| Ocean Acidification Nov 13-14,
2006 |
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Questions and Answers |
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| Q: How does temperature affect the rate
at which ocean acidification occurs? - Bubba Cook |
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| Dr Scott Doney: For the most part, temperature
doesn’t
directly affect the rate of ocean acidification. But for corals
there may be synergistic effects (probably with a negative
impact) due to warming and acidification occurring at the same
time. For example, many recent coral bleaching events have
been linked to extreme high temperatures, and such episodes
may become more frequent under enhanced greenhouse warming. |
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| Q: Are there
any groups or nations that have been able to reduce ocean acidification?
- Thomas Stanley |
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Dr Richard Feely: Ocean
acidification is caused by excessive CO2 emissions from fossil-fuel
burning. Collectively, all the countries in the world release
about 7 billion metric tons of carbon as CO2 into the atmosphere
each year. The oceans take up about 2 billion tons of carbon
annually. This means that as long as we continue to release
excessive amounts of carbon dioxide into the atmosphere the
oceans will continue to undergo ocean acidification. Consequently,
no one group or nation can reduce ocean acidification. All
nations must work together to solve this problem.
Dr Carol Turley: I totally agree with Richard
Feely. This makes ocean acidification a compelling argument
to that of climate change to reduce our global CO2 emissions. |
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| Q: What
evidence is there that organisms can migrate or evolve to adapt
in changed conditions? - Katherine
Noonan |
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Dr Richard Feely: Right
now there is almost no information about how marine organisms
might migrate or evolve to avoid ocean acidification. However,
these are a considerable number
of examples of how marine organisms migrate as a result of
change climate, so we might expect to see similar responses
to low pH waters.
Dr Carol Turley: Yes, there is no evidence
at the moment so it’s pretty much guess work until we
get more results - but if we look at coral reefs which
will suffer from warming seas (causing coral bleaching) and
ocean acidification, we could argue that they may migrate away
from the tropics towards the higher latitudes to cooler waters – but
here the aragonite (the form of calcium carbonate they use
to make their skeletons) is less (because of ocean acidification) – so
in a sense they are being squeezed by temperature and ocean
acidification. |
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| Q: Does the study of
Ridgwell and Zeebe 2005 has done some links between co2 levels
in the past and the response of marine life using fossils or
records of some sorts? - Alexandra Amat |
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Dr Richard Feely: The
recent paper by Zachos et al (2004) in Science shows that during
the PETM about 55 ma ago, a large input of CO2 in the deep
ocean, presumably resulting from a massive methane release
(approximately 4000 GT C) caused an extensive shoaling of the
calcite saturation horizon in the deep sea followed by extinction
of some species of benthic forams. This example from the fossil
records indicate that marine organisms are indeed sensitive
to ocean acidification.
Dr Carol Turley: Yes, this is a very interesting
and powerful example (or analogue) of what we are doing now – the
major difference is that we are doing it even faster than
what occurred 55 millions years ago. |
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| Q: With the shallow,
tropical seas becoming more salty and the deeper, polar oceans
becoming more fresh, what will the implications of global warming
have on the results of this research? - Ellycia Kolieb |
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| Dr Scott Doney: The warming and freshening
of the upper ocean tend to make the water column more stable.
In the tropics and subtropics, this will reduce vertical mixing
that supplies nutrients and drives much of the biological productivity.
At polar latitudes, the freshening may actually increase overall
biological productivity because currently photosynthesis is
often limited by deep mixing that reduces the average amount
of light seen by phytoplankton. The biological impacts of ocean
acidification will be layered on top of these other physically
driven changes. |
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| Q: Is there a way to balance these findings
with the needs of developing nations? - Thomas Stanley |
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Dr Scott Doney: Some of the largest climate
change impacts on coastal and island developing nations will
likely be sea-level rise and the destruction of key local natural
resources such as coral reefs, which are important sources
of income via tourism and fishing.
Dr Carol Turley: A really good question and
a very political one. I think we need an international framework
on reducing CO2 emissions that incorporates reduction of emissions
by developed national (and ultimately all nations) and allows
the development of emerging nations. Carbon trading is one
method that may be useful that Europe introduced at the beginning
of this year. |
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| Q: How is it possible
to cut back on fossil energy - with China and India among others
growing rapidly. - Phil Kithil |
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| Dr Scott Doney: There are broadly three
approaches, all of which will need to be adopted by both the
developed world and China and India in order to make a large
impact on atmospheric CO2. These approaches are: increase energy
conservation and efficiency; transition to non-CO2 emitting
energy sources; sequester some of the CO2 from fossil fuel
use (e.g., into old oil and gas wells; replanted forests, etc.).
One argument is that if the developed world with there already
high standard of living and past CO2 emissions does not lead
on this effort, it is hard to expect the developing world to
potentially slow their economic growth (and increased standard
of living) to reduce CO2 emissions. |
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| Q: What
is the effect of enhanced CO2 on normal photosynthesis in the
ocean? - Bigelow Lab |
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Dr Richard Feely: Some
studies show that CO2 has a negative impact on some specific
species of phytoplankton, but only at extremely high levels
corresponding to pH levels of about 5.0. It is
not expected that that the ocean pH levels will get that low
from the release of fossil fuel CO2 emissions.
Dr Scott Doney: The main enzyme involved in carbon fixation
during photosynthesis is called Rubisco, and the overall rate
of photosynthesis could be limited by CO2 levels if not enough
CO2 was making it fast enough to the enzyme sites in the cell.
Laboratory experiments suggest that for most, but not all,
phytoplankton photosynthesis rates under present day CO2 levels
are saturated with respect to CO2; adding more CO2 does not
increase the rate.
Dr Carol Turley: Yes, it seems that CO2 will
have little direct impact on photosynthesis by phytoplankton.
However, the form or chemical speciation of nutrients that
phytoplankton use to grow may be affected by decreasing pH
(check out the Royal Society report for more info: http://www.royalsoc.ac.uk/document.asp?id=3249 )
and so this could impact phytoplankton species diversity. |
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| Q: If upwelling is intensifying in some
parts of the world. Does that mean that there will be outgassing
of CO2 as well? - Bigelow Lab |
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| Dr Richard Feely: Yes,
the recent paper by Feely et al (2006) in JGR indicates that
phase changes in the Pacific Decadal Oscillation can have an
impact on upwelling processes and, therefore, the release of
CO2 to the atmosphere. However, the changes are relatively
small when compared with the anthropogenic CO2 inputs into
the oceans. |
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| Q: Will increasing co2 levels impact
on ocean currents and create/effect events such as El Nino
and la Nina? - James D'Castro |
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| Dr Scott Doney: Increasing CO2 appears
to have already warmed the planet, which in turns alters atmosphere
and ocean circulation. Some model simulations suggest that
with climate warming, we will move into a world where the tropical
Pacific is in a persistent warm El Nino like state. There will
likely still be considerable year to year variability, though. |
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| Q: Is
iron and lime dumping in the ocean a solution to the acidification
problem? - Bigelow Lab |
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| Dr Carol Turley: Re
Iron/ lime dumping - couldn't do it on such a large scale to
make a difference Also adding lime would have big impacts on
the marine environment. |
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| Q: There are some in the US who are suggesting
that we use deep oceans to "sequester" CO2 from
large scale emitters (especially coal fired power plants).
We'd effectively be cutting our CO2 atmospheric emissions and
putting the CO2 directly in the deep ocean. Can someone comment
on the best scientific arguments on this subject? - Jonna Hamilton |
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| Dr Scott Doney: As Rich Matear notes below,
direct injection of CO2 into the deep-ocean accelerates a natural
process whereby much of the fossil fuel CO2 will eventually
end up in the ocean on thousand year time-scales. There will
be, undoubtedly, dramatic local impacts near an injection site;
some studies on acute exposure to very high CO2 levels have
been conducted, but not the longer effects of chronic exposure.
A more difficult issue is that even with injection down several
thousand meters into the ocean, some of that CO2 will leak
back to the atmosphere on timescales relevant to policy makers
(decades to a couple of hundred years). Because of that fact
and some logistical issues most sequestration efforts are currently
focused on geological sequestration (i.e., into used oil and
gas fields). |
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| Q: What about the sun
reflection sulphur plans ? How would the oceans and fish be
changed? - Cindy Snodgrass |
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| Dr Carol Turley: Sun
reflection, sulphur plans won't help with the ocean acidification
problem - they only help reflect some of the suns heat away
from the Earth's surface. |
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| Q: Is
there any possibility of acclimatization in calcifying organisms
to lower pH- physiological changes etc - Kim Davies |
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| Dr Richard Feely: There
is always this possibility. However, the limited number
of short duration experiments of Langdon and Atkinson (2006)
with corals at Biosphere 2 appear to indicate that this does
not happen. |
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| Q: If the deep sea is
undersaturated with respect to carbonate, how do you explain
the existence of deep sea calcifying organisms, such as vent
dwelling clams/mussels? - Kim Davies |
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Richard Matear: The
motivation for using the deep ocean to dispose of co2 is
the fact that most of our anthropogenic co2 emissions will
eventually reside in the ocean. Unfortunately, the process
is slow (several thousands of years). However, this deep
injection will at least have local biological impacts.
Dr Richard Feely: Some
calcifying organisms have an organic coating that protects
them while they are alive (i.e., clams, mussels). This organic
sheath tends to decay upon death and the shells tend to dissolve
shortly afterwards. |
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| Q: Would the effect of all of this in
ocean life ultimately affect life on land also? |
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| Dr Carol Turley: Apart
from 1 billion people depending on protein from the sea, ocean
themselves contribute to sustaining the planets life support
system, for example about 50% of global primary productivity
is carried out in the oceans and there are lots of important
feedbacks between the oceans and climate. |
