Ocean Acidification: A Hidden Risk of Global Warming

I love swimming in the ocean, but I also know plenty of people who wouldn’t dream of it. There are too many unseen perils: the ominous tug of a current, razor-sharp oyster shells, sting rays buried in the sand and shadowy, slimy things brushing past. Even my fishermen friends, who depend on the ocean for their livelihoods, keep a respectful distance from the waves.

The ocean is awe-inspiring. We were born of it, and it gives us life by producing much of the oxygen we breathe and the water we drink. It is mysterious and vast. No wonder we speak of emptying oceans with teaspoons to describe impossible tasks.

Yet, unfathomably, we have accomplished the impossible. We have changed the basic chemistry of the oceans — drop by drop — in such a profound way that we may be destroying a web of life that we depend upon for our very existence. Those ocean creatures should be wary of us — not the other way around.

“Scientists are concerned that we are changing the ocean’s chemistry so rapidly that we are outstripping the evolutionary pace of many organisms to adapt.”

The change we’ve introduced is called ocean acidification.

The basic science is pretty straightforward: Since the industrial revolution, humans have been pumping ever increasing amounts of carbon dioxide into the air. Some of that CO2 is absorbed by the ocean, where it dissolves to form carbonic acid.

The ocean today absorbs nearly a third of the carbon dioxide we produce, probably mitigating the impact of climate change. But the ocean has absorbed so much CO2 that overall acidity levels are rising, and at a much faster rate than previously thought.

More acidic water makes it harder — and ultimately impossible — for some creatures like oysters, corals and mussels to form shells, which are made largely from the calcium carbonate, plain old chalk, that occurs naturally in seawater.  That’s why acidification is sometimes referred to as “osteoporosis of the sea.”

Photo by Victoria Fabry
These tiny, lentil-sized pteropods are essential to the survival of creatures like the humpback whale. (Top photo: Limacina Helicina by Victoria Fabry.)
Humpback Whale and Calf

This process affects creatures up and down the food chain — from the tiny organisms that build the planet’s coral reefs and the plankton drifting with the ocean currents, all the way to the whales that feed on the plankton.

Also affected are the lentil bean-sized pteropods, delicate, balletic creatures that nourish many of the fish we then consume. In other words, the ability of all ocean life to sustain itself is being compromised.

Scientists have been surprised at how sensitive plants and animals are to even small changes in CO2 levels. Some creatures have shown an ability to adapt to more acidic waters; lobsters, for instance, harden their shells in an initial response to acidity. But for many creatures, acid is deadly: Their shells disintegrate. And many scientists are concerned that we are changing the ocean’s chemistry so rapidly that we are outstripping the capacity of many organisms to adapt.

Because the science is fairly new, we still do not fully understand the long-term effect of increasingly acidic oceans. The ocean is a complex, integrated, self-regulating system; how it will change is hard to predict.

As we conduct this uncontrolled experiment on two-thirds of the planet, scientists are racing to find ways to make the ocean more resilient. Doug Rader, EDF’s chief ocean scientist, says: “Along with our partners from around the world — from Cuba to the EU, and beyond — EDF scientists are scrambling to understand why some reefs are more robust than others, why some fish populations bounce back, when others languish, and exactly what mix of strategies will suffice to maximize the resilience of the world’s oceans.

“One thing is already clear,” he adds. “Rebuilding ecosystem complexity, including restoring populations of large predators such as sharks, is central to the long-term survival of the seas.”

The Obama administration signaled its commitment to acidification research when it appointed Jane Lubchenco to head the National Oceanic and Atmospheric Administration (NOAA). Lubchenco, a widely respected marine ecologist and former EDF Board member, has made clear, in Congressional testimony and elsewhere, the seriousness of this threat to the seas.

There is no controversy surrounding the science underlying the acidification of the ocean. There is no question about where the CO2 is coming from. There is no question about how the chemistry works. And there is only one known way to stop acidification: to reduce emissions of carbon dioxide. The more we reduce now, the less severe, and costly, the future consequences.

What can you do? Become an advocate for the oceans. Take care to minimize your carbon footprint—but keep in mind one of my favorite phrases: living sustainably is necessary, but not sufficient. It’s equally important to demand comprehensive legislation that cuts carbon emissions.

And go ahead, take a swim. Bathe in those natal waters, and give thanks for the life they support. The ocean has the capacity to heal itself much faster than one teaspoon at a time. We need to give it that chance. We would be doing ourselves a big favor — giving our grandchildren a chance to inhabit a livable planet.

Personal Nature
Take action! Tell the Senate to cap the global warming pollution causing ocean acidification.

Editor’s note, 2/12: The list of animals that will experience difficulty in forming shells has been updated.

30 Responses

Comment from Julian Cole
February 5th, 2010 at 12:44 pm

It’s about our grandchildren and great-grandchildren. And it’s real. How will we explain to them?

Comment from Gail
February 5th, 2010 at 12:45 pm

More people need to understand how critical this issue is for terrestrial life, which is dependent on robust life in the sea for much of the oxygen production that sustains us. Here is a link to a beautifully filmed video that illustrates how sensitive the ocean food chain is to acidification: http://witsendnj.blogspot.com/2009/10/you-cant-fish-and-not-have-hope.html

Comment from Rebecca Cramer
February 5th, 2010 at 12:55 pm

Beautifully-written essay; so, so important a topic. But, I carp: the “2” in the chemical formula for carbon dioxide should, I believe, be a sub-script, not a super-script. Small point, but I wouldn’t want anyone to dismiss the importance of the topic for a mistake in editing.

Comment from Sara Ransom
February 5th, 2010 at 1:01 pm

Along what is now called the Mexican Riviera, the city of Lazaro Cardenas is home to a Japanese steel plant which emits pollutions into the sea… I have only my personal observations of the effects. Where once there were beautiful and plentiful little tropical fish in tidepools, at the rivermouth of La Saladita, there is now brown growth on the rocks. Perhaps trained scientists from EDF could check this out.

Comment from Chris Rathbun
February 5th, 2010 at 1:18 pm

“It’s about our grandchildren and great-grandchildren. And it’s real. How will we explain to them?”

Not to worry- either we get a grip on this problem, or the world will be uninhabitable for humans and there will be no great grandchildren to have to explain to.

Comment from David Allison
February 5th, 2010 at 1:20 pm

Goverment need to look at this immediatly as their number one priority. It is for the future of our families and the rest of life of the planet.

Comment from J Steele
February 5th, 2010 at 1:24 pm

Ocean acidification will hopefully enlist the nay-sayers of climate change to account for the incontrovertible human impact on the Earth’s ocean and work towards necessary change. We recently screened a beautiful film on the subject at our Community Hall called A Sea Change by Barbara Ettinger (Niijii Films). This film is inter-generational, personally moving, and informative, as well as being visually stunning. And kudos to Sigourney Weaver for pressing the point on ocean acidification during her FOX interview, despite their foolish attempts to trivialize the matter.

Comment from Dave McArthur
February 5th, 2010 at 3:14 pm

Thank you Dominique. A lovely meditation is to gaze upon the horizon if you are fortunate to live by the ocean. Simply gaze at it just seeing what is to be seen – the shifting patterns of the ocean surface and sky and their reflections in each other. At such times the horizon can dissolve and the ocean and atmosphere are experienced as one. One becomes aware of the immense dynamic of the water cycle and with that the interplay of less visible gases in the ocean-air comes alive. I find it an awesome and humbling experience to reflect on my role in this amazing system. It makes nonsense of those who speak of a low carbon/zero carbon/carbon offset/post carbon world for whatever reason. I find myself searching for symbol uses that reflect the wonder of carbon and our need to conserve our carbon potential, which includes the balances of the ocean-air system that sustains us. You can view photos of the ocean-air world I enjoy at

Comment from dave
February 5th, 2010 at 3:16 pm

Its all about where all the carbon dioxide ends up. There is some great information at NOAA and WHOI.




The Socioeconomic Costs of Ocean Acidification

Seawater’s lower pH will affect food supplies, pocketbooks, and lifestyles


Comment from windman922
February 5th, 2010 at 3:29 pm

For several years I and other retired scientific types have been studying ways to reduce our use of fossil fuels. We have concluded that we must shut down the coal burning power plants. See http://www.coal2nuclear.com/ how that can be done quickly. Please inform others of this method so that we can generate the political will to save our world.

Comment from Archer V Elmendorf Jr
February 5th, 2010 at 4:49 pm

We must remember the old Indian adage, “We did not inherit this world from our Forefathers, we have borrowed it from our offspring!” It is our children and grandchildren… and their grandchildren… that will pay the cost of our transgressions. A Kenyan proverb puts it this way:
“Treat the world well. It was not given to you by your parents. It was lent to you by your children.” We must all learn how to “Treat the world well,” and teach others.

Comment from Micheal Clark
February 5th, 2010 at 5:10 pm

Until we are ready to control the over all population of the human race and begin to reduce human numbers through birth control world wide, Mother earth and by proxy all life on earth is doomed. All of the ills that the earth suffers are syptoms of the same disease. That disease is over population.

Comment from Brian Cady
February 5th, 2010 at 5:46 pm

There’s an error:
“More acidic water makes it harder — and ultimately impossible — for creatures like mussels, clams, lobsters and crabs to form shells, which are made largely from the calcium carbonate, plain old chalk, that occurs naturally in seawater. Acidic water simply eats away the calcium carbonate”
Lobsters and crabs’ shells are not of calcium carbonate; they are of chitin, a carbohydrate:


Comment from Tom V
February 5th, 2010 at 6:15 pm

I don’t buy it, at least not from this piece. If you drop a seashell into hydrochloric acid, it will dissolve. But carbonic acid is a weak acid — think seltzer or soda water, both loaded with carbon dioxide. Does drinking that stuff dissolve your teeth? No.

This article is ambiguous and empty of key facts, like what concentration of carbonic acid, if there is one, that will cause serious damage to sea life? And, what levels of carbon dioxide would have to be in the atmosphere to achieve those carbonic acid levels?

Without such key facts, I have to view this as nothing more than a baseless scare piece.

Comment from Joe
February 5th, 2010 at 6:22 pm

We all are going around the main causes of global warming and that is human population growth. Slow down the population growth by mandatory 2 children per family and the rest will follow!!!!!! More regulations with growth will not slow or stop the problem!!!

Comment from stipeybabe
February 5th, 2010 at 6:44 pm

I feel it’s time for those who just ignore everything to open their eyes and fast. This is the Real World. My concern is what’s going to happen to our children’s children one day because the Environment doesn’t just clear up just like that it needs TLC and if we don’t decide to look after these very important issues that we face day after day something will eventually happen and yeah it’s a scary issue but it must be dealt with. Not next week But Here And Now.

Comment from Marilyn
February 5th, 2010 at 8:00 pm

Hmmm- I think the problem is bigger than just carbon dioxide. Why doesn’t anyone talk about the chemicals that we are pumping in the Earth and water on a daily basis, from our homes. If you are using Tide, Cheer, anti-bacterial handsoaps, Bath and Bodyworks fragranced body products, etc., you are part of the problem. These chemical products end up in the oceans and Great Lakes. Please check out http://www.ourwaterlife.com and read the Seattle Times article, ‘Puget Sound: Down the Drain’. Also check out ‘CBC Doczone: The Disappearing Male’, and ‘PBS Frontline:Poisoned Waters’. We are polluting the Earth and altering our children, so they may not be able to reproduce in the future- sounds crazy but it is true.

Comment from Marilyn
February 5th, 2010 at 8:02 pm

P.S. There is a solution- you don’t have to live like cavemen- just use good green products that biodegrade back to Nature.

Comment from paul
February 5th, 2010 at 8:33 pm

Hi there,
I recently published an ocean acidification resource page (including the Lubchenco videos and others) here:


and a pdf on ocean acidification here:


both provide in-depth coverage of this issue. The executive summary of the report was also featured on the Doctors for the Environment – Australia (of which I am a member) website:


From my report:
We don’t have long to turn things around.
Ocean acidification is already making the calcified parts of some sea creatures thinner and lighter.
Coral reefs are going to start disappearing by 2050 at the latest.
This is starting to happen right now, independent of global warming.
It has the same solution though – rapid emissions reduction.
Due to the long lag-times in the system, the quicker we reduce carbon dioxide emissions, the more effect it will have in the future.
Tell someone about this problem.
Share this document.
Visit my website for more information.
Do something today!!!

Paul Roth

Comment from The Effects Of Global Warming
February 6th, 2010 at 12:38 pm

So ok, there is no global warming. So what happens to all the pollution from the factories and vehicles? Absorbed by trees and turn into apples?

Comment from John Fitzgerald
February 6th, 2010 at 1:22 pm

Yes there is a mistake in attributing calcium carbonate to lobsters and crabs. Bad research, doesn’t help the cause and attracts doubters and deniers like moths to a light.It is molluscs and brachiopods, to mention but a few,whose exoskeleton is made of calcium carbonate. This is another aspect to the deadly outcomes of putting excess carbon in the atmosphere and could see our beautiful oceans become “dead zones” if the fragile ocean ecosystem collapses. Please try and be more accurate.

Comment from Catherine Mc Manus
February 6th, 2010 at 10:43 pm

Thanks for posting your wonderful blog.
Unfortunately Al Gore and “Global Warming” are getting such bad press these days. Every time I see blogs bashing
Al & GLobal Warming I inform them whether they believe Al Gore or not to think about Man’s POLLUTION. I try to explain that GLOBAL WARMING is not just referring to melting Ice Caps. We need to explain it is not just a “political” ploy to sell Green Technology. To me Global Warming means EXTREME WEATHER CHANGES caused by
Human pollution of all kinds. Not just Warming, but colder, windier, droughts, floods, etc. Way back in the 1970’s we were warned of OZONE LAYER HOLES FORMING. People just do not understand and the current bad press is not helping to inform of all the detrimental effects/affects caused by humans abusing our earth.
are continuing to cause.

Comment from Catherine Mc Manus
February 6th, 2010 at 10:46 pm

Please pardon my typos and poor editing…
as you can see I get a bit over excited and carried away.

Comment from Steven
February 7th, 2010 at 5:53 pm

Unfortunately Tom V knows nothing about ocean chemistry which is typical of the reason why we are destroying the planet with naysayers preventing the necessary action.

Comment from merlin
February 10th, 2010 at 2:26 am

i know and i do believe that alot of things are happening in this world which we overlook and it begins right from “I”. We are to be blamed for all the changes and destruction in this world for not standing up and making it right. i would not like to comment much as i would love to first educate myself then bring awareness into others. That is why i wish all organisations would give their views in educating the world with asking no much benefits of expense. this is why many people would rather turn back on viewing a certain site which recommends a purchase. maybe to an small extent we could educate free of cost inorder to save the globe not to say everything goes free of cost as to earn benefits from others hard work. i love all that your organisation is doing and wish to learn more as i too am in a field of social service. all the best.

Comment from James Richard Tyrer
February 10th, 2010 at 5:13 am

It is unfortunate that this article was written in scare speak. The whole premise of the article that acid is going to eat the shells of mollusks and other sea creatures is not scientifically correct.

The fact is that Calcium Carbonate is slightly soluble in water and that this solubility is increased by the addition of Carbon Dioxide to the water. The resulting reaction forms Bicarbonate ions. This is not a sudden violent reaction like when you throw a sea shell in Hydrochloric Acid. But, rather it is an equilibrium reaction that can be driven either way by an increase in the the reactants on either side of the equation.

As the Ocean water absorbs more Carbon Dioxide, it will dissolve more Calcium Carbonate, but this reaction will not continue unless more Carbon Dioxide is added. The total alkalinity in the Oceans acts as a buffer and the absorbed Carbon Dioxide does not make a large change in the pH as it would in pure water.

It should also be noted that the Oceans are NOT acidic and they are not going to become acidic any time soon. They are still alkaline at a pH of greater than 8.

But the various scientific errors in chemistry do not mean that there isn’t a problem. It only means that the EDF needs a fact checker.

The increasing Carbon Dioxide levels in the Oceans are harmful to animal life. Although it is not really certain just how much of a threat it is. The main cause of Coral bleaching is not Carbon Dioxide but rather changes in water temperature. And some animals (IIUC, the ones with chitin shells) seem to be growing thicker shells as the level of absorbed Carbon Dioxide increases. And of course the Algae like the increase in Carbon Dioxide although there is a shortage of nutrients in the Oceans. So, my point is that is isn’t simple, although the changes caused by increases in the Ocean Carbon Dioxide levels are certainly not a good thing.

Comment from R Margolis
February 12th, 2010 at 1:37 pm

For me, it was actually the acidifcation of the oceans that got my attention to the CO2 issue. The debate has become so shrill with respect to the computer models that the real observable effects are being ignored.

Comment from Trish McDermott
February 17th, 2010 at 5:48 pm

Reply from Doug Rader, EDF’s Chief Oceans Scientist

“Actually, Brian, many crustaceans — including most lobsters and crabs — have shells made out of both chitin and carbonates. The chitin provides the flexible elements, including those that allow a molting crab to squeeze out of it’s old shell, while the carbonates provide the protection that develops as the recently molted crab shell “hardens.” Making calcium carbonate minerals harder to make has real importance to many crustaceans. In fact, recent and developing science shows a variety of responses in different crustaceans to experimental acidification, including shell thinning in some and shell thickening in others. Either way, the potential cost is high (ecologically or energetically). There is still lots to learn on this subject.

Here’s an article you may find interesting about the prospective economic costs of ocean acidification, from scientists at Woods Hole:


Comment from alkaline foods list
March 1st, 2010 at 2:19 am

I find it an awesome and humbling experience to reflect on my role in this amazing system. It makes nonsense of those who speak of a low carbon/zero carbon/carbon offset/post carbon world for whatever reason.

Comment from OLSON31Erika
March 7th, 2010 at 1:38 pm

I received my first personal loans when I was 20 and it helped my relatives very much. However, I need the collateral loan again.

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