Ocean Warming, NOT Acidification, Impacts Calicified Plankton (coccolithophore) Growth

Ocean warming, not acidification, controlled coccolithophore response during past greenhouse climate change

Authors:

Gibbs et al

Abstract:

Current carbon dioxide emissions are an assumed threat to oceanic calcifying plankton (coccolithophores) not just due to rising sea-surface temperatures, but also because of ocean acidification (OA). This assessment is based on single species culture experiments that are now revealing complex, synergistic, and adaptive responses to such environmental change. Despite this complexity, there is still a widespread perception that coccolithophore calcification will be inhibited by OA. These plankton have an excellent fossil record, and so we can test for the impact of OA during geological carbon cycle events, providing the added advantages of exploring entire communities across real-world major climate perturbation and recovery. Here we target fossil coccolithophore groups (holococcoliths and braarudosphaerids) expected to exhibit greatest sensitivity to acidification because of their reliance on extracellular calcification. Across the Paleocene-Eocene Thermal Maximum (56 Ma) rapid warming event, the biogeography and abundance of these extracellular calcifiers shifted dramatically, disappearing entirely from low latitudes to become limited to cooler, lower saturation-state areas. By comparing these range shift data with the environmental parameters from an Earth system model, we show that the principal control on these range retractions was temperature, with survival maintained in high-latitude refugia, despite more adverse ocean chemistry conditions. Deleterious effects of OA were only evidenced when twinned with elevated temperatures.

Emeishan Volcanism's Impact on the Guadalupian/Capitanian Permian Mass Extinction

Submarine palaeoenvironments during Emeishan flood basalt volcanism, SW China: Implications for plume–lithosphere interaction during the Capitanian, Middle Permian (‘end Guadalupian’) extinction event

Authors:

Jerram et al

Abstract:

Plume-induced lithospheric uplift and erosion are widely regarded as key features of large igneous province (LIP) emplacement, as is the coincidence of LIP eruption with major extinction and oceanic anoxic events (OAE). The Emeishan LIP, which erupted during the Capitanian (previously termed ‘end Guadalupian’) extinction event, has provided the most widely discussed example of axisymmetric doming above a rising mantle ‘plume’; advocates have argued that in excess of 500 m of uplift occurred over greater than 30 000 km2 causing extensive radially distributed erosion and alluvial fan formation. However, the recognition of submarine hydromagmatic and phreatomagmatic-style volcanism, as well as syn-volcanic marine sediments interbedded in the eruptive succession, now requires further examination to this simple plume–uplift model.

Here we present data from newly discovered sections from the center of the putative uplifted area (around Lake Er Hai, SW Yunnan Province,) that provide a more complete history of the Emeishan volcanism. These reveal that platform carbonate deposition was terminated by rapid subsidence, followed quickly by the onset of volcanism. Importantly, these eruptions also coincide with widespread losses amongst fusulinacean foraminifera and calcareous algae. For at least the lower two thirds of the 4–5 km thick lava pile, eruptions continued at or below sea level, as testified by the presence of voluminous mafic volcaniclastic deposits, pillow lavas, and development of syn-volcanic reefal limestones in the Emeishan inner zone. Only in the later stages of eruption did terrestrial lava flows become widely developed. This onset of volcanism in a submarine setting and the consequent violent, phreatomagmatic-style eruptions would have had a profound effect on marine fauna and exacerbated any volcanically induced climate effects during the Capitanian. The late Permian of SW China at the time of the Emeishan was an extended area of thinned lithosphere with epeiric seas, which appear to have been sustained through the onset of LIP emplacement. Therefore, while there remains substantial geochemical support of a plume origin for Emeishan volcanism, LIP emplacement cannot be ubiquitously associated with regional pre-eruption uplift, particularly where complex lithospheric structure exists above a plume.

SURPRISE! Coccolithophores, Calcium Shelled Plankton, Actually Grow MORE With Increased Carbon dioxide, NOT Less

Coccolithophores--tiny calcifying plants that are part of the foundation of the marine food web--have been increasing in relative abundance in the North Atlantic over the last 45 years, as carbon input into ocean waters has increased. Their relative abundance has increased 10 times, or by an order of magnitude, during this sampling period. This finding was diametrically opposed to what scientists had expected since coccolithophores make their plates out of calcium carbonate, which is becoming more difficult as the ocean becomes more acidic and pH is reduced.

These findings were reported in the November 26th edition of Science and based on analysis of nearly a half century of data collected by the long-running Sir Alister Hardy Foundation (SAHFOS) Continuous Plankton Recorder sampling program.

"The results show both the power of long-term time-series of ocean observations for deciphering how marine microbial communities are responding to climate change and offer evidence that the ocean garden is changing," said Dr. William Balch, senior research scientist at Bigelow Laboratory for Ocean Sciences and a co-author of the paper. "We never expected to see the relative abundance of coccolithophores to increase 10 times in the North Atlantic over barely half a century. If anything, we expected that these sensitive calcifying algae would have decreased in the face of increasing ocean acidification (associated with increasing carbon dioxide entering the ocean from the burning of fossil-fuels). Instead, we see how these carbon-limited organisms appear to be using the extra carbon from CO2 to increase their relative abundance by an order of magnitude.

"This provides one example on how marine communities across an entire ocean basin are responding to increasing carbon dioxide levels. Such real-life examples of the impact of increasing CO2 on marine food webs are important to point out as the world comes together in Paris next week at the United Nations Conference on Climate Change," Balch added.

"Something strange is happening here, and it's happening much more quickly than we thought it should," said Anand Gnanadesikan, associate professor in the Morton K. Blaustein Department of Earth and Planetary Sciences at Johns Hopkins and one of the study's five authors.

link.

Why the Atlantic Ocean was More Acidified During the Paleocene Eocene Thermal Maximum

Around 55 million years ago, an abrupt global warming event triggered a highly corrosive deep-water current through the North Atlantic Ocean. The current's origin puzzled scientists for a decade, but an international team of researchers has now discovered how it formed and the findings may have implications for the carbon dioxide emission sensitivity of today's climate.

The researchers explored the acidification of the ocean that occurred during a period known as the Paleocene Eocene Thermal Maximum (PETM), when the Earth warmed 9 degree Fahrenheit in response to a rapid rise in carbon dioxide in the atmosphere and subsequently one of the largest-ever mass extinctions occurred in the deep ocean. They report their findings in today's (May 11) issue of Nature Geoscience.

This period closely resembles the scenario of global warming today.

"There has been a longstanding mystery about why ocean acidification caused by rising atmospheric carbon dioxide during the PETM was so much worse in the Atlantic compared to the rest of the world's oceans," said lead author Kaitlin Alexander, ARC Centre of Excellence for Climate System Science, University of New South Wales, Australia. "Our research suggests the shape of the ocean basins and changes to ocean currents played a key role in this difference. Understanding how this event occurred may help other researchers to better estimate the sensitivity of our climate to increasing carbon dioxide."

To get their results the researchers recreated the ocean basins and land masses of 55 million years ago in a global climate model.

During that time a ridge on the ocean floor existed between the North and South Atlantic that separated the deep water in the North Atlantic from the rest of the world's oceans. The ridge was like a giant bathtub on the ocean floor.

The simulations showed this ridge became filled with extremely corrosive water from the Arctic Ocean, which mixed with dense salty water from the Tethys Ocean and sank to the seafloor, where it accumulated. The sediment in this area indicates the water was so corrosive that it dissolved all the calcium carbonate produced by organisms that settled on the ocean floor.

When the Earth warmed as a result of a rapid increase in atmospheric carbon dioxide, it eventually warmed this corrosive bottom water. As this water warmed it became less dense and denser water sinking from above replaced it. The corrosive deep water was pushed up and spilled over the edge of the giant "bathtub" and flowed into the South Atlantic.

link.

Ocean acidification was one of the Kill Mechanisms of the Permian Extinction

Ocean acidification and the Permo-Triassic mass extinction

Authors:

Clarkson et al

Abstract:

Ocean acidification triggered by Siberian Trap volcanism was a possible kill mechanism for the Permo-Triassic Boundary mass extinction, but direct evidence for an acidification event is lacking. We present a high-resolution seawater pH record across this interval, using boron isotope data combined with a quantitative modeling approach. In the latest Permian, increased ocean alkalinity primed the Earth system with a low level of atmospheric CO2 and a high ocean buffering capacity. The first phase of extinction was coincident with a slow injection of carbon into the atmosphere, and ocean pH remained stable. During the second extinction pulse, however, a rapid and large injection of carbon caused an abrupt acidification event that drove the preferential loss of heavily calcified marine biota.

pop sci write up.

Evidence of Ocean Acidification After the Marinoan Glaciation From Cryogenian NeoProterozoic China

Ocean acidification in the aftermath of the Marinoan glaciation

Authors:

Ohnemueller et al

Abstract:

Boron isotope patterns preserved in cap carbonates deposited in the aftermath of the younger Cryogenian (Marinoan, ca. 635 Ma) glaciation confirm a temporary ocean acidification event on the continental margin of the southern Congo craton, Namibia. To test the significance of this acidification event and reconstruct Earth's global seawater pH states at the Cryogenian-Ediacaran transition, we present a new boron isotope data set recorded in cap carbonates deposited on the Yangtze Platform in south China and on the Karatau microcontinent in Kazakhstan. Our compiled δ11B data reveal similar ocean pH patterns for all investigated cratons and confirm the presence of a global and synchronous ocean acidification event during the Marinoan deglacial period, compatible with elevated postglacial pCO2 concentrations. Differences in the details of the ocean acidification event point to regional distinctions in the buffering capacity of Ediacaran seawater.

Great Barrier Reef Calcification dropped 40% Over 35 Years due to Climate Change, Ocean Acidification

An expedition from the Hebrew University of Jerusalem and the Carnegie Institute of Science has measured a roughly 40% reduction in the rate of calcium carbonate deposited in Australia's Great Barrier Reef in the last 35 years — a scenario that could damage the reef framework and endanger the entire coral ecosystem.

Coral reefs are the most ecologically diverse and productive ecosystem in the ocean, with rich and diverse communities of fish, corals and mollusks making them a major attraction for marine and underwater tourism. Producing almost 50% of the net annual calcium carbonate in the oceans, corals play an important role in the global carbon cycle.

The ecological success of coral reefs depends on their calcium carbonate (CaCO3, limestone) structures that function as a huge filter to obtain plankton from the open ocean. Yet recent environmental changes including coastal nutrient pollution, global warming and ocean acidification caused by atmospheric CO2 increasingly threaten the existence of these unique ecosystems.

To better understand the effect of acidification on coral growth decline, Hebrew University scientists led by Prof. Jonathan Erez and Prof. Boaz Lazar at the Fredy and Nadine Herrmann Institute of Earth Sciences, together with Carnegie Institute colleagues Dr. J. Silverman and Dr. K. Caldeira, carried out a community metabolism study in Lizard Island at the Great Barrier Reef in Australia.

The researchers compared calcification rates documented in 2008 and 2009 to those measured using similar techniques in 1975-6. Despite the fact that the coral cover remained similar, the researchers found that the recent calcification rates had decreased by between 27% and 49%. These lower rates are consistent with predictions that took into account the increase in CO2 between the two periods, suggesting that ocean acidification is the main cause for the lower calcification rate at Lizard Island. The prediction of how coral reef communities should respond to ocean acidification comes from work conducted by Dr. Silverman for his PhD at the Hebrew University, with Dr. Lazar and Prof. Erez as his advisers.

While previous studies on individual reef building corals have shown that they lower their calcification rates in response to ocean acidification, in the present study this was demonstrated for the whole community. These findings suggest that coral reefs are now making skeletons that are less dense and more fragile. While they still look the same, these coral reefs are less able to resist physical and biological erosion.

link.

Evidence Ocean Acidification was Important to the Triassic-Jurassic Mass Extinction

The end-Triassic negative δ13C excursion: A lithologic test

Authors:

Bachan et al

Abstract:

The end-Triassic mass extinction is associated with a large negative carbon isotope excursion, which has been interpreted as reflecting the rapid injection of 13C depleted CO2 or methane associated with the emplacement of the Central Atlantic Magmatic Province. However, in a number of sections in central Europe, the negative excursion is associated with a carbonate-poor lithology, and the most isotopically depleted values are associated with the lowest percent carbonate, raising the possibility of a lithologic control on δ13Ccarb.

Here we test the uniqueness of the relationship between the carbonate-poor lithology and the δ13C signal by comparing the geochemistry of the extinction marl with two Upper Triassic carbonate-poor beds from lower positions within the same stratigraphic sections. We find that the extinction and non-extinction marls overlap nearly completely in terms of their carbonate content, but differ substantially in their isotopic trends. The extinction marl sections show strong depletions in the δ13C and δ18O of carbonate, and enrichment in δ13C of bulk organic carbon, while the non-extinction marls show almost no change in these metrics. Accordingly, the difference in isotopic content must lie in differences inherent to the beds themselves and the circumstances of their deposition and early diagenesis. Although a range of primary drivers for the isotopic trends is possible, an acidification origin for the marl, and oceanic origin for the carbon isotope excursion in carbonate are compatible with our data and supported by the broader context of the extinction.

Many Pacific Corals, Other Calcifiers Can Survive Ocean Acidification

Pacific-wide contrast highlights resistance of reef calcifiers to ocean acidification

Authors:

Comeau et al

Abstract:

Ocean acidification (OA) and its associated decline in calcium carbonate saturation states is one of the major threats that tropical coral reefs face this century. Previous studies of the effect of OA on coral reef calcifiers have described a wide variety of outcomes for studies using comparable partial pressure of CO2 (pCO2) ranges, suggesting that key questions remain unresolved. One unresolved hypothesis posits that heterogeneity in the response of reef calcifiers to high pCO2 is a result of regional-scale variation in the responses to OA. To test this hypothesis, we incubated two coral taxa (Pocillopora damicornis and massive Porites) and two calcified algae (Porolithon onkodes and Halimeda macroloba) under 400, 700 and 1000 μatm pCO2 levels in experiments in Moorea (French Polynesia), Hawaii (USA) and Okinawa (Japan), where environmental conditions differ. Both corals and H. macroloba were insensitive to OA at all three locations, while the effects of OA on P. onkodes were location-specific. In Moorea and Hawaii, calcification of P. onkodes was depressed by high pCO2, but for specimens in Okinawa, there was no effect of OA. Using a study of large geographical scale, we show that resistance to OA of some reef species is a constitutive character expressed across the Pacific.

Rapid and Sustained Surface Ocean Acidifcation During the Paleocene-Eocene Thermal Maximum?

Rapid and sustained surface ocean acidification during the Paleocene-Eocene Thermal Maximum

Authors:

Penman et al

Abstract:

The Paleocene-Eocene Thermal Maximum (PETM) has been associated with the release of several thousands of petagrams of carbon (Pg C) as methane and/or carbon dioxide into the ocean-atmosphere system within ~10 thousand years (ky), on the basis of the co-occurrence of a carbon isotope excursion (CIE), widespread dissolution of deep sea carbonates, and global warming. In theory, this rapid carbon release should have severely acidified the surface ocean, though no geochemical evidence has yet been presented. Using boron-based proxies for surface-ocean carbonate chemistry, we present the first observational evidence for a drop in the pH of surface and thermocline seawater during the PETM. Planktic foraminifers from a drill site in the North Pacific (ODP Site 1209) show a ~0.8‰ decrease in boron isotopic composition (δ11B) at the onset of the event, along with a 30-40% reduction in shell B/Ca. Similar trends in δ11B are present in two lower resolution records from the South Atlantic and Equatorial Pacific. These observations are consistent with significant, global acidification of the surface ocean lasting at least 70 ky and requiring sustained carbon release. The anomalies in the B records are consistent with an initial surface pH drop of ~0.3 units, at the upper range of model-based estimates of acidification.

Was Acid Rain the Kill Mechanism of the KT/K-Pg Extinction Brought on by the Chicxulub Impact?

Production of sulphate-rich vapour during the Chicxulub impact and implications for ocean acidification

Authors:

Ohno et al

Abstract:

The mass extinction event at the Cretaceous/Palaeogene boundary 65.5 Myr ago has been widely attributed to the Chicxulub impact, but the mechanisms of extinction remain debated. In the oceans, near-surface planktonic foraminifera suffered severe declines, in contrast to the relatively high survival rates of bottom-dwelling benthic foraminifera. The vapour produced by an impact into Chicxulub’s target rocks, which include sulphate-rich anhydrite, could have led to global acid rain, which can explain the pattern of oceanic extinctions. However, it has been suggested that most of the sulphur in the target rocks would have been released as sulphur dioxide and would have stayed in the stratosphere for a long time. ere we show, from impact experiments into anhydrite at velocities exceeding 10 km s−1, that sulphur trioxide dominates over sulphur dioxide in the resulting vapour cloud. Our experiments suggest that the Chicxulub impact released a huge quantity of sulphur trioxide into the atmosphere, where it would have rapidly combined with water vapour to form sulphuric acid aerosol particles. We also find, using a theoretical model of aerosol coagulation following the Chicxulub impact, that larger silicate particles ejected during the impact efficiently scavenge sulphuric acid aerosol particles and deliver the sulphuric acid to the surface within a few days. The rapid surface deposition of sulphuric acid would cause severe ocean acidification and account for preferential extinction of planktonic over benthic foraminifera.

Livermore and UC Santa Cruz Develop Carbon Sequestration Technique In Lab Which Helps De-Acidify Ocean Water

Lawrence Livermore scientists have discovered and demonstrated a new technique to remove and store atmospheric carbon dioxide while generating carbon-negative hydrogen and producing alkalinity, which can be used to offset ocean acidification.

The team demonstrated, at a laboratory scale, a system that uses the acidity normally produced in saline water electrolysis to accelerate silicate mineral dissolution while producing hydrogen fuel and other gases. The resulting electrolyte solution was shown to be significantly elevated in hydroxide concentration that in turn proved strongly absorptive and retentive of atmospheric CO2.

Further, the researchers suggest that the carbonate and bicarbonate produced in the process could be used to mitigate ongoing ocean acidification, similar to how an Alka Seltzer neutralizes excess acid in the stomach.

"We not only found a way to remove and store carbon dioxide from the atmosphere while producing valuable H2, we also suggest that we can help save marine ecosystems with this new technique," said Greg Rau, an LLNL visiting scientist, senior scientist at UC Santa Cruz and lead author of a paper appearing this week (May 27) in the Proceedings of the National Academy of Sciences.

When carbon dioxide is released into the atmosphere, a significant fraction is passively taken up by the ocean forming carbonic acid that makes the ocean more acidic. This acidification has been shown to be harmful to many species of marine life, especially corals and shellfish. By the middle of this century, the globe will likely warm by at least 2 degrees Celsius and the oceans will experience a more than 60 percent increase in acidity relative to pre-industrial levels. The alkaline solution generated by the new process could be added to the ocean to help neutralize this acid and help offset its effects on marine biota. However, further research is needed, the authors said.

"When powered by renewable electricity and consuming globally abundant minerals and saline solutions, such systems at scale might provide a relatively efficient, high-capacity means to consume and store excess atmospheric CO2 as environmentally beneficial seawater bicarbonate or carbonate," Rau said. "But the process also would produce a carbon-negative 'super green' fuel or chemical feedstock in the form of hydrogen."

Most previously described chemical methods of atmospheric carbon dioxide capture and storage are costly, using thermal/mechanical procedures to concentrate molecular CO2 from the air while recycling reagents, a process that is cumbersome, inefficient and expensive.

"Our process avoids most of these issues by not requiring CO2 to be concentrated from air and stored in a molecular form, pointing the way to more cost-effective, environmentally beneficial, and safer air CO2 management with added benefits of renewable hydrogen fuel production and ocean alkalinity addition," Rau said.

Interesting.  Will it scale and deal with real world scenarios?  It almost sounds too good to be true...

Many Shelled Animals Respond Unexpectedly to Raised Carbon Dioxide Levels

In a striking finding that raises new questions about carbon dioxide's (CO2) impact on marine life, Woods Hole Oceanographic Institution (WHOI) scientists report that some shell-building creatures—such as crabs, shrimp and lobsters—unexpectedly build more shell when exposed to ocean acidification caused by elevated levels of atmospheric carbon dioxide (CO2).

Because excess CO2 dissolves in the ocean—causing it to "acidify" —researchers have been concerned about the ability of certain organisms to maintain the strength of their shells. Carbon dioxide is known to trigger a process that reduces the abundance of carbonate ions in seawater—one of the primary materials that marine organisms use to build their calcium carbonate shells and skeletons.

The concern is that this process will trigger a weakening and decline in the shells of some species and, in the long term, upset the balance of the ocean ecosystem.

But in a study published in the Dec. 1 issue of Geology, a team led by former WHOI postdoctoral researcher Justin B. Ries found that seven of the 18 shelled species they observed actually built more shell when exposed to varying levels of increased acidification. This may be because the total amount of dissolved inorganic carbon available to them is actually increased when the ocean becomes more acidic, even though the concentration of carbonate ions is decreased.

"Most likely the organisms that responded positively were somehow able to manipulate…dissolved inorganic carbon in the fluid from which they precipitated their skeleton in a way that was beneficial to them," said Ries, now an assistant professor in marine sciences at the University of North Carolina. "They were somehow able to manipulate CO2…to build their skeletons."

Organisms displaying such improvement also included calcifying red and green algae, limpets and temperate urchins. Mussels showed no effect.

"We were surprised that some organisms didn't behave in the way we expected under elevated CO2," said Anne L. Cohen, a research specialist at WHOI and one of the study's co-authors. "What was really interesting was that some of the creatures, the coral, the hard clam and the lobster, for example, didn't seem to care about CO2 until it was higher than about 1,000 parts per million [ppm]." Current atmospheric CO2 levels are about 380 ppm, she said. Above this level, calcification was reduced in the coral and the hard clam, but elevated in the lobster

The "take-home message, " says Cohen, is that "we can't assume that elevated CO2 causes a proportionate decline in calcification of all calcifying organisms." WHOI and the National Science Foundation funded the work.

Conversely, some organisms—such as the soft clam and the oyster—showed a clear reduction in calcification in proportion to increases in CO2. In the most extreme finding, Ries, Cohen and WHOI Associate Scientist Daniel C. McCorkle exposed creatures to CO2 levels more than seven times the current level.

This led to the dissolving of aragonite—the form of calcium carbonate produced by corals and some other marine calcifiers. Under such exposure, hard and soft clams, conchs, periwinkles, whelks and tropical urchins began to lose their shells. "If this dissolution process continued for sufficient time, then these organisms could lose their shell completely," he said, "rendering them defenseless to predators."

"Some organisms were very sensitive," Cohen said, "some that have commercial value. But there were a couple that didn't respond to CO2 or didn't respond till it was sky-high—about 2,800 parts per million. We're not expecting to see that [CO2 level] anytime soon."

The researchers caution, however, that the findings—and acidification's overall impact—may be more complex than it appears. For example, Cohen says that available food and nutrients such as nitrates, phosphates and iron may help dictate how some organisms respond to carbon dioxide.

"We know that nutrients can be very important," she says. "We have found that corals for example, that have plenty of food and nutrients can be less sensitive" to CO2. "In this study, the organisms were well fed and we didn't constrain the nutrient levels.

"I wouldn't make any predictions based on these results. What these results indicate to us is that the organism response to elevated CO2 levels is complex and we now need to go back and study each organism in detail."

Let me second the endorsement of the idea that more study needs to be done.

However, based on past levels of CO2 content in the atmosphere, in Deep Time such as the Eocene, that all shelly animals would get whacked seemed...a little more apocalyptic than based in reality. To me. However, those were generally different species and genera than what's here now. But on the other hand, that the idea that all shelled mollusks, etc. would disappear seemed rather unlikely.