Modern ocean acidification is outpacing ancient upheaval, study suggests

Jun 02, 2014
The deep-sea benthic foram Aragonia velascoensis went extinct about 56 million years ago as the oceans rapidly acidified. Credit: Ellen Thomas/Yale University

Some 56 million years ago, a massive pulse of carbon dioxide into the atmosphere sent global temperatures soaring. In the oceans, carbonate sediments dissolved, some organisms went extinct and others evolved.

Scientists have long suspected that played a part in the crisis—similar to today, as manmade CO2 combines with seawater to change its chemistry. Now, for the first time, scientists have quantified the extent of surface from those ancient days, and the news is not good: the oceans are on track to acidify at least as much as they did then, only at a much faster rate.

In a study published in the latest issue of Paleoceanography, the scientists estimate that surface ocean acidity increased by about 100 percent in a few thousand years or more, and stayed that way for the next 70,000 years. In this radically changed environment, some creatures died out while others adapted and evolved. The study is the first to use the chemical composition of fossils to reconstruct surface at the Paleocene-Eocene Thermal Maximum (PETM), a period of intense warming on land and throughout the oceans due to high CO2.

"This could be the closest geological analog to modern ocean acidification," said study coauthor Bärbel Hönisch, a paleoceanographer at Columbia University's Lamont-Doherty Earth Observatory. "As massive as it was, it still happened about 10 times more slowly than what we are doing today."

The oceans have absorbed about a third of the carbon humans have pumped into the air since industrialization, helping to keep temperatures lower than they would be otherwise. But that uptake of carbon has come at a price. Chemical reactions caused by that excess CO2 have made seawater grow more acidic, depleting it of the carbonate ions that corals, mollusks and calcifying plankton need to build their shells and skeletons.

In the last 150 years or so, the pH of the oceans has dropped substantially, from 8.2 to 8.1—equivalent to a 25 percent increase in acidity. By the end of the century, ocean pH is projected to fall another 0.3 pH units, to 7.8. While the researchers found a comparable pH drop during the PETM—0.3 units—the shift happened over a few thousand years.

Modern ocean acidification is outpacing ancient upheaval, study suggests
Ocean acidification in the modern ocean may already be affecting some marine life, as shown by the partly dissolved shell of this planktic snail, or pteropod, caught off the Pacific Northwest. Credit: Nina Bednaršedk/NOAA

"We are dumping carbon in the atmosphere and ocean at a much higher rate today—within centuries," said study coauthor Richard Zeebe, a paleoceanographer at the University of Hawaii. "If we continue on the emissions path we are on right now, acidification of the surface ocean will be way more dramatic than during the PETM."

Ocean acidification in the modern ocean may already be affecting some marine life, as shown by the partly dissolved shell of this planktic snail, or pteropod, caught off the Pacific Northwest.

The study confirms that the acidified conditions lasted for 70,000 years or more, consistent with previous model-based estimates.

"It didn't bounce back right away," said Timothy Bralower, a researcher at Penn State who was not involved in the study. "It took tens of thousands of years to recover."

From seafloor sediments drilled off Japan, the researchers analyzed the shells of plankton that lived at the surface of the ocean during the PETM. Two different methods for measuring ocean chemistry at the time—the ratio of boron isotopes in their shells, and the amount of boron —arrived at similar estimates of acidification. "It's really showing us clear evidence of a change in pH for the first time," said Bralower.

What caused the burst of carbon at the PETM is still unclear. One popular explanation is that an overall warming trend may have sent a pulse of methane from the seafloor into the air, setting off events that released more earth-warming gases into the air and oceans. Up to half of the tiny animals that live in mud on the seafloor—benthic foraminifera—died out during the PETM, possibly along with life further up the food chain.

Other species thrived in this changed environment and new ones evolved. In the oceans, dinoflagellates extended their range from the tropics to the Arctic, while on land, hoofed animals and primates appeared for the first time. Eventually, the oceans and atmosphere recovered as elements from eroded rocks washed into the sea and neutralized the acid.

Today, signs are already emerging that some marine life may be in trouble. In a recent study led by Nina Bednaršedk at the U.S. National Oceanic and Atmospheric Administration, more than half of the tiny planktic snails, or pteropods, that she and her team studied off the coast of Washington, Oregon and California showed badly dissolved shells. Ocean acidification has been linked to the widespread death of baby oysters off Washington and Oregon since 2005, and may also pose a threat to coral reefs, which are under additional pressure from pollution and warming ocean temperatures.

"Seawater carbonate chemistry is complex but the mechanism underlying acidification is very simple," said study lead author Donald Penman, a graduate student at University of California at Santa Cruz. "We can make accurate predictions about how carbonate chemistry will respond to increasing levels. The real unknown is how individual organisms will respond and how that cascades through ecosystems."

Explore further: Researchers discover ocean acidity is dissolving shells of tiny snails off the US West Coast

More information: Paper: onlinelibrary.wiley.com/doi/10… 014PA002621/abstract

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Maggnus
4.3 / 5 (17) Jun 02, 2014
The CO2 driving the climate change and ocean acidification 55 million years ago occurred over a period of a few thousand years and had a profound effect on the planet.

We are doing the same thing, but instead of thousands of years, it's happening in hundreds. Even tens.

How can people not be alarmed by this? What the hell has to happen to make some people understand what over 95% of our planet's best scientific minds are saying is occurring right in front of our eyes?
ubavontuba
1.6 / 5 (14) Jun 02, 2014
The CO2 driving the climate change and ocean acidification 55 million years ago occurred over a period of a few thousand years and had a profound effect on the planet.

We are doing the same thing, but instead of thousands of years, it's happening in hundreds. Even tens.

How can people not be alarmed by this? What the hell has to happen to make some people understand what over 95% of our planet's best scientific minds are saying is occurring right in front of our eyes?
Oh brother, this is old. Let's think of new ways to strike fear into the populace over benign CO2, shall we?

http://wattsupwit...s-again/

aksdad
2 / 5 (12) Jun 02, 2014
By the end of the century, ocean pH is projected to fall another 0.3 pH units, to 7.8

This projection, also noted in IPCC AR5, is based on CMIP5 earth system (computer) models, not on actual observations.

Station Aloha off Hawaii has measure ocean pH since 1988.
http://hahana.soe...nds.html

The trend since 1988, which appears to be linear and not accelerating is -0.001875 per year or about -0.19 per century. That means, by 2100, ocean pH will be approximately 7.9, or about 0.165 pH units. That's half the amount projected.

U.S. CO2 emissions declined 10% in the last 8 years without any government regulation of CO2; largely due to using natural gas instead of coal, and more efficient production and use of energy. European CO2 emissions have similarly declined. Problem is, developing countries like India and China are emitting more. They're the problem, but as their economies grow their energy production and use will also become more efficient.
howhot2
4.2 / 5 (15) Jun 02, 2014
It figures that the deniers would try to quickly target this article for a disinformation campaign. The claims of the article are bold and correct. Using fossils from the Paleocene-Eocene Thermal Maximum (PETM), a period of intense warming on land and throughout the oceans due to high CO2, scientist estimate that surface ocean acidity increased by about 100 percent in a few thousand years or more, and stayed that way for the next 70,000 years. So if you look at today's level of CO2 and the creeping acidification of the ocean, our excessive CO2 pollution will be effecting earth for the next 70,000 years.

I know most deniers are saying "yeah.. yeah.. bull", but suppose it wasn't bull and the oceans are killed, not of life, but of productive life? How would you feel about 400 ppm CO2 levels then?

thermodynamics
4.1 / 5 (15) Jun 02, 2014
Assdad said:
The trend since 1988, which appears to be linear and not accelerating is -0.001875 per year or about -0.19 per century. That means, by 2100, ocean pH will be approximately 7.9, or about 0.165 pH units. That's half the amount projected.


And your calibrated eye is much better than the supercomputer that made the other estimate?

Are you sure it is linear? What is your uncertainty and how did you project that uncertainty forward? Did you do a simulation? Do you know what a simulation is?
Nichol
2.6 / 5 (5) Jun 03, 2014
It is time to start trying to do something to speed up the natural weathering of silicates, where especially olivine seems promising. It can be mined, ground up, and then put out in rough seas on the coast, or mixed with soil on land to be weathered by organic activity. As far as I can find, this is the mildest form of geoengineering, with no obvious bad side effects if one carefully, and one that attacks ocean acidification first.
dogbert
1.7 / 5 (11) Jun 03, 2014
In the last 150 years or so, the pH of the oceans has dropped substantially, from 8.2 to 8.1—equivalent to a 25 percent increase in acidity.


A pH of 8.2 or even 8.1 is no where near acidic. These pH's are basic.
Maggnus
4.3 / 5 (12) Jun 03, 2014
In the last 150 years or so, the pH of the oceans has dropped substantially, from 8.2 to 8.1—equivalent to a 25 percent increase in acidity.


A pH of 8.2 or even 8.1 is no where near acidic. These pH's are basic.
Interesting that someone who obviously has no idea what he is talking about feels the need to spout his ignorance out loud for all to hear.
dogbert
1.8 / 5 (13) Jun 03, 2014
Maggnus,

A pH of 7.0 is neutral. Anything over 7.0 is alkaline. Anything under 7.0 is acidic.

The oceans are not acidic and are unlikely to become acidic any time soon.

Where were you misled about pH?
runrig
4.4 / 5 (14) Jun 03, 2014
Maggnus,

A pH of 7.0 is neutral. Anything over 7.0 is alkaline. Anything under 7.0 is

The oceans are not acidic and are unlikely to become acidic any time soon.

No one said the oceans are acidic!
Just that they are becoming MORE acidic - at a rate of knots.
"Ocean acidification is the reduction in the pH of the ocean caused primarily by uptake of CO2 from the atmosphere, but also caused by other chemical additions to or subtractions from the ocean...."
http://oceanacidi...ion.aspx
barakn
4.4 / 5 (13) Jun 03, 2014
Dogbutt is clueless as usual. Acidity is a measure of the concentration of hydrogen ions (or perhaps more properly hydronium ions). Hydrogen ions do not magically disappear at pH 7. Instead pH 7 is when the concentration of hydrogen and hydroxide ions are roughly equal. At higher pHs hydrogen ion concentration decreases but by no means completely disappears. It is perfectly acceptable in the chemistry world to speak of acidity in water with a pH larger than 7. So where was Dogbutt misled about pH?
edward_j_kirby
4.3 / 5 (12) Jun 03, 2014
Oh brother, this is old. Let's think of new ways to strike fear into the populace over benign CO2, shall we?


This is like saying don't worry about drowning in the ocean because H2O is
"benign".
ubavontuba
2.1 / 5 (7) Jun 04, 2014
Maggnus,

A pH of 7.0 is neutral. Anything over 7.0 is alkaline. Anything under 7.0 is

The oceans are not acidic and are unlikely to become acidic any time soon.

No one said the oceans are acidic!
Just that they are becoming MORE acidic - at a rate of knots.
"Ocean acidification is the reduction in the pH of the ocean caused primarily by uptake of CO2 from the atmosphere, but also caused by other chemical additions to or subtractions from the ocean...."
http://oceanacidi...ion.aspx
So if it was the other way, and the oceans were highly acidic, would we say "becoming more alkaline," or "neutralizing?"

ubavontuba
1.4 / 5 (9) Jun 04, 2014
Oh brother, this is old. Let's think of new ways to strike fear into the populace over benign CO2, shall we?
This is like saying don't worry about drowning in the ocean because H2O is "benign".
I don't worry about drowning in the ocean, either, even though H2O is exceptionally more dangerous than CO2. Why should I?

Maggnus
4.4 / 5 (7) Jun 04, 2014
Maggnus,

A pH of 7.0 is neutral. Anything over 7.0 is alkaline. Anything under 7.0 is

The oceans are not acidic and are unlikely to become acidic any time soon.

No one said the oceans are acidic!
Just that they are becoming MORE acidic - at a rate of knots.
"Ocean acidification is the reduction in the pH of the ocean caused primarily by uptake of CO2 from the atmosphere, but also caused by other chemical additions to or subtractions from the ocean...."
http://oceanacidi...ion.aspx
So if it was the other way, and the oceans were highly acidic, would we say "becoming more alkaline," or "neutralizing?"

Yes.
rockwolf1000
4.2 / 5 (10) Jun 04, 2014
This is like saying don't worry about drowning in the ocean because H2O is "benign". I don't worry about drowning in the ocean, either, even though H2O is exceptionally more dangerous than CO2. Why should I?



More nonsense from ubamoron. In the context of being in the ocean H2O is not specifically dangerous at all. Becoming submerged in any liquid or even dense gases is potentially fatal whether it be H2O, milk, SF6 or urine. So to say H2O is dangerous is false. If it is so is milk.

CO2 on the other hand is not immediately dangerous in low concentrations, but, when it is being spewed into the atmosphere at an ever increasing rate that is sufficient to alter the composition of the atmosphere that is dangerous. Simply because we do not know what will happen. If 97% of scientists said feeding your kids rhubarb leaves is dangerous would you just feed more to see what happens? You would wouldn't you? That's because you're sick.
Depraved. Demented. Plain stupid.
FastEddy
1 / 5 (5) Jun 10, 2014
The CO2 driving the climate change and ocean acidification 55 million years ago occurred over a period of a few thousand years and had a profound effect on the planet. ... We are doing the same thing, but instead of thousands of years, it's happening in hundreds. Even tens.

How can people not be alarmed by this? ...


Because we were not there 56 Million years ago?

"Some 56 million years ago, a massive pulse of global temperatures into the atmosphere sent global carbon dioxide levels soaring ..."