeper water. About 50 percent of carbon dioxide emissions

since 1800 are stored in the upper 10 percent of the world's oceans, the

scientists found.

 

" The oceans have a capacity to take up carbon dioxide for thousands of years, "

Sabine said.

 

But the more carbon dioxide the oceans take, the more ocean chemistry will

change.

 

As levels of the gas continue to rise in the upper oceans, concentrations of

carbonate ions will fall. Many marine organisms, including corals and many

plankton, draw carbonate ions from seawater to make calcium carbonate. Without

it, many forms of phytoplankton cannot form the shells that make up a key part

of their biology.

 

" As seawater carbon dioxide levels rise, " Fabry said, " the skeletal growth rates

of (shell-forming) plankton will be reduced. "

 

 

 

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Bruce Lieberman: (619) 293-2836; bruce.lieberman

[Guest guest]

and..

rising ocean temperatures will foster the relaese of more CO2 as well..

fun fun fun!!!