Stressed: Dying coral on a reef off the Florida Keys. Acidification is hurting coral and shell formation in oceans. (Scott Keeler/Times/Newscom)
World’s oceans turning acidic faster than expected
Acidification caused by carbon emissions could bring some oceans to a tipping point.
By Peter N. Spotts | Staff writer/ December 18, 2008 edition
Reporter Peter N. Spotts talks about the impact of higher carbon dioxide levels on the Humboldt squid.
Parts of the world’s oceans appear to be acidifying far faster than scientists have expected.
The culprit: rising levels of carbon dioxide in the atmosphere pumped into the air from cars, power plants, and industries.
The Southern Ocean represents one of the most high-profile examples. There, scientists estimate that the ocean could reach a biologically important tipping point in wintertime by 2030, at least 20 years earlier than scientists projected only three years ago. Among the vulnerable: a tiny form of sea snail that serves as food for a wide range of fish.
Similar trends are appearing in more temperate waters, say researchers.
The studies suggest the CO2-emission targets being considered for a new global warming treaty are likely to be inadequate to prevent significant, long-lasting changes in some ocean basins.
Scientists over the past decade have detected a clear shift toward acidity since preindustrial times. But that “is not really telling you the story” as it unfolds on smaller but ecologically important scales, says David Archer, a researcher at the University of Chicago who studies the global carbon cycle.
The new research draws on long-term data on changes in ocean chemistry and the effect of those changes on marine life. The data are giving scientists their first clear look at the importance of natural swings in sea-water acidification in estimating overall acidification trends and tipping points.
But even these new studies may be conservative. Recent global CO2 emissions have been outstripping so-called business-as-usual emissions scenarios, which assume that no country adopts climate-specific limits on emissions.
From a human perspective, ocean acidification is relative; no one is talking about dissolving surf boards. On the pH scale – which runs from strong acids such as battery acid to strong bases such as laundry bleach – the oceans fall on the base side of the spectrum. The oceans have a pH of 8. Distilled water is considered neutral, with a pH of 7. Battery acid has a pH of 1.
Typically, seawater is heavily saturated with dissolved calcium carbonate from eroded limestone. This neutralizes any acid that forms from CO2 and leaves plenty of carbonate for marine creatures to use for shell- and reef-building. But as oceans absorb increasing amounts of CO2 from fossil fuels, their stores of calcium carbonate dip. Over time, this reduces carbonate available for marine creatures. Shell and coral formation slows.
Once seawater is too deficient in carbonate, these creatures find it hard to form shells or corals at all. In fact, existing shells start to dissolve, notes Ben McNeil, a researcher at the University of New South Wales in Australia.
In a recent study, he and a colleague looked at trends in the Southern Ocean. Oceans at the top and bottom of the world might be expected to lead in acidification because cold water soaks up more CO2 than warm water. But the duo also found large seasonal swings in carbonate levels. They traced increases in the water’s relative acidity to strong wintertime winds off Antarctica that bring to the surface cold water from the deep, which has low levels of carbonate.
The challenge, Dr. McNeil says, is that this seasonal peak in acidification comes just as tiny swimming snails – which some call potato chips of the sea – exist as larvae. The tiny zooplankton, called pteropods, need carbonate to build their shells. They represent a vital source of food for many fish. Some pteropods already show signs of dissolving shells, the team reports.
With a business-as-usual emissions scenario, McNeil and his colleague estimate that the Southern Ocean is likely to reach a wintertime tipping point for these creatures when atmospheric CO2 concentrations reach 450 parts per million, versus today’s level of around 383 ppm. That would occur by 2030 and no later than 2038, they estimate. The results appear in the Dec. 9 issue of the Proceedings of the National Academy of Sciences (PNAS).
On Tatoosh Island, off the northwest tip of Washington State’s Olympic Peninsula, researchers have found acidification trends running some 10 times faster than projected. The University of Chicago’s Timothy Wootton led a team that analyzed more than 24,500 water samples gathered over eight years. They found wide swings in carbonate levels during the year. As acidification increased, they found, larger shell-forming creatures such as mussels and barnacles lost ground to smaller ones and nonshell types of algae. The team’s work also appears in the same issue of PNAS.
As acidification changes the mix of marine life in coastal areas, it could eliminate species important to commercial fisheries, they say.
The picture is more complicated in the Caribbean. Researchers with the National Oceanic and Atmospheric Administration (NOAA) and the University of Miami tracked changes in acidification across the greater Caribbean between 1996 and 2006 using sensors placed on a cruise ship and satellite data.
The region shows a definite trend toward acidification through a reduction in dissolved carbonates, with the highest seasonal swings seen in the waters around the Florida Keys. The results appeared in the Oct. 31 issue of the Journal of Geophysical Research.
The implication for the Keys is unclear, says Dwight Gledhill, a reef expert with NOAA who led the team. Reefs there have clearly adapted to large seasonal swings in minerals.
“If you have a system that shows large variability throughout the year, that could mean that the system may be more resilient to future changes,” he says. “[Or] do they cross a critical threshold sooner?”
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Comments
2. Arlene Hobbs | 12.19.08
There is a Calendar of Life’s Evolution on Earth from the very first worms and bugs throughout history. The ancient history of life on earth appears in layers of rock near the Dinosaur National Monument west of Denver, Colorado. It’s near the place where Highway 6 and I-70 meet. I always wondered about the black spaces between the advancing ages of new life forms.
Recently I saw a picture of the cool side of our sun on the internet with a sliver of the “hot side of our sun” appearing at the edge of the sun now turning toward us. It seems to me the “global warming” is not man made. It is the regular appearance of the hot side of our revolving sun.
Have our astronaughts seen a hot side of our sun?
3. Ron Scheurer | 12.19.08
Why not admit the real problem, and the fact that humans are incapable of doing anything about it; overpopulation to the tune of about 5 billion. Unless some natural catastrophe wipes out at least that many people inside of a year or less, no number of technological fixes are going to save us from near extinction.
It is not a question of being an optimist or pessimist. It is a question of being a realist, understanding the interplay of natural events, and working with those instead of believing in some god given right of dominion over the earth to with it as we please at the expense of the rocks, plants, and other animals.
How would humans eliminate 5 billion people on the planet inside of a year? They cannot even begin to imagine such a thing as self-extermination. But the means are certainly here in the form of WMD in the US, Russia, China, India, and possibly Pakistan.
I think it better that we let nature handle the problem. Or god if that is your preference.
4. mike Jefferis | 12.19.08
Note to Arlene Hobbs: If you want to find evidence that global warming is not human-powered, the “hot side of the sun” would not seem like a promising location. What mysterious “hot side” of solar celestial ball have we missed, as our little world travels 360 degrees around the sun every year?
On behalf of the oceans, and ourselves, we all must steadily use less petroleum and coal. That means driving less, using less electricity, using less material (of all kinds), using less heat. Buying less. Traveling less. Building less. Manufacturing less. It doesn’t matter whether the price of oil and coal falls or rises - what we need to do is use less of it.
5. James Stepp | 12.19.08
“As acidification changes the mix of marine life in coastal areas, it could eliminate species important to commercial fisheries, they say.”
My shiny white rear end. This isn’t the biggest danger as I see it. The biggest danger is if the phytoplankton in our oceans are no longer able to form their shells. Phytoplankton produce over 70% of our oxygen and if we wipe them out, well, a drop in oxygen levels of only about 20% takes humans out of our survival parameters.
To compount that, most of our technologies, whether it’s electrical generation by running a coal plant or driving our cars, burn huge amounts of oxygen. If we cause an extinction of phytoplankton the people who survive will be the ones who can buy oxygen to breathe.
6. James Stepp | 12.19.08
Arlene, a “hot side” of our sun?!? There is no such thing. Where did you see that? Our planet rotates around our sun, so if there was such a thing we would be exposed to it every day. The rotational orbit path of our planet around the sun does shift over time but there is no such thing as a hot side.
You didn’t happen to get it from a web site “debunking” global warming did you?
7. Peter Ravenscroft | 12.20.08
You noted “cold water soaks up more CO2 than warm water.” Right, that we have known since the nineteenth century. So, as the oceans warm, they give off CO2. How is it then that the coral reefs are supposed to dissolve because of increased acidity? Less dissolved CO2 means a higher pH. Or have I missed something?
Peter Ravenscroft
Geologist,
Closeburn, Queensland, Australia.
8. Ed | 12.21.08
Comments on websites only reiterate the point that policy should be left to informed scientists, not the idiots who think that spending 5 minutes on a cretin’s global-warming-debunking site makes them “climate experts”. Half the people who attempt to debunk climate change wouldn’t know a a radiative transfer equation from a hole in the ground. We should move this debate outside the realm of the common idiot and common politician (nearly one and the same), and attempt to salvage what is left of the future for humanity.
10. Arthur G. Swedlow | 12.26.08
Two points:
First I’d also like to know where the idea of a dark side of the sun came from. Depending on the latitude on the sun, it rotates in roughly 25-30 days and within a normal range of variability has shown no difference over periods of rotation.
Second, with respect to Peter’s fine point, I believe the answer has to do with the fact that temperature is not the only factor affecting gas solubility. The partial pressure of CO2 is the other driving force. Apparently its affect overshadows the effect of rising temperature.
11. Science Please | 04.19.09
Where on earth does this “fact” come from? “Typically, seawater is heavily saturated with dissolved calcium carbonate from eroded limestone.”
Sorry, but any first year geology student can explain to you that calcium carbonate in sea water is a product of evaporation not erosion.
Furthermore oceans (the Northern Atlantic to be specific as it is the only one proven to be warming) are degassing CO2 not absorbing more as CO2 solubility is a function of temperature.
The CSMonitor should be ashamed of passing of faulty logic as verifiable scientific fact.
Trackbacks/Pingbacks
2. OCEAN ACIDIFICATION: Coral growth rates are the lowest in 400 years, « The Conservation Report | 01.03.09
3. Southern Ocean Acidification: a Tipping Point at 450-ppm Atmospheric CO2 « RFF Library Blog | 01.09.09
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1. russ | 12.18.08
The focus of this article on the issue of ocean pH seems to emphasize the solubility issue of carbonates which is a physical chemists point of view. In fact the oceans are a living ecosystem and long before carbonate solubility acts on ocean life the pH acts through far more complicated mechanisms in living metabolism. Just as human and of recent reports giant squids respond to very slight changed in CO2 driven pH the myriad smaller more sensitive forms of sea life do as well. As many reports have shown the ocean plants are disappearing at rate far exceeding the loss of plant life in our rainforests. The Southern Ocean has lost 10% of its plant life in the past 25 years, the N. Atlantic 17%, the N. Pacific 26% and the sub-tropical tropical oceans 50%. That these horrific losses of ocean plants, primary productivity, have occurred the missing green plants which were converting 4-5 billion tons of CO2 each year into living biomass are failing in thier role of the most potent buffers of planetary CO2.
We must begin ocean eco-restoration immediately. We have a mere 21 years as some reports show before we are so far over the ‘tipping point’ there may be no return. The late great John Martin showed the way with his revelations of the role of diminishing mineral micronutrients in the collapsing ocean ecology. By replenishing Martins ocean iron healthy robust life filled oceans will return. If we succeed at restoring ocean health back to the state they were in 25 years ago each year the oceans will convert half the problem of global CO2 emissions into life instead of acidic death. Read more at http://www.planktos-science.com… call for governments to begin ocean eco-restoration now before it is too late.