Osteoporosis of the Sea

As fat droplets of water fell into my outstretched hands in one of Florida’s spectacular winter rainstorms, I closed my eyes remembering a certain train concierge. I still recall his face; his staunch dedication to the position that global warming was a hoax. Also though, I remember how his eyes softened during our conversation when he realized I was simply trying to understand him and not lecture him.

Last year, I wrote about our encounter in the piece “Having the Conversations You Don’t Learn in School.” Since that time, I have thought of alternate ways to have this conversation. If one of our end goals is to have individuals and societies with the smallest carbon footprints possible, then maybe the battle is not to convince everyone that global warming is real. Perhaps we could spend more of our energies brainstorming the inarguable reasons to reduce overall carbon emissions and the best ways to communicate them.

(Source: IPCC, 2007b)

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The Argument:

The case can be made that ocean acidification has the potential to bypass, to an extent, the debate about global warming, while driving home the need to mitigate carbon emissions. The EPA has stated, “It is important to note that ocean acidification is not a result of climate change, but is rather a direct consequence of the increased CO₂ levels… (E.P.A., 2011).”
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Osteoporosis of the Sea?

Just as we make our bones out of calcium and phosphate, corals make their exoskeletons out of calcium carbonate. In the ocean, losses in carbonate ion concentration are cause for concern, just as people become concerned when they are calcium-deficient. About a decade ago, researchers discovered that the carbonate ion concentration is decreasing, making it more difficult for existing and new corals to grow. 

• The Facts -
  

1. Since pre-industrial times, the ocean has and will continue become more acidic due to increasing CO₂ emissions (IPCC, 2007b).
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2. Ocean pH is projected to decline 0.5 units by 2100 if current trends in rising CO₂ emissions continue (E.P.A., 2011).
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3. Increasing ocean acidification will negatively impact coral reefs and other marine calcifers, ultimately affecting fisheries humans rely on (Fabricius et al, 2011).

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The Chemistry of Ocean Acidification (OA):

• OA is… a term used to describe dropping pH levels in the ocean.
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• Quick pH review… pH measures the hydrogen ion concentration of a solution to determine its acidity or basicity on a scale of 0 to 14. Acids have lower pH values (due to high hydrogen ion concentrations), while bases have high pH values (due to low hydrogen ion concentrations).
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• Extent of the ocean’s pH drop? Studies have shown that since the beginning of the Industrial Revolution, overall ocean pH has decreased from 8.25 to 8.14 (Jacobson, 2005). ….. This may seem like a minute change, but this alteration in global ocean chemistry reflects a 30% increase in hydrogen ion concentration (remember, more hydrogen ions –> a lower pH –> a more acidic state). This is the biggest change to ocean pH in the last 20 million years!
  

• What’s the connection between decreased ocean pH and carbonate availability?
  

  (Source: http://oceanclimate.org/resources/6)

  Carbonic acid (H₂CO₃), the same ingredient that makes soft drinks fizz, is produced when atmospheric CO₂ combines with sea water. Carbonic acid then releases hydrogen (H⁺) ions into the ocean, lowering the pH, and forming bicarbonate (HCO₃^-) and carbonate (CO₃^2-).
  
  The excess hydrogen ions in the water bind with carbonate, keeping it mostly in its bicarbonate form; a form that corals and other marine calcifers cannot utilize to to build their own “skeletons.” Similar to how our bones appear during osteoporosis, the exoskeletons of corals and calcifying marine organisms become thin, brittle and transparent – potentially even dissolving.

  In summary… High CO₂ levels = low ocean pH (more acidic) = less carbonate = coral reefs threatened (Read more on OA chemistry).

   

Fishery and Biodiversity Threats:

As carbonic acid chemically alters calcium carbonate to the point where marine calcifers can no longer use it, the shifts occurring in ocean pH threaten the very foundation of the food chain for the planet’s fisheries. From delicately-shelled zooplankton to clams, mussels, crabs, oysters and even coral reefs, ocean acidification has the potential to disrupt shell formation in many species.

Studies have shown that in areas with underwater volcanic seeps emitting naturally high levels of CO₂, coral reefs communities are considerably less diverse. One such site in Papua New Guinea predicts that at the end of the century with the projected pH declines, these Indo-Pacific corals will experience a 39% decrease in biodiversity (Fabricius et al., 2011).

Corals reefs form specialized habitats that provide shelter, food and breeding sites for niche communities of marine species, mainly economically important marine fish. Ocean acidification poses a serious threat to recreational and commercial fisheries, as well as global food security.

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Compounded Pressures:

The ocean and coral reefs face both global and local threats, both of which must be addressed for successful marine conservation. It may be tempting to focus all conservation efforts on the most imminent threats, such as pollution, overfishing and habitat destruction. But losing sight of more distant threats, such as ocean acidification, we run the risk of losing corals sooner due to combined pressures.

If we think in terms of human health, imagine your doctor tells you that an artery to you heart is partially blocked and in addition, you have a slowly metastasizing cancer. If you do nothing, you’ll die from a heart attack in 4 months or from the cancer in 2 years. What do you do? Will you choose to ignore the cancer but eat healthier and exercise to cure the heart disease? Or do you choose to treat the cancer and ignore the immediate threat of a heart attack? Neither! You’d choose to tackle both the short and long-term issues that threaten to kill you. It’s the same concept for coral reef and marine conservation in general – best to work simultaneously on immediate and future threats.
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The Path Forward:

• What’s the cause of OA? Increased CO₂ levels in the atmosphere!
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• What’s predicted? Unless we swiftly reduce our CO₂ emissions, scientists warn that ocean acidification with worsen, with another .3 -. 4 decrease on the pH scale by the year 2100 (IPCC, 2007b). Without action to minimize atmospheric CO₂ levels, the Earth’s ocean may experience an acid spike more intense than has occurred in the past 8,000,000 years (Greene, 2005).

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Linking rising CO₂ in the atmosphere with a lowering of ocean pH (ocean acidification) could be a means of garnering support for reductions in CO₂ emissions from some climate change skeptics. Clearly, the argument is still based on the need to re-connect people with the sea, highlighting the importance of the ocean and the benefits it provides to every human.

The situation may be dire and the increases in atmospheric CO₂ seemingly unstoppable, but we have within our powers, the ability to turn this negative trajectory around. Climate change scientist and ocean acidification expert Dr. Charlie Veron has said, “It’s no use saying by 2030 that we’ll do this or we’ll do that, by 2030 it will all be too late. That is the problem. So we have to change. And humans are, I believe, very good at change.”

As a species, we survive by evolving; by adapting; by innovating new and better ways of living. It is up to us to find the solutions to our environmentally damaging practices today, because if we leave them for future generations to remedy, there may not be anything left to fix.

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Action Resources:

Uncover ways to halt OA & invest in a clean energy future

Calculate, offset & reduce your carbon footprint

Rethink, Recycle, Reward – Earn points for green actions

About the Author Christine Beggs is the founder of Project Blue Hope, a site dedicated to spreading her wish for a “Future of Blue.” Currently pursuing her Master’s degree in Marine Conservation, Christine is passionate about communicating ocean sciences. Christine’s Posts →

 
References:

ABC. “Ocean Acidification – The Big Global Warming Story.” Catalyst. 8 Jan 2011. <http://www.abc.net.au/catalyst/stories/s2029333.htm>.

E.P.A. “Future Ocean Acidification.” Climate Change – Science. 3 Jan 2011. <http://www.epa.gov/climatechange/science/futureoa.html>.

Fabricius K. E., et al. 2011. Losers and winners in coral reefs acclimatized to elevated carbon dioxide concentrations. Nature Climate change 1:165-169.

Gattuso J.-P., et al. 2011. Ocean acidification: knowns, unknowns and perspectives. In: Gattuso J.-P. & Hansson L. (Eds.), Ocean acidification, pp. 291-311. Oxford: Oxford University Press.

Greene, David. 2005. “The Acid Ocean – the Other Problem with CO₂ Emission.” RealClimate. 11 Jan 2011. <http://www.realclimate.org/index.php/archives/2005/07/the-acid-ocean-the-other-problem-with-cosub2sub-emission/>.

Hall-Spencer J. M., et al. 2008. Volcanic carbon dioxide vents show ecosystem effects of ocean acidification. Nature 454:96-99.

IPCC, 2007b: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning (eds.)].

Jacobson, M.Z. 2005. Studying ocean acidification with conservative, stable numerical schemes for nonequilibrium air-ocean exchange and ocean equilibrium chemistry. Journal of Geophysical Research – Atmospheres 110: D07302.