Regardless Of Global Warming Rising Co2 Levels Threaten Marine Life
Pastor Dale Morgan
Regardless Of Global Warming Rising Co2 Levels Threaten Marine Life*
The addition of carbon dioxide into the oceans also affects the
carbonate mineral system by decreasing the availability of carbonate
ions. Calcium carbonate is used in forming shells. With less carbonate
ions available, the growth of corals and shellfish could be
significantly reduced.
by Staff Writers
Champaign, IL (SPX) Mar 11, 2007
Like a piece of chalk dissolving in vinegar, marine life with hard
shells is in danger of being dissolved by increasing acidity in the
oceans. Ocean acidity is rising as sea water absorbs more carbon dioxide
released into the atmosphere from power plants and automobiles. The
higher acidity threatens marine life, including corals and shellfish,
which may become extinct later this century from the chemical effects of
carbon dioxide, even if the planet warms less than expected.
A new study by University of Illinois atmospheric scientist Atul Jain,
graduate student Long Cao and Carnegie Institution scientist Ken
Caldeira suggests that future changes in ocean acidification are largely
independent of climate change. The researchers report their findings in
a paper accepted for publication in the journal Geophysical Research
Letters, and posted on its Web site.
"Before our study, there was speculation in the academic community that
climate change would have a big impact on ocean acidity," Jain said. "We
found no such impact."
In previous studies, increasing levels of carbon dioxide in the
atmosphere led to a reduction in ocean pH and carbonate ions, both of
which damage marine ecosystems. What had not been studied before was how
climate change, in concert with higher concentrations of carbon dioxide,
would affect ocean chemistry and biology.
To investigate changes in ocean chemistry that could result from higher
temperatures and carbon-dioxide concentrations, the researchers used an
Earth-system model called the Integrated Science Assessment Model.
Developed by Jain and his graduate students, the model includes complex
physical and chemical interactions among carbon-dioxide emissions,
climate change, and carbon-dioxide uptake by oceans and terrestrial
ecosystems.
The ocean-surface pH has been reduced by about 0.1 during the past two
centuries. Using ISAM, the researchers found ocean pH would decline a
total of 0.31 by the end of this century, if carbon-dioxide emissions
continue on a trajectory to ultimately stabilize at 1,000 parts per million.
During the last 200 years, the concentration of atmospheric carbon
dioxide increased from about 275 parts per million to about 380 parts
per million. Unchecked, it could surpass 550 parts per million by
mid-century.
"As the concentration of carbon dioxide increases, ocean water will
become more acidic; which is bad news for marine life," Cao said.
"Fortunately, the effects of climate change will not further increase
this acidity."
There are a number of effects and feedback mechanisms built into the
ocean-climate system, Jain said. "Warmer water, for example, directly
reduces the ocean pH due to temperature effect on the reaction rate in
the carbonate system. At the same time, warmer water also absorbs less
carbon dioxide, which makes the ocean less acidic. These two climate
effects balance each other, which results in negligible net climate
effect on ocean pH."
The addition of carbon dioxide into the oceans also affects the
carbonate mineral system by decreasing the availability of carbonate
ions. Calcium carbonate is used in forming shells. With less carbonate
ions available, the growth of corals and shellfish could be
significantly reduced.
"In our study, the increase in ocean acidity and decrease in carbonate
ions occurred regardless of the degree of temperature change associated
with global warming," Jain said. "This indicates that future changes in
ocean acidity caused by atmospheric carbon-dioxide concentrations are
largely independent of climate change."
That's good news. The researchers' findings, however, call into question
a number of engineering schemes proposed as mitigation strategies for
global warming, such as lofting reflective balloons into the
stratosphere or erecting huge parasols in orbit. By blocking some of the
sunlight, these devices would create a cooling effect to offset the
warming caused by increasing levels of greenhouse gases.
"Even if we could engineer our way out of the climate problem, we will
be stuck with the ocean acidification problem," Caldeira said. "Coral
reefs will go the way of the dodo unless we quickly cut carbon-dioxide
emissions."
Over the next few decades, we may make the oceans more acidic than they
have been for tens of millions of years, Caldeira said. And that's bad
news.