scholarly journals Capturing the global signature of surface ocean acidification during the Palaeocene–Eocene Thermal Maximum

2018 ◽  
Vol 376 (2130) ◽  
pp. 20170072 ◽  
Author(s):  
Tali L. Babila ◽  
Donald E. Penman ◽  
Bärbel Hönisch ◽  
D. Clay Kelly ◽  
Timothy J. Bralower ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Carbon Isotope ◽  
Atmospheric Carbon Dioxide ◽  
Environmental Changes ◽  
Planktonic Foraminifera ◽  
Tight Coupling ◽  
Carbonate Chemistry ◽  
Surface Ocean ◽  
Thermal Maximum ◽  
Carbon Release

Geologically abrupt carbon perturbations such as the Palaeocene–Eocene Thermal Maximum (PETM, approx. 56 Ma) are the closest geological points of comparison to current anthropogenic carbon emissions. Associated with the rapid carbon release during this event are profound environmental changes in the oceans including warming, deoxygenation and acidification. To evaluate the global extent of surface ocean acidification during the PETM, we present a compilation of new and published surface ocean carbonate chemistry and pH reconstructions from various palaeoceanographic settings. We use boron to calcium ratios (B/Ca) and boron isotopes (δ 11 B) in surface- and thermocline-dwelling planktonic foraminifera to reconstruct ocean carbonate chemistry and pH. Our records exhibit a B/Ca reduction of 30–40% and a δ 11 B decline of 1.0–1.2‰ coeval with the carbon isotope excursion. The tight coupling between boron proxies and carbon isotope records is consistent with the interpretation that oceanic absorption of the carbon released at the onset of the PETM resulted in widespread surface ocean acidification. The remarkable similarity among records from different ocean regions suggests that the degree of ocean carbonate change was globally near uniform. We attribute the global extent of surface ocean acidification to elevated atmospheric carbon dioxide levels during the main phase of the PETM. This article is part of a discussion meeting issue ‘Hyperthermals: rapid and extreme global warming in our geological past’.

scholarly journals The role of ocean acidification in <i>Emiliania huxleyi</i> coccolith thinning in the Mediterranean Sea

2014 ◽  
Vol 11 (10) ◽  
pp. 2857-2869 ◽  
Author(s):  
K. J. S. Meier ◽  
L. Beaufort ◽  
S. Heussner ◽  
P. Ziveri
Keyword(s):  
Ocean Acidification ◽  
Mediterranean Sea ◽  
Abundant Species ◽  
Emiliania Huxleyi ◽  
Carbonate Chemistry ◽  
Carbonate Production ◽  
Surface Ocean ◽  
Nw Mediterranean ◽  
Seawater Carbonate Chemistry

Abstract. Ocean acidification is a result of the uptake of anthropogenic CO2 from the atmosphere into the ocean and has been identified as a major environmental and economic threat. The release of several thousands of petagrams of carbon over a few hundred years will have an overwhelming effect on surface ocean carbon reservoirs. The recorded and anticipated changes in seawater carbonate chemistry will presumably affect global oceanic carbonate production. Coccolithophores as the primary calcifying phytoplankton group, and especially Emiliania huxleyi as the most abundant species have shown a reduction of calcification at increased CO2 concentrations for the majority of strains tested in culture experiments. A reduction of calcification is associated with a decrease in coccolith weight. However, the effect in monoclonal cultures is relatively small compared to the strong variability displayed in natural E. huxleyi communities, as these are a mix of genetically and sometimes morphologically distinct types. Average coccolith weight is likely influenced by the variability in seawater carbonate chemistry in different parts of the world's oceans and on glacial/interglacial time scales due to both physiological effects and morphotype selectivity. An effect of the ongoing ocean acidification on E. huxleyi calcification has so far not been documented in situ. Here, we analyze E. huxleyi coccolith weight from the NW Mediterranean Sea in a 12-year sediment trap series, and surface sediment and sediment core samples using an automated recognition and analyzing software. Our findings clearly show (1) a continuous decrease in the average coccolith weight of E. huxleyi from 1993 to 2005, reaching levels below pre-industrial (Holocene) and industrial (20th century) values recorded in the sedimentary record and (2) seasonal variability in coccolith weight that is linked to the coccolithophore productivity. The observed long-term decrease in coccolith weight is most likely a result of the changes in the surface ocean carbonate system. Our results provide the first indications of an in situ impact of ocean acidification on coccolithophore weight in a natural E. huxleyi population, even in the highly alkaline Mediterranean Sea.

scholarly journals The other ocean acidification problem: CO 2 as a resource among competitors for ecosystem dominance

2013 ◽  
Vol 368 (1627) ◽  
pp. 20120442 ◽  
Author(s):  
Sean D. Connell ◽  
Kristy J. Kroeker ◽  
Katharina E. Fabricius ◽  
David I. Kline ◽  
Bayden D. Russell
Keyword(s):  
Coral Reefs ◽  
Ocean Acidification ◽  
Atmospheric Carbon Dioxide ◽  
Environmental Changes ◽  
Kelp Forests ◽  
Direct Effects ◽  
Species Dominance ◽  
Tropical Conditions ◽  
Near Future

Predictions concerning the consequences of the oceanic uptake of increasing atmospheric carbon dioxide (CO 2 ) have been primarily occupied with the effects of ocean acidification on calcifying organisms, particularly those critical to the formation of habitats (e.g. coral reefs) or their maintenance (e.g. grazing echinoderms). This focus overlooks direct and indirect effects of CO 2 on non-calcareous taxa that play critical roles in ecosystem shifts (e.g. competitors). We present the model that future atmospheric [CO 2 ] may act as a resource for mat-forming algae, a diverse and widespread group known to reduce the resilience of kelp forests and coral reefs. We test this hypothesis by combining laboratory and field CO 2 experiments and data from ‘natural’ volcanic CO 2 vents. We show that mats have enhanced productivity in experiments and more expansive covers in situ under projected near-future CO 2 conditions both in temperate and tropical conditions. The benefits of CO 2 are likely to vary among species of producers, potentially leading to shifts in species dominance in a high CO 2 world. We explore how ocean acidification combines with other environmental changes across a number of scales, and raise awareness of CO 2 as a resource whose change in availability could have wide-ranging community consequences beyond its direct effects.

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

2014 ◽  
Vol 29 (5) ◽  
pp. 357-369 ◽  
Author(s):  
Donald E. Penman ◽  
Bärbel Hönisch ◽  
Richard E. Zeebe ◽  
Ellen Thomas ◽  
James C. Zachos
Keyword(s):  
Ocean Acidification ◽  
Surface Ocean ◽  
Thermal Maximum

scholarly journals Technical Note: A minimally invasive experimental system for <i>p</i>CO<sub>2</sub> manipulation in plankton cultures using passive gas exchange (atmospheric carbon control simulator)

2017 ◽  
Vol 14 (10) ◽  
pp. 2675-2684 ◽  
Author(s):  
Brooke A. Love ◽  
M. Brady Olson ◽  
Tristen Wuori
Keyword(s):  
Gas Exchange ◽  
Ocean Acidification ◽  
Environmental Changes ◽  
Technical Note ◽  
Time Interval ◽  
Gas Mixing ◽  
Carbonate Chemistry ◽  
Culture Methods ◽  
Atmospheric Carbon ◽  
Carbon Control

Abstract. As research into the biotic effects of ocean acidification has increased, the methods for simulating these environmental changes in the laboratory have multiplied. Here we describe the atmospheric carbon control simulator (ACCS) for the maintenance of plankton under controlled pCO2 conditions, designed for species sensitive to the physical disturbance introduced by the bubbling of cultures and for studies involving trophic interaction. The system consists of gas mixing and equilibration components coupled with large-volume atmospheric simulation chambers. These chambers allow gas exchange to counteract the changes in carbonate chemistry induced by the metabolic activity of the organisms. The system is relatively low cost, very flexible, and when used in conjunction with semi-continuous culture methods, it increases the density of organisms kept under realistic conditions, increases the allowable time interval between dilutions, and/or decreases the metabolically driven change in carbonate chemistry during these intervals. It accommodates a large number of culture vessels, which facilitate multi-trophic level studies and allow the tracking of variable responses within and across plankton populations to ocean acidification. It also includes components that increase the reliability of gas mixing systems using mass flow controllers.

scholarly journals Archaeal lipid biomarker constraints on the Paleocene-Eocene carbon isotope excursion

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Felix J. Elling ◽  
Julia Gottschalk ◽  
Katiana D. Doeana ◽  
Stephanie Kusch ◽  
Sarah J. Hurley ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Carbon Isotope ◽  
Carbon Emissions ◽  
Membrane Lipids ◽  
Geothermal Heating ◽  
Surface Ocean ◽  
Carbon Isotope Excursion ◽  
Thermal Maximum ◽  
Lipid Biomarker ◽  
Carbon Reservoir

Abstract A negative carbon isotope excursion recorded in terrestrial and marine archives reflects massive carbon emissions into the exogenic carbon reservoir during the Paleocene-Eocene Thermal Maximum. Yet, discrepancies in carbon isotope excursion estimates from different sample types lead to substantial uncertainties in the source, scale, and timing of carbon emissions. Here we show that membrane lipids of marine planktonic archaea reliably record both the carbon isotope excursion and surface ocean warming during the Paleocene-Eocene Thermal Maximum. Novel records of the isotopic composition of crenarchaeol constrain the global carbon isotope excursion magnitude to −4.0 ± 0.4‰, consistent with emission of >3000 Pg C from methane hydrate dissociation or >4400 Pg C for scenarios involving emissions from geothermal heating or oxidation of sedimentary organic matter. A pre-onset excursion in the isotopic composition of crenarchaeol and ocean temperature highlights the susceptibility of the late Paleocene carbon cycle to perturbations and suggests that climate instability preceded the Paleocene-Eocene Thermal Maximum.

scholarly journals The seawater carbon inventory at the Paleocene–Eocene Thermal Maximum

2020 ◽  
Vol 117 (39) ◽  
pp. 24088-24095
Author(s):  
Laura L. Haynes ◽  
Bärbel Hönisch
Keyword(s):  
Carbon Source ◽  
Dissolved Inorganic Carbon ◽  
Planktic Foraminifera ◽  
Natural Analog ◽  
Surface Ocean ◽  
Thermal Maximum ◽  
Carbon Release ◽  
Main Carbon Source ◽  
Carbon Inventory ◽  
Main Carbon

The Paleocene–Eocene Thermal Maximum (PETM) (55.6 Mya) was a geologically rapid carbon-release event that is considered the closest natural analog to anthropogenic CO2 emissions. Recent work has used boron-based proxies in planktic foraminifera to characterize the extent of surface-ocean acidification that occurred during the event. However, seawater acidity alone provides an incomplete constraint on the nature and source of carbon release. Here, we apply previously undescribed culture calibrations for the B/Ca proxy in planktic foraminifera and use them to calculate relative changes in seawater-dissolved inorganic carbon (DIC) concentration, surmising that Pacific surface-ocean DIC increased by +1,010−646+1,415 µmol/kg during the peak-PETM. Making reasonable assumptions for the pre-PETM oceanic DIC inventory, we provide a fully data-driven estimate of the PETM carbon source. Our reconstruction yields a mean source carbon δ13C of −10‰ and a mean increase in the oceanic C inventory of +14,900 petagrams of carbon (PgC), pointing to volcanic CO2 emissions as the main carbon source responsible for PETM warming.

scholarly journals Multiple early Eocene carbon isotope excursions associated with environmental changes in the Dieppe-Hampshire Basin (NW Europe)

2020 ◽  
Vol 191 ◽  
pp. 33
Author(s):  
Sylvain Garel ◽  
Christian Dupuis ◽  
Florence Quesnel ◽  
Jérémy Jacob ◽  
Johan Yans ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Environmental Changes ◽  
Climatic Changes ◽  
Coastal Sediments ◽  
Carbonate Dissolution ◽  
Early Eocene ◽  
Higher Plant ◽  
Carbon Isotopic ◽  
Paleoclimatic Changes ◽  
Thermal Maximum

The early Eocene experienced a series of short-lived global warming events, known as hyperthermals, associated with negative carbon isotope excursions (CIE). The Paleocene-Eocene Thermal Maximum (PETM or ETM-1) and Eocene Thermal Maximum 2 (ETM-2) are the two main events of this Epoch, both marked by massive sea-floor carbonate dissolution. Their timing, amplitude and impacts are rather well documented, but CIEs with lower amplitudes also associated with carbonate dissolution are still poorly studied (e.g. events E1 to H1), especially in the terrestrial realm where hiatus/disconformities and various sedimentary rates in a single succession may complicate the assignation to global isotopic events. Here we present a new high-resolution multi-proxy study on the terrestrial, lagoonal and shallow marine late Paleocene-early Eocene succession from two sites of the Cap d’Ailly area in the Dieppe-Hampshire Basin (Normandy, France). Carbon isotope data (δ13C) on bulk organic matter and higher-plant derived n-alkanes, and K-Ar ages on authigenic glauconite were determined to provide a stratigraphic framework. Palynofacies, distribution and hydrogen isotope values (δ2H) of higher-plant derived n-alkanes allowed us to unravel paleoenvironmental and paleoclimatic changes. In coastal sediments of the Cap d’Ailly area, δ13C values revealed two main negative CIEs, from base to top CIE1 and CIE2, and 3 less pronounced negative excursions older than the NP11 nannofossil biozone. While the CIE1 is clearly linked with the PETM initiation, the CIE2 could either correspond to 1) a second excursion within the PETM interval caused by strong local environmental changes or 2) a global carbon isotopic event that occurred between the PETM and ETM-2. Paleoenvironmental data indicated that both main CIEs were associated with dramatic changes such as eutrophication, algal and/or dinoflagellate blooms along with paleohydrological variations and an increase in seasonality. They revealed that the intervals immediately below these CIEs are also marked by environmental and climatic changes. Thus, this study shows either 1) a PETM marked by at least two distinct intervals of strong environmental and climatic changes or 2) at least one “minor” CIE: E1, E2, F or G, was associated with strong environmental and climatic changes similar to those that occurred during the PETM.

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