Ocean Acidification (Climate Bill Skirmishes Pt. 2) June 21, 2010

Fossil fuels threaten our oceans with dangers beyond just catastrophic oil spills.   Many people understand that carbon dioxide warms our atmosphere as a greenhouse gas.  It is much less publicized that carbon dioxide is also a critical pollutant in our oceans.

“We are entering a period in which the very ocean services upon which humanity depends are undergoing massive change and in some cases beginning to fail.”  -Ove Hoegh-Guldberg, director of the Global Change Institute at the University of Queensland in Australia.

Some people may be more familiar with ocean acidification than others, so I will start with the basics.

Because carbon dioxide is a gas, one might think that it resides predominantly in the atmosphere.  In actuality, about 93% of the world’s carbon dioxide is found in the ocean – 50x more than in the atmosphere.  In fact, the oceans are estimated to contain approximately 10x as much carbon as our remaining fossil fuel deposits. We don’t release it into the water, but it gets there nonetheless; like other gases, carbon dioxide can move easily from the air into the water.

When the atmospheric pressure of carbon dioxide is greater than the local pressure of carbon dioxide in surface water, molecular diffusion will transport the gas from the atmosphere into the water.  Therefore, as more carbon dioxide is added to the atmosphere (and the atmospheric pressure increases), more carbon dioxide ends up in our oceans.

Upon entering the water, CO2 undergoes some significant chemical reactions.

When carbon dioxide dissolves in the ocean, much of the gas reacts with water to form carbonic acid (H₂CO₃).  Carbonic acid is a weak acid that is not dangerous in and of itself – after all, we drink carbonated water and carbonic acid is actually formed in an intermediate step of human respiration.  However, if enough of it accumulates in the oceans, it can have severe indirect effects.

Carbon dioxide forms carbonic acid when dissolved in water.

On the 0-14 pH scale (in which lower numbers = higher acidity), ocean water has historically had a pH of about 8.16.  As a benchmark, “neutral” solutions like pure water and blood have a pH of 7, so our oceans are less acidic than pure water.

Since the Industrial Revolution, the oceans have absorbed almost half of the CO2 we have released into the atmosphere from fossil fuels and cement-manufacturing, and the pH has dropped by almost 0.1.  The pH scale is logarithmic, so each 1 point on the scale indicates an order of magnitude change; 0.1 may not sound like much, but it indicates about a 25% increase in ocean acidity so far.  It is estimated that the pH will drop another 0.4 by 2100.

That acidity would decrease the availability of the vital shell-building compound by 60% (explained below).  While the current pH levels are not record-breaking, the damage has already begun and the rapid rate of change is unprecedented and foreboding.  Ocean systems are remarkably sensitive to water acidity (which had remained relatively constant for millions of years), and marine biologists are very concerned that many species will not be able to evolve quickly enough to cope with this sudden, drastic change.

Ocean systems are remarkably sensitive to water acidity (which has remained relatively constant for the last , and marine biologists are very concerned that many species will not be able to evolve quickly enough to cope with this change.

Ocean acidification is occurring at an unprecedented rate. The scale of this graph is millions of years, that's why the last 2 data points and projections for the next century appear like a vertical line. Anywhere else in this record, 300 years would look like one overlapping, unchanged dot.

Sediment cores reveal that our oceans are acidifying at a rate not seen in 65 million years (since the dinosaurs roamed the Earth).  55 million years ago, virtually all shelled creatures in the ocean disappeared so quickly that geologists would consider it “overnight”.  Scientists attribute this die off to ocean acidification.  It took hundreds of thousands of years for shellfish to return to the oceans, and scientists estimate that we are now acidifying our oceans at a rate 10x faster than that which caused the last mass extinctions of shellfish.

How does ocean acidification affect marine life? Increasing acidity most directly affects aquatic organisms that form shells, such as corals, some algae, and the whole range of shellfish – as well as all the organisms and habitats that rely on those creatures.

Warning: chemistry content!
Shells are created out of calcium carbonate (CaCO₃).  Calcium carbonate structures can actually dissolve in water unless the surrounding water is saturated with carbonate ions (CO₃).  If the carbonate concentration of ocean water is too low, shells will be deformed.  It’s like osteoporosis for shellfish.  If the carbonate concentration drops enough, their shells will literally dissolve, and the animals will not be able to survive.

Shellfish require carbonate to build and maintain their shells. In acidic water, they can't get the materials they need.

If you’ve ever taken chemistry, you may recall that acidic solutions undergo “partial ionization” – acidic reactions are reversible and form an equilibrium between the intact acid and its separated ions.  That’s why acid formulae use that double arrow (as in the formula above).  When carbonic acid dissociates, it breaks down from (H₂CO₃) into:

1)    hydrogen ions (H), which cause acidity, and;

2)    carbonate ions (CO₃), upon which shellfish rely.

Carbonate ions can also bind with single hydrogen ions to form the bicarbonate ion (HCO₃), which cannot be used for shell construction.

The amount of carbonate available in water is determined by the pH of the water. In more acidic solutions (lower pHs), there are more free hydrogen ions to bind with carbonate to form bicarbonate – and therefore there is less carbonate available in the water.

This is what is happening to our ocean water.  As you now know, that is very bad news for shellfish.

As water becomes more acidic, there is less available carbonate (CO3) for shellfish to use. This is happening today. The black line compared to pH is the one we care about.

A 2005 study examined the impacts of ocean acidification:

“Sea creatures such as corals, shell fish, sea urchins and star fish are likely to suffer the most because higher levels of acidity makes it difficult for them to form and maintain their hard calcium carbonate skeletons and shells. For example, even under the ‘low’ predictions for future carbon dioxide emissions into the atmosphere, the combined effects of climate change and ocean acidification mean that corals could be rare on tropical and subtropical reefs, such as the Great Barrier Reef, by 2050. This will have major ramifications for hundreds of thousands of other species that dwell in the reefs as well as for the people that depend upon them, both for food and to help to protect coastal areas from, for example, tsunamis.”

The “tipping point” for reefs, ensuring reef erosion and even eventual extinction, could come as soon as 2050.

Mind you, this will be a separate, additional stressor on vital coral reefs (albeit with the same cause) as coral bleaching in warming waters.

Ocean acidification presents a clear threat and a compelling economic argument, even independent from climate change.  U.S. commercial fishing brought in $4 billion in 2006.  Coastal tourism just in the Florida Keys, which is driven by coral reefs, contributes $1 billion to the economy every year.  These are all jeopardized by ocean acidification.

So, in December of last year, Rep. Jay Inslee (D-WA) and Rep. Ed Markey (D-MA) introduced House Resolution 989:

“Expressing the sense of the House of Representatives that the United States should adopt national policies to prevent ocean acidification, to study the impacts of ocean acidification, and to address the effects of ocean acidification on marine ecosystems and coastal economies.”

Simple enough, right?  It finally came up for a vote this month.

Rep. Jason Chaffetz (R-UT), who clearly has a lot at stake in regard to our nation’s oceans, voiced his objections: Why, he asked, do we need this resolution if Congress allocated $76 million to researching and monitoring ocean acidification as part of the Omnibus Public Land Management Act of 2009?

Because, as Rep. Inslee explained, merely monitoring is not enough.  A threat we see coming will materialize whether we watch it arrive or not. We need to act.

Now, H. Res. 989 was never going to be that action we need.  Such nonbinding resolutions are largely inconsequential.  If passed, H. Res. 989 would have done nothing but publically acknowledge that this is a problem we need to address and possibly raise some needed public awareness.  But it’s difficult to rationally oppose such a motion because it has literally no drawbacks.

Mr. Chaffetz finally arrived at the crux of the conservatives’ concern:

“It talks in the very first sentence, ‘Expressing the sense of the House of Representatives that the United States should adopt national policies.’ By ‘national policies’ does the gentleman mean the cap-and-trade?”

I could relay to you the rest of the congressional debate about this resolution, but I don’t think I have to.  Earlier this month, 241 representatives voted for the resolution, including 19 Republicans and those from the vast majority our nation’s oceanic coastline.  However, such resolutions require the support of 2/3 of the House to pass.

A minority of conservative representatives (including 20 Democrats) defeated H. Res. 989 – about ocean acidification – because they didn’t want to be bound to a non-binding resolution that could potentially be interpreted to offer written encouragement for a cap-and-trade solution to our global warming emissions.  Partisan politics at its finest.

I wrote last week about one of the first skirmishes in this year’s congressional climate battle: the Murkowski Dirty Air Amendment.  This debacle was another.

Like climate change, ocean acidification poses a threat that we must essentially address now or never.  In blocking urgent energy reform, irresponsible congressional conservatives are imposing unprecedented costs and burdens upon younger generations.  As a member of one of those younger generations, I would very much like to take this opportunity to tell those conservatives what they can go do to themselves.  …But I’ll restrain myself for now.

Just for the record, ocean acidification and climate change have more in common than just the same cause: ocean acidification is actually one of the amplifying positive feedback loop that will accelerate climate change if we do not stop it now.

If you’re interested in learning more about Ocean Acidification, check out this great video by the Natural Resources Defense Council: