This is a podcast of Scripps Institution of Oceanography at UC San Diego.
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Global warming is not the only consequence of our fossil fuel use.
While nearly half the carbon dioxide produced by humans remains in
atmosphere, the oceans absorb about a third.
There, researchers like marine biologist Victoria
Fabry and marine chemist Andrew Dixon are discovering
a new problem that threatens entire marine ecosystems.
Scientists call ocean acidification
the other CO2 problem. Ocean acidification has in fact been called
the other CO2 problem.
People are very much aware, I think,
that if you put CO2 in the atmosphere
it causes global warming, but another problem is also ocean acidification.
When you put CO2 into the ocean it lowers the pH
of the sea water and it also
decreases the carbonate ion concentration,
which is an important building block in the shells
and calcium carbonate skeletons of many different organisms.
Once it was really apparent that CO2 was
increasing in the atmosphere and this is really work made
clear by the work of Charles David Keeling here at Scripps.
He also pointed out that
of the total amount of CO2 that was being produced by burning fossil fuels
only about 40% was remaining in the atmosphere.
The rest was going somewhere else: the oceans and
land plants. People realize that if it was going to dissolve in the oceans it was
going to have these chemical changes. The first papers I saw discussing this
were published in about 1973, but at that time
people did not see this as a problem where
the concentration of carbonate mattered directly. What they saw was
that if you got to a certain level where calcium carbonate would start to
dissolve, that is carbonate ion concentration was so low
that the mineral would dissolve, then it would be a problem
and it was above that then it wouldn't be a problem. That's how people viewed it.
We've come to realize and this is through experiments that started in the
1990s and through the years of this century, but in actual fact
these effects are gradual. That is,
if you reduce the carbonate ion concentration there is an effect
even though you haven't yet got to the low levels that would be required to
have calcium carbonate dissolve.
Scripps scientists are using the data plotted in the famous Keeling curve
and the rich archives of ocean data collected by the institution
to put the problem of ocean acidification in context.
Other key resources are the samples at the ocean water prepared in Dixon's lab
that have helped to create over the past 20 years
the reference standard for measurement of carbon dioxide
and alkalinity levels in seawater.
Today, Dixon's lab bottles about 4,500 samples a year for distribution to lab
around the world.
Scripps is emerging as a center ocean acidification study
by drawing on the expertise of scientists in several disciplines.
Last November, Scripps physical oceanographer,
Uwe Send, and Scripps biological oceanographer,
Mark Ohman, joined a variety of collaborators
including scientists from NOAA to add carbon dioxide sensors
to moorings deployed off the Southern California coast.
There are plans to deploy two more moorings this year
in San Diego and near the California-Oregon border
and to launch lab experiments to observe how rising acidity
affects the development of shelled organisms. This is a very
interdisciplinary
problem, the issue of ocean acidification. It involves biology from
molecular and genomic techniques and scales all the way to
ecosystems and it involves of course the chemistry,
physical environment, and modeling. All of that
comes together here at Scripps. The problem of ocean acidification
is a very large one because it involves climate
impacts on ocean environment on a very large scale.
It requires interdisciplinary research
drawing on the expertise of different groups of people.
The Mooring project, coordinated by myself and
Uwe Send with the collaborations of many other
colleagues, is one element. This is the observational
ocean element of an ocean acidification research program.
Other kinds of research that are needed
involved laboratory experimental work where we very carefully control
the environment and look at the rates of calcification and
growth of calcifying organisms and a variety of different
model efforts, mathematical models,
to project the future state of the system in time.
So we're contributing the insight to ocean measurement
side to this complementary effort.
Much more research is needed to know when, where,
and to what extent acidification trends will affect ocean waters.
But the indications researchers have observed suggest we cannot allow a
generation to past
before deciding what needs to be done. It takes about a thousand years or more,
a few thousand years, for things to return back to how they were
before we put the CO2. Even if we removed all the CO2 from the atmosphere
and we put in extra, it would still take a few thousand years because the oceans
only mix slowly. Its as though you imagine a cup of tea and it's being stirred
once every 1000 years.
Some of the big unknowns for the ocean acidification is, will organisms adapt
or not?
Some of them probably will adapt, but others may in fact not have time-- the
conditions are changing so
rapidly. That is a key point with ocean acidification.
Humans are increasing atmospheric CO2 concentration
at such a rapid rate, it doesn't give many
organisms time to adapt particularly in the high latitudes
where they can face corrosive conditions
in a matter of decades or even along our coast.
We simply don't know at this point. It's a big unknown.
This has been a presentation of
Scripps Institution of Oceanography at UC San Diego.