Demystifying Ocean Acidification: a Human Interest Story

By Neyssa Hays

When fifteen-year-old Christopher Sabine’s parents sold the family home in Mobile, Alabama, bought a sailboat, and set out for a year of sailing the oceans, they were setting their young son on his life’s path (Sabine 2012).  On the beautiful waters of the Bahamas, he met a girl and developed enough of a crush to determine the only university to which he would apply: Texas A & M.  The fates were smiling on him and, fortunately, he was accepted.  He found the girl again, too, but on their first date, they discovered they weren’t compatible (he did, however, eventually find his future wife there).  More importantly, during the year of sailing with his parents, he fell in love with the ocean, determined then that he would be an oceanographer, and hasn’t wavered since.

Dr. Christopher Sabine at work on a NOAA science vessel (NOAA 2010)

Dr. Christopher Sabine at work on a NOAA science vessel (NOAA 2010)

The only change of plan was the direction of his oceanography career; originally, he planned to study physical oceanography but about the same time he was realizing physics involves more math than he was comfortable with, he won an award for his academic work in chemical oceanography.  Further solidifying this choice was a summer he spent in a course at the Bermuda Biological Station with geochemist Dr. Fred Mackenzie from the University of Hawaii (UH).  Again applying for only one graduate school, Sabine was accepted to UH and Dr. Mackenzie became his advisor.  Sabine said he “had a vision in mind” (Sabine 2012): to achieve a PhD in oceanography by the time he was 25.  Ultimately, he missed his deadline, but only by a few months.

A slender man with a welcoming smile, warm demeanor, and cheery chuckle, as an oceanographer for NOAA (and as of last November, the most recent director of NOAA’s Pacific Marine Environmental Laboratory (PMEL) in Seattle, Washington) Dr. Christopher Sabine studies some of the most depressing statistics of our times: CO2 emissions and their effects on our oceans.  Surprisingly, he is also one of the most jovial people I’ve ever met.

Sabine (background) and longtime research partner, Richard Feely (Levin 2007)

Sabine (background) and longtime research partner, Richard Feely (Levin 2007)

Apparently he’s too cheerful for some people.  According to Sabine, a few years ago his long-time research partner, Dr. Richard Feely (also of NOAA’s PMEL in Seattle), and he were filmed for a documentary called “A Sea Change” (Huseby 2009).  When the film was screened for a test audience the feedback was that, “I smile too much,” said Sabine.  The audience didn’t approve of someone smiling as he reported statistics of doom and gloom.  But, Sabine says it’s just in his personality to be an optimist.

“I’m amazed by human ingenuity and our ability to respond to what seem to be hopeless causes, and I’m convinced that we’ll figure a way out of this. And I hope that in some way, I’ll be a part of it,” he told me (Sabine 2012).


The “this” he’s speaking of is the ever-rising acidity levels of our ocean waters, ocean acidification, to use a term coined by the Royal Society shortly after Sabine and Feely published two breakthrough papers about it in the July, 2004 issue of Science (Sabine 2012). Working in a very similar field from different angles, Sabine and Feely complement each other in figuring out what’s going on with the oceans.  Said Sabine, “I focused on how it was happening while Dick focused on the effects of it on marine organisms” (Sabine 2012).

The cover of Science, July, 2004 showing the pteropod Clio pyramidata (Gilmer and Harbison 2004)

The cover of Science, July, 2004 showing the pteropod Clio pyramidata (Gilmer and Harbison 2004)

The titles of their articles clearly illustrate this division; Sabine’s article is entitled “The Oceanic Sink for Anthropogenic CO2” where Feely’s is “Impact of Anthropogenic CO2 on the CaCO3 System in the Oceans.”    Sabine analyzed results of tests showing rising acidity levels in the oceans while Feely theorized that with the rising acidity levels, animals such as the thinly shelled pteropods Clio pyramidata (shown left) and Limacina Helicina (shown below), as well as corals, clams, mussels and other creatures that make their shells from calcium carbonate will find it more difficult to survive (Feely et al. 2004).

The    Pteropod Limacina Helicina (NOAA 2010)

The Pteropod Limacina Helicina
(NOAA 2010)

Pteropods are commonly called sea butterflies, and at roughly the size of a small pea are some of the most important food resources for a variety of ocean dwellers including the economically important salmon and several species of whale (NOAA 2010).

Nature generally insists on balance.  Land, air, and water have always exchanged gases in a carefully balanced cycle regulated by seasonal changes, geomorphic pressures, and biological systems that scientists are still working to fully understand (Sabine and Feely 2007).  As a natural part of that cycle, carbon dioxide is taken up and released by a host of sources, including animals, living and decaying plants, the oceans, and even the breakdown of certain rocks.  Whether one is taking it up or releasing it depends in part on where the concentrations are.  If the concentrations are higher in one part of the triad, pressure is placed on the other two to take up the excess and bring everything back in balance.  As humans have dramatically increased the concentrations of CO2 in the atmosphere through the burning of fossil fuels, the pressure on the oceans and land to take up that CO2 has increased, and through a process similar to osmosis combined with its churning and seasonal mixing, the oceans have responded.  Initially, scientists heralded this response as our saving grace, but as atmospheric CO2 continued to rise, scientists like Sabine, Feely, and others around the world began to wonder how it was affecting the oceans themselves.

According to Sabine, atmospheric levels of CO2 are over thirty percent higher than they were 200 years ago, and half of that has appeared in the last 30 years (Sabine, 2011).   However, it doesn’t stay in the atmosphere; the oceans currently take up between one-third and one-fourth of the anthropogenic (human created) CO2 in a reversal of their pre-industrial roles.  Before the industrial revolution, the oceans were an atmospheric source of CO2 as biophysical processes such as decay of organic materials released the gas into the water, which then released it in the atmosphere (Sabine and Feely 2007).  But, as carbon dioxide levels in the atmosphere have increased exponentially, the exchange has reversed. And as they buffer us from some of the effects of our modern lifestyles, they are becoming more and more acidified.

(NOAA 2010)

(NOAA 2010)

The oceans are a complex mixture of water and dissolved ions, each playing a unique and important role.  Some of those ions include calcium (Ca) and carbonate (CO3), the basic building blocks used by sea creatures such as clams, corals, snails, and pteropods to form calcium carbonate into unique, elaborate, and beautiful armored homes.  According to Sabine, “In shallow waters you typically get the reaction CO2 + H2O + CO3 = 2 HCO3” (bicarbonate ions), a weak acid (Sabine email 2012).  “The more CO2 you add, the more you use up CO3 so the more difficult it is for organisms to find a dissolved CO3 and a Ca to form their shell. Eventually, if you continue to add CO2, you will begin to dissolve the shells or at least make the depth that shells naturally dissolve shallower.” While currently there is enough CO3 in the shallow waters to keep this from happening, tests have shown (see image below) that at current rates of acidification some ocean waters will grow corrosive enough by the end of this century to do just that (NOAA 2010).

Pteropod shell left in sea water of pH and carbon balances equal to projections for the year 2100 (NOAA 2010).

Pteropod shell left in sea water of pH and carbon balances equal to projections for the year 2100 (NOAA 2010).

Scientists estimate that the oceans have the capacity to take up 70 to 85 percent of the anthropogenic carbon dioxide released into the atmosphere, but because of the slow process of mixing it could take thousands of years to do so (Sabine and Feely 2007).   Thus far, the vast majority of that carbon dioxide is staying in fairly shallow waters (less than a quarter mile in depth); most deep ocean waters have not experienced elevated levels of CO2.  Absorbing carbon at a rate of roughly two and a half petagrams per year, the oceans are not able to remove the carbon as quickly as it is accumulating in the atmosphere (Sabine et al. 2004).


One petagram is one billion metric tons.  That’s a ridiculously large number to try to grasp, so Sabine has done some searching to find the right analogy to draw a picture.

“At first,” he said, “I tried a VW bug analogy …” because a VW bug weighs about one metric ton.  So, we’re putting three billion VW bugs in the ocean per year?  But that wasn’t working for people either; they couldn’t equate the form of a car with carbon.  Then one day, Sabine was talking about it with a NOAA project manager who said, “Coal is mostly carbon, isn’t it?  How many coal cars would it fill?”  So Sabine crunched the numbers and had his analogy.

Coal train in Wyoming. (Goebel 2006)

Coal train in Wyoming. (Goebel 2006)

Coupler to coupler, a U.S. hopper car is sixty feet long and carries 100 U.S. tons of coal; a train carrying one petagram of coal would need to be about 156,500 miles long.  At the equator, the earth is approximately 24,902 miles around.  That equates to a train full of coal wrapping around the equator over six times for one petagram of carbon, and we’re pumping about  nine petagrams of carbon a year into our atmosphere.  That’s the equivalent of 54 trainloads of coal around the earth every year, a third of which is going into the ocean.


Of course, ocean acidification is not something that humans can detect with a trip to the beach.  It’s taken teams of researchers years to develop the technology necessary to let them analyze the subtle changes in the oceans, and countless hours of running what Sabine described as a grid pattern of ship cruises wherein they stop every 30 miles to take water samples from the surface to the bottom.  As they travel, the scientists analyze the samples they’ve taken.

In his new position as director of NOAA’s PMEL in Seattle, Sabine said he won’t get as much time on the water, so he’s “keeping some of the [other] fun parts” to himself, his favorite being technology development. The technology he’s very excited about is something called a Liquid Robotics “Wave Glider,” an ocean going vessel fitted with CO2 sensors he developed with Chris Meinig, PMEL’s lead engineer  (Ahearn, 2011).

Wave Glider (Feely 2011)

Wave Glider (Feely 2011)

Once it’s deployed from a small fishing boat anywhere in the world, Sabine and his team control the wave-propelled craft via satellite communication from their laboratory in Seattle.  “If I see an interesting feature I can say, ‘Turn around, go back and look at that again.’ Or if I want to go to a particular spot I just point it in that direction and off it goes,” Sabine said.

A bit smaller than seven feet long, the glider’s dimensions were set by the need to ship it anywhere in the world as most commercial carriers can only accept shipments no larger than seven feet (Sabine 2012). The rest of the design,including the PMEL-designed CO2 sensors, Liquid Robotics-designed wave-riding fins, and solar-energy panels were from imagination and engineering know-how.


Sabine’s cruises have not always gone as planned.  In 2008 Sabine was the chief scientist on a 274-foot NOAA “top of the world class ocean vessel” near South Georgia Island (east of Patagonia in the Atlantic sector of the Southern Ocean).  As the chief scientist, he was responsible for all of the other scientists and equipment on board.  Their mission for that cruise: analyze how “CO2 moves between air and water during high wind and rough sea conditions” (Sabine 2012). In other words, their plan was to face a major storm head-on and measure the chemical changes it caused in the water as it was raging.  Laboratory studies had shown that gas exchange between air and water is very high during high-wind conditions but this had never been tested in the “natural environment.”

NOAA Research Ship Oscar Dyson (NOAA)

NOAA Research Ship Oscar Dyson (NOAA)

“We could see [the storm] coming on the weather radar,” Sabine told me.  “Yes, alright!  Perfect conditions!” they thought. But as the storm moved closer and the waves rose higher, the ship’s engines started having problems.  With “an array of measuring equipment” trailing in the water behind them and an Antarctic sea storm nearly on top of them, the ship “suddenly went dead in the water.”  They couldn’t go anywhere, and they certainly couldn’t take the measurements they’d gone out to retrieve.  Fortunately, the ship’s crewmembers were able to get enough power going to “run away” from the storm and hide behind the island until it had passed and they were able to go back and collect some data in somewhat calmer conditions.


Sabine’s “Employee of the Month” Photo (NOAA 2007)

Sabine’s “Employee of the Month” Photo (NOAA 2007)


Though Sabine has won many awards for his work, including NOAA’s Outstanding Scientific Paper Award multiple times and Seattle’s Federal Executive Board’s Public Service Award (Goldman 2011), he is most proud of the recognition he’s received as part of a team.  In 2006 he and his team were awarded the Department of Commerce Gold Medal for their work on ocean acidification, and when in 2007 the Intergovernmental Panel on Climate Change was awarded the Nobel Peace Prize, they recognized Sabine as a major contributor.  He said there are no Nobel prizes in his future, but as director he will take pride in watching other members of his team win awards.

Sabine said he hopes his work will make a difference.  His primary focus is on “educating people and trying to impress upon them the importance of changes in our global oceans, knowing that if we really set our mind to it we can get ourselves out of this downward spiral that we’re in when it comes to the oceans, CO2 emissions, and climate change.”

In a time when nearly every environmental prediction we hear is that we’ve doomed ourselves to an inevitable, accelerated demise, forecasts like Sabine’s give hope that if we choose to make the simple, necessary changes, we can regain control of our train, our environmental destiny, and avoid a disastrous derailment.


Ahearn, Ashley. 2011. The Five Coolest Things About Ocean-Exploring Robots.  Earthfix.  Accessed 1/31/2012 at:

Feely, R.A. et al. 2004. Impact of Anthropogenic CO2 on the CaCO3 System in the Oceans. Science 305: 362. Accessed 1/31/2012 at:

Goldman, J. 2011. Oceanographer named to head NOAA’s Seattle research laboratory. Noaa News.

Huseby, S. and Ettinger, B. 2009. A Sea Change.  Niijii Films.  Available at:

NOAA. 2010.  What is Ocean Acidification? PMEL Carbon Program.  Accessed 2/4/2012 at:

Sabine, C.L., et al. 2004. The Oceanic Sink for Anthropogenic CO2. Science 305:367-371.  Accessed 1/31/2012 at:

Sabine, C.L. 2011.  Ocean Uptake of Atmospheric CO2 and its Impact on Marine Ecosystems. Presentation Introduction. Aquatic Sciences Meeting, San Juan, Puerto Rico.

Sabine, C.L. 2012.  Interview, recorded with permission.

Sabine, C.L. 2012.  Email response to my chemistry questions.  Available upon request.

Sabine, C.L. and Feely, R.A. 2007. The Oceanic Sink for Carbon Dioxide. Pp 31-50 in Greenhouse Gas Sinks (eds D.S. Reay, N. Hewitt, J. Grace and K.A. Smith) CAB International.

Photo references

Feely.  2011. feelygliderphoto.  NOAA. Accessed 2/1/2012 at:

Gilmer, R.W. and Harbison, G.R. 2004. The pteropod Clio pyramidata.  Science 305:Cover.  Accessed 2/1/2012 at:

Goebel, Greg. 2006.  coal car, eastern Wyoming.  Accessed 1/31/2012 at:

Levin, M. 2007. Sabine and Feely photo. Ocean Blues. Columns: The University of Washington Alumni Magazine.  Accessed 2/4/2012 at:

NOAA. Research ship Oscar Dyson. Accessed 2/10/2012 at:

NOAA. 2007.  Sabine’s “Employee of the Month” Photo. Accessed 2/10/2012 at:

NOAA. 2010.  Sabine at sea. A Sea of Change: Ocean Acidification Threatening Coastal Waters. Accessed 2/4/2012 at:

NOAA. 2010.  What is Ocean Acidification? PMEL Carbon Program.  Accessed 2/4/2012 at:

NOAA. 2011.  National Oceanic and Atmospheric Administration.  Accessed 1/31/2012 at: