I'm going to have to re-read Tracers in the Sea, but if the 5% carbon flux from surface to depth could be increased to 20-25% (I have no idea how to accomplish that), iron fertilization would be a significantly more viable idea. The problem with ocean acidification is the direct absorption of increasing CO2 from the atmosphere into surface waters. If instead the CO2 is converted to organic carbon and then sinks to depth where its remineralized (mostly on the bottom), then this is a MUCH bigger volume to affect [compared to the surface lens] and a much slower process, too. I have to re-read TriTS (note the chemical oceanography joke) to remember if organic matter remineralization raises or lowers pH. Probably lowers it -- respiration releases CO2, of course. But I think that lowering the pH of the huge volume of abyssal water a little would require a lot of fecal pellets.

I'm just wondering if the land based carbon sequestration ideas have similar problems. I'm guessing that lowering pH in the ground wouldn't be as potentially devastating.All in all, I'm with you and dubious about the success of such programs.

A few sessions at next February's AAAS Meeting that touch on this . . .

Session Type:

90-Minute Symposium
Number:

090-141
Title:

The Other Carbon Dioxide Problem: Ocean Acidification
Track:

Climate Change and the Environment
Session Start/End Time:

Friday, Feb 15, 2008, 8:30 AM -10:00 AM
Synopsis:

Ocean acidification is a global problem ridden with global policy issues of monumental proportions. Ocean chemistry changes will affect protein availability, ancient cultures, and other societal foundations. Ocean acidification is only just emerging on the public radar screen, as land and atmospheric issues dominate the dialogue. The public must understand the implications of changes in the oceans already underway that could affect their lives deeply. The panel presents coherent messages about changes underway in the world’s oceans from elevated carbon dioxide levels and the associated climate change and ocean acidification effects. Discussants provoke and provide counterpoint. To date, climate change dialogue about the oceans has focused on sea level rise. The growing change in ocean pH has been absent from discussions and urgently needs to be raised. As ocean waters continue to absorb carbon dioxide, their capacity to do so declines and will result in more carbon dioxide remaining in the atmosphere. As carbon dioxide saturation of the oceans travels deeper, where marine life is less adaptable, scenarios loom large of potential collapses of species of great importance, from corals to pelagics, from plankton to mammals. Because such rapid changes have not occurred in 20 million years, scientists must seek new answers to questions not asked before. This calls for increased interdisciplinary research and collaboration, efficient information transfers and exchanges, and public understanding.
Organized by:

Judith T. Kildow, Monterey Bay Aquarium Research Institute, Moss Landing, CA
Presentations:


Moderator--Judith Kildow, Monterey Bay Aquarium Research Institute, Moss Landing, CA

Environmental Perturbation and Biological Responses in Earth History--Andrew H. Knoll, Harvard University, Cambridge, MA

Designing Experiments To Predict the Impact of Rapidly Changing Ocean Chemistry--Peter Brewer, Monterey Bay Aquarium Research Institute, Moss Landing, CA

Marine Biota Sensitivities to Ocean Acidification: Risks and Uncertainties--Ulf Riebesell, Leibniz Institute of Marine Sciences, Kiel, Germany

Discussant--James Barry, Monterey Bay Aquarium Research Institute, Moss Landing, CA

Discussant--Carl Safina, Blue Ocean Institute, East Norwich, NY

*****

Session Type:

180-Minute Symposium
Number:

180-005
Title:

Strange Days on Planet Ocean: New Insights on the Effects of Climate Change
Track:

Climate Change and the Environment
Session Start/End Time:

Sunday, Feb 17, 2008, 1:45 PM - 4:45 PM
Synopsis:

Although much attention is focused on the effects of global climate change on land, among the major ramifications are significant changes to the oceans. Covering 71 percent of the Earth’s surface, and acting as a temperature regulator, oceans are intimately linked with global climate. Climate changes also affect ocean currents and circulation, temperature, pH, carbon sequestration, productivity, and the distribution and abundance of marine life. As the Earth’s temperature heats up, what are the global trends in the ocean? How are these global changes manifested in the functioning of ecosystems? What are the expected feedbacks to climate regulation and biological communities? Are key organisms able to adapt? What are the management implications? This symposium connects leading researchers in some of these diverse fields: remote sensing, biogeochemistry, oceanography, ecological physiology, biodiversity, and climate change policy. Within this symposium, researchers present synthetic views of the current state of the science and provide specific examples on both global and regional scales.
Organized by:

Elizabeth H. Riley, Partnership for Interdisciplinary Studies of Coastal Oceans, Corvallis, OR;Kristen Milligan, Partnership for Interdisciplinary Studies of Coastal Oceans, Corvallis, OR
Presentations:


Moderator--Jane Lubchenco, Oregon State University, Corvallis, OR

Surface Ocean Acidification and Carbon Cycling--Scott Doney, Woods Hole Oceanographic Institution, Woods Hole, MA

Biological Consequences of Ocean Acidification for Larval Marine Invertebrates--Gretchen Hofmann, University of California, Santa Barbara, CA

The Coral-Carbon Connection: Impacts of Greenhouse Gases on Coral Reefs--Nancy Knowlton, National Museum of Natural History, Washington, DC

Ocean Productivity and Climate Driven Changes--Michael Behrenfeld, Oregon State University, Corvallis, OR

A Slowing Oceanic Conveyor Circulation? How Can Observations Inform Decision-Making?--Klaus Keller, Pennsylvania State University, University Park, PA

Changes in Coastal Upwelling Ecosystems Around the World--Jack Barth, Oregon State University, Corvallis, OR

Discussant--Jane Lubchenco, Oregon State University, Corvalis, OR

Next year's AAAS meeting will be excellent. The Science Communication panel on February 17 happens at the same time as Climate Change and the Environment.

So many sessions, so little time...

There's also going to be an ocean acidification session at this year's ASLO/AGU meeting in Florida in March.

I've been looking, from an amateur perspective, at a couple of GeoEngineering options that might address the CO2 level, and one of them might also address either acidification, or the reduced supersaturation of calcium carbonate that it causes, and that is probably the reason for reduced calcification.

According to Ridgwell and Edwards 2007, the dissolving of CaCO3 (calcium carbonate) by cold bottom water is part of the process of adapting to increased atmospheric CO2:

"Each mole of CaCO3 that dissolves
removes one mole of CO2(aq) to form two
moles of bicarbonate:

CaCO3 + CO2(aq) + H2O → Ca++ + 2ΗCO3-
(the difference between dotted and dashed
HCO3− inventory trajectories in Fig. 6.8c).
Thus, water masses that have passed over
carbonate-rich sediments become, in a
sense, ‘recharged’, and are able to absorb
more CO2 from the atmosphere (Fig. 6.7a)."

If we distribute finely powdered limestone in the sub-polar waters, as it dissolves it will help the oceans absorb more CO2. These waters (AFAIK) are undersaturated in CaCO3, so few if any organisms produce limestone shells.

The time-frame for the natural process is measured in 10's of thousands of years (Ridgwell and Edwards 2007), but potentially it could be sped up by many orders of magnitude by human action. I'm not sure of the chemistry of this, much less the potential impact on biota, but if no show-stoppers are immediately apparent, perhaps it should be investigated.

The second option works on an even longer time-frame:

"The reaction involved in the weathering
of calcium silicate minerals (particularly
the feldspar family, which are the most
abundant group of minerals in continental
rocks) can be written as:

2CO2 + 3H2O + CaAl2Si2O8 → Ca++ + 2HCO3– + A12Si2O5(OH)4

This differs from the weathering of carbonate
rocks (in contrast to the weathering
reaction listed in Section 6.2.2) in one fundamental
regard; it takes two moles of CO2
to weather each mole of CaAl2Si2O8 and
release a single mole of calcium ions (plus
2 of bicarbonate ions). The calcium ion is
subsequently removed from solution in the
same precipitation reaction as before, meaning
that only one mole of CO2 is released
back to the ocean (and atmosphere). The
weathering of silicate rocks is thus a net sink
for atmospheric CO2 (Berner, 1992) (Fig.
6.7c) – i.e. one mole of CO2 is being sequestered
for each mole of calcium silicate mineral
weathered." (Ridgwell and Edwards 2007)

My proposal is to distribute finely powdered (artificially eroded) basalt into the warmer tropical ocean waters, emulating this reaction but on a much faster time-scale. I'm not sure whether the dissolution of calcium (and magnesium) oxides would raise the pH, but I'm fairly sure it would raise the supersaturation level of CaCO3, which ought to help out the coral, etc.

Again, if there are no apparent show-stoppers (I'm not enough of a chemist to know for sure), perhaps it ought to be tried in the lab or on a small scale in the tropical oceans.

Reference

Ridgwell and Edwards 2007: Geological Carbon Sinks by Andy Ridgwell and Ursula Edwards, chapter 6 of Greenhouse Gas Sinks edited by D Reay, N Hewitt, J Grace, and K A Smith http://www.ggy.bris.ac.uk/personal/AndyRidgwell/pubs/Ridgwell_and_Edwards_2007.pdf

This latest blog article puts Elliot's recent contribution on your earlier one into greater perspective. It's worth reposting on this thread:

http://dotearth.blogs.nytimes.com/2007/11/06/project-to-harness-plankton-puts-to-sea/index.html?ex=1352091600&en=e47c2c4ccbc45d81&ei=5089&partner=rssyahoo&emc=rss

I just learned aboutOcean Acidification and the situation is really terrifying. Why haven't we been hearing more about it in the media. It's certainly a much more serious threat than Bird Flu or whatever we're supposed to be afraid of this year.

In response to Ak above, on buffering the ocean by enhancing CaCO3 dissolution: unfortunately that just wouldn't work well. The rate of dissolution is too slow and the rate of oceanic mixing is too slow so we'd still have the same problems most places. If we were going to the effort of actually rapidly dissolving CaCO3 in many, many locales we'd find that we are actually putting a heck of a lot of resources into solving a problem when it would be easier and much more cost effective to simply stop emitting CO2.

p.s. The article in Science from Dec. 13 about the response of coral reefs to rising CO2 is worth a read. At 500 uatm and higher of CO2, which we are likely to pass this century, almost all coral reefs will be sufficiently stressed due to increased temperature (coral mortality due to bleaching and disease) and ocean acidification (reduced rates of calcification) that they will be in an inevitable state of decline. This is far from the last word on the topic, but is a very legitimate prediction. I'll mention my MS thesis is looking at the effects of ocean acidification on coral calcification...hopefully this indicates I'm not just some crackpot.

Chris...

It would not be "easier and much more cost effective to simply stop emitting CO2." The simple fact is that converting our 10-20 terawatt power requirement to some carbon-free source will be incredibly difficult, and meet extreme resistance from organizations locked into fossil fuel combustion. Reducing that power requirement will be even harder, IMO out of the question.

I know that lots of scientists with little understanding of the eco-political situation don't understand how difficult this process will be, just as many people involved in economic and political processes don't understand the science of CO2, but that doesn't change the realities.

Just bringing the GROWTH of CO2 emission to a halt will be a considerable effort, and realistically won't happen before 2050. If things go as they do today, the amount of CO2 in the atmosphere (with its associated effects) by that time will be so far advanced that natural processes would take centuries to recover pre-industrial levels.

In many ways, the building of a new remediation system would be cheaper and easier than trying to stop CO2 emissions on such a short time-frame, just because it's new. That's not to say the CaCO3 idea is the one, it turns out there is a show-stopper: surface water is supersaturated with respect to all natural forms of CaCO3.

The easiest way, IMO, to reduce atmospheric CO2 is to create very large artificial sinks. My current favorite is large artificial peat bogs, with the resulting material wrapped in concrete and dumped in one of the deep ocean trenches, ideally the Peru-Chile trench.

Of course, we should also repair the natural sinks that have been destroyed over the last few centuries.

But that is merely a different take on what I'm suggesting. The only thing that will work and is remotely practical is reducing CO2 emissions to the atmosphere. Whether we are using alternative energy sources or artifically sequestering CO2 from fossil fuels (and not dumping the CO2 in the ocean--that has been suggested, but I think most people now realize what a terrible idea it is) the impact on the atmosphere and on oceanic chemistry is the same. As long as the CO2 isn't going into the atmosphere and hence into the ocean, the effect is the same, however we achieve that end.

I will mention, as a side note, that solar panels with a production cost of $0.30 per watt, similar to the cost of using coal, have recently become available. There are a lot of promising avenues that can help get us off of fossil fuels completely in the next few decades.

very helpful information. thank you.