Articles | Volume 13, issue 13
https://doi.org/10.5194/bg-13-3901-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Special issue:
https://doi.org/10.5194/bg-13-3901-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Research article
| 
07 Jul 2016
Research article |
| 07 Jul 2016
No observed effect of ocean acidification on nitrogen biogeochemistry in a summer Baltic Sea plankton community
GEOMAR Helmholtz Centre for Ocean Research Kiel,
Düsternbrooker Weg 20, 24105 Kiel, Germany
Eric P. Achterberg
GEOMAR Helmholtz Centre for Ocean Research Kiel,
Düsternbrooker Weg 20, 24105 Kiel, Germany
National Oceanography Centre Southampton, European Way,
University of Southampton, Southampton, SO14 3ZH, UK
Lennart T. Bach
GEOMAR Helmholtz Centre for Ocean Research Kiel,
Düsternbrooker Weg 20, 24105 Kiel, Germany
Tim Boxhammer
GEOMAR Helmholtz Centre for Ocean Research Kiel,
Düsternbrooker Weg 20, 24105 Kiel, Germany
Jan Czerny
GEOMAR Helmholtz Centre for Ocean Research Kiel,
Düsternbrooker Weg 20, 24105 Kiel, Germany
Mathias Haunost
GEOMAR Helmholtz Centre for Ocean Research Kiel,
Düsternbrooker Weg 20, 24105 Kiel, Germany
Kai-Georg Schulz
GEOMAR Helmholtz Centre for Ocean Research Kiel,
Düsternbrooker Weg 20, 24105 Kiel, Germany
Southern Cross University, Military Road, East Lismore,
NSW 2480, Australia
Annegret Stuhr
GEOMAR Helmholtz Centre for Ocean Research Kiel,
Düsternbrooker Weg 20, 24105 Kiel, Germany
Ulf Riebesell
GEOMAR Helmholtz Centre for Ocean Research Kiel,
Düsternbrooker Weg 20, 24105 Kiel, Germany
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Jiaying A. Guo, Robert F. Strzepek, Kerrie M. Swadling, Ashley T. Townsend, and Lennart T. Bach
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Ocean alkalinity enhancement aims to increase atmospheric CO2 sequestration by adding alkaline materials to the ocean. We assessed the environmental effects of olivine and steel slag powder on coastal plankton. Overall, slag is more efficient than olivine in releasing total alkalinity and, thus, in its ability to sequester CO2. Slag also had less environmental effect on the enclosed plankton communities when considering its higher CO2 removal potential based on this 3-week experiment.
Librada Ramírez, Leonardo J. Pozzo-Pirotta, Aja Trebec, Víctor Manzanares-Vázquez, José L. Díez, Javier Arístegui, Ulf Riebesell, Stephen D. Archer, and María Segovia
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We studied the potential effects of increasing ocean alkalinity on a natural plankton community in subtropical waters of the Atlantic near Gran Canaria, Spain. Alkalinity is the capacity of water to resist acidification and plankton are usually microscopic plants (phytoplankton) and animals (zooplankton), often less than 2,5 cm in length. This study suggests that increasing ocean alkalinity did not have a significant negative impact on the studied plankton community.
Allanah Joy Paul, Mathias Haunost, Silvan Urs Goldenberg, Jens Hartmann, Nicolás Sánchez, Julieta Schneider, Niels Suitner, and Ulf Riebesell
EGUsphere, https://doi.org/10.5194/egusphere-2024-417, https://doi.org/10.5194/egusphere-2024-417, 2024
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Xiaoke Xin, Giulia Faucher, and Ulf Riebesell
Biogeosciences, 21, 761–772, https://doi.org/10.5194/bg-21-761-2024, https://doi.org/10.5194/bg-21-761-2024, 2024
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Ocean alkalinity enhancement (OAE) is a promising approach to remove CO2 by accelerating natural rock weathering. However, some of the alkaline substances contain trace metals which could be toxic to marine life. By exposing three representative phytoplankton species to Ni released from alkaline materials, we observed varying responses of phytoplankton to nickel concentrations, suggesting caution should be taken and toxic thresholds should be avoided in OAE with Ni-rich materials.
Lennart Thomas Bach
Biogeosciences, 21, 261–277, https://doi.org/10.5194/bg-21-261-2024, https://doi.org/10.5194/bg-21-261-2024, 2024
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Ocean alkalinity enhancement (OAE) is a widely considered marine carbon dioxide removal method. OAE aims to accelerate chemical rock weathering, which is a natural process that slowly sequesters atmospheric carbon dioxide. This study shows that the addition of anthropogenic alkalinity via OAE can reduce the natural release of alkalinity and, therefore, reduce the efficiency of OAE for climate mitigation. However, the additionality problem could be mitigated via a variety of activities.
Jana Krause, Dustin Carroll, Juan Höfer, Jeremy Donaire, Eric Pieter Achterberg, Emilio Alarcón, Te Liu, Lorenz Meire, Kechen Zhu, and Mark James Hopwood
EGUsphere, https://doi.org/10.5194/egusphere-2023-2991, https://doi.org/10.5194/egusphere-2023-2991, 2024
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Icebergs are a mechanism via which the cryosphere and ocean interact. Here we analyzed ice samples from both Arctic and Antarctic polar regions to assess the variability in the composition of calved ice. Our results show that low concentrations of nitrate and phosphate in ice are primarily atmospheric in origin, whereas sediments impart a low concentration of silica and modest concentrations of trace metals, especially iron and manganese.
Philipp Suessle, Jan Taucher, Silvan Goldenberg, Moritz Baumann, Kristian Spilling, Andrea Noche-Ferreira, Mari Vanharanta, and Ulf Riebesell
EGUsphere, https://doi.org/10.5194/egusphere-2023-2800, https://doi.org/10.5194/egusphere-2023-2800, 2023
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Ocean alkalinity enhancement (OAE) is a negative emission technology which may alter marine communities and the particle export they drive. Here, impacts of carbonate-based OAE on the flux and attenuation of sinking particles in an oligotrophic plankton community are presented. Whilst biological parameters remained unaffected, abiotic carbonate precipitation occurred. Among counteracting OAE’s efficiency, it influenced mineral ballasting and particle sinking velocities, requiring monitoring.
David T. Ho, Laurent Bopp, Jaime B. Palter, Matthew C. Long, Philip W. Boyd, Griet Neukermans, and Lennart T. Bach
State Planet, 2-oae2023, 12, https://doi.org/10.5194/sp-2-oae2023-12-2023, https://doi.org/10.5194/sp-2-oae2023-12-2023, 2023
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Monitoring, reporting, and verification (MRV) refers to the multistep process to quantify the amount of carbon dioxide removed by a carbon dioxide removal (CDR) activity. Here, we make recommendations for MRV for Ocean Alkalinity Enhancement (OAE) research, arguing that it has an obligation for comprehensiveness, reproducibility, and transparency, as it may become the foundation for assessing large-scale deployment. Both observations and numerical simulations will be needed for MRV.
Tyler Cyronak, Rebecca Albright, and Lennart T. Bach
State Planet, 2-oae2023, 7, https://doi.org/10.5194/sp-2-oae2023-7-2023, https://doi.org/10.5194/sp-2-oae2023-7-2023, 2023
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Ocean alkalinity enhancement (OAE) is a marine carbon dioxide removal (CDR) approach. Publicly funded research projects have begun, and philanthropic funding and start-ups are collectively pushing the field forward. This rapid progress in research activities has created an urgent need to learn if and how OAE can work at scale. This chapter of the Guide to Best Practices in Ocean Alkalinity Enhancement Research focuses on field experiments.
Ulf Riebesell, Daniela Basso, Sonja Geilert, Andrew W. Dale, and Matthias Kreuzburg
State Planet, 2-oae2023, 6, https://doi.org/10.5194/sp-2-oae2023-6-2023, https://doi.org/10.5194/sp-2-oae2023-6-2023, 2023
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Mesocosm experiments represent a highly valuable tool in determining the safe operating space of ocean alkalinity enhancement (OAE) applications. By combining realism and biological complexity with controllability and replication, they provide an ideal OAE test bed and a critical stepping stone towards field applications. Mesocosm approaches can also be helpful in testing the efficacy, efficiency and permanence of OAE applications.
Kai G. Schulz, Lennart T. Bach, and Andrew G. Dickson
State Planet, 2-oae2023, 2, https://doi.org/10.5194/sp-2-oae2023-2-2023, https://doi.org/10.5194/sp-2-oae2023-2-2023, 2023
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Ocean alkalinity enhancement is a promising approach for long-term anthropogenic carbon dioxide sequestration, required to avoid catastrophic climate change. In this chapter we describe its impacts on seawater carbonate chemistry speciation and highlight pitfalls that need to be avoided during sampling, storage, measurements, and calculations.
Andreas Oschlies, Lennart T. Bach, Rosalind E. M. Rickaby, Terre Satterfield, Romany Webb, and Jean-Pierre Gattuso
State Planet, 2-oae2023, 1, https://doi.org/10.5194/sp-2-oae2023-1-2023, https://doi.org/10.5194/sp-2-oae2023-1-2023, 2023
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Reaching promised climate targets will require the deployment of carbon dioxide removal (CDR). Marine CDR options receive more and more interest. Based on idealized theoretical studies, ocean alkalinity enhancement (OAE) appears as a promising marine CDR method. We provide an overview on the current situation of developing OAE as a marine CDR method and describe the history that has led to the creation of the OAE research best practice guide.
Moritz Baumann, Allanah Joy Paul, Jan Taucher, Lennart Thomas Bach, Silvan Goldenberg, Paul Stange, Fabrizio Minutolo, and Ulf Riebesell
Biogeosciences, 20, 2595–2612, https://doi.org/10.5194/bg-20-2595-2023, https://doi.org/10.5194/bg-20-2595-2023, 2023
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The sinking velocity of marine particles affects how much atmospheric CO2 is stored inside our oceans. We measured particle sinking velocities in the Peruvian upwelling system and assessed their physical and biochemical drivers. We found that sinking velocity was mainly influenced by particle size and porosity, while ballasting minerals played only a minor role. Our findings help us to better understand the particle sinking dynamics in this highly productive marine system.
Kristian Spilling, Jonna Piiparinen, Eric P. Achterberg, Javier Arístegui, Lennart T. Bach, Maria T. Camarena-Gómez, Elisabeth von der Esch, Martin A. Fischer, Markel Gómez-Letona, Nauzet Hernández-Hernández, Judith Meyer, Ruth A. Schmitz, and Ulf Riebesell
Biogeosciences, 20, 1605–1619, https://doi.org/10.5194/bg-20-1605-2023, https://doi.org/10.5194/bg-20-1605-2023, 2023
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We carried out an enclosure experiment using surface water off Peru with different additions of oxygen minimum zone water. In this paper, we report on enzyme activity and provide data on the decomposition of organic matter. We found very high activity with respect to an enzyme breaking down protein, suggesting that this is important for nutrient recycling both at present and in the future ocean.
Markus A. Min, David M. Needham, Sebastian Sudek, Nathan Kobun Truelove, Kathleen J. Pitz, Gabriela M. Chavez, Camille Poirier, Bente Gardeler, Elisabeth von der Esch, Andrea Ludwig, Ulf Riebesell, Alexandra Z. Worden, and Francisco P. Chavez
Biogeosciences, 20, 1277–1298, https://doi.org/10.5194/bg-20-1277-2023, https://doi.org/10.5194/bg-20-1277-2023, 2023
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Emerging molecular methods provide new ways of understanding how marine communities respond to changes in ocean conditions. Here, environmental DNA was used to track the temporal evolution of biological communities in the Peruvian coastal upwelling system and in an adjacent enclosure where upwelling was simulated. We found that the two communities quickly diverged, with the open ocean being one found during upwelling and the enclosure evolving to one found under stratified conditions.
Jens Hartmann, Niels Suitner, Carl Lim, Julieta Schneider, Laura Marín-Samper, Javier Arístegui, Phil Renforth, Jan Taucher, and Ulf Riebesell
Biogeosciences, 20, 781–802, https://doi.org/10.5194/bg-20-781-2023, https://doi.org/10.5194/bg-20-781-2023, 2023
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CO2 can be stored in the ocean via increasing alkalinity of ocean water. Alkalinity can be created via dissolution of alkaline materials, like limestone or soda. Presented research studies boundaries for increasing alkalinity in seawater. The best way to increase alkalinity was found using an equilibrated solution, for example as produced from reactors. Adding particles for dissolution into seawater on the other hand produces the risk of losing alkalinity and degassing of CO2 to the atmosphere.
Allanah Joy Paul, Lennart Thomas Bach, Javier Arístegui, Elisabeth von der Esch, Nauzet Hernández-Hernández, Jonna Piiparinen, Laura Ramajo, Kristian Spilling, and Ulf Riebesell
Biogeosciences, 19, 5911–5926, https://doi.org/10.5194/bg-19-5911-2022, https://doi.org/10.5194/bg-19-5911-2022, 2022
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We investigated how different deep water chemistry and biology modulate the response of surface phytoplankton communities to upwelling in the Peruvian coastal zone. Our results show that the most influential drivers were the ratio of inorganic nutrients (N : P) and the microbial community present in upwelling source water. These led to unexpected and variable development in the phytoplankton assemblage that could not be predicted by the amount of inorganic nutrients alone.
Aaron Ferderer, Zanna Chase, Fraser Kennedy, Kai G. Schulz, and Lennart T. Bach
Biogeosciences, 19, 5375–5399, https://doi.org/10.5194/bg-19-5375-2022, https://doi.org/10.5194/bg-19-5375-2022, 2022
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Ocean alkalinity enhancement has the capacity to remove vast quantities of carbon from the atmosphere, but its effect on marine ecosystems is largely unknown. We assessed the effect of increased alkalinity on a coastal phytoplankton community when seawater was equilibrated and not equilibrated with atmospheric CO2. We found that the phytoplankton community was moderately affected by increased alkalinity and equilibration with atmospheric CO2 had little influence on this effect.
Jiaying Abby Guo, Robert Strzepek, Anusuya Willis, Aaron Ferderer, and Lennart Thomas Bach
Biogeosciences, 19, 3683–3697, https://doi.org/10.5194/bg-19-3683-2022, https://doi.org/10.5194/bg-19-3683-2022, 2022
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Ocean alkalinity enhancement is a CO2 removal method with significant potential, but it can lead to a perturbation of the ocean with trace metals such as nickel. This study tested the effect of increasing nickel concentrations on phytoplankton growth and photosynthesis. We found that the response to nickel varied across the 11 phytoplankton species tested here, but the majority were rather insensitive. We note, however, that responses may be different under other experimental conditions.
Charly A. Moras, Lennart T. Bach, Tyler Cyronak, Renaud Joannes-Boyau, and Kai G. Schulz
Biogeosciences, 19, 3537–3557, https://doi.org/10.5194/bg-19-3537-2022, https://doi.org/10.5194/bg-19-3537-2022, 2022
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This research presents the first laboratory results of quick and hydrated lime dissolution in natural seawater. These two minerals are of great interest for ocean alkalinity enhancement, a strategy aiming to decrease atmospheric CO2 concentrations. Following the dissolution of these minerals, we identified several hurdles and presented ways to avoid them or completely negate them. Finally, we proceeded to various simulations in today’s oceans to implement the strategy at its highest potential.
Shao-Min Chen, Ulf Riebesell, Kai G. Schulz, Elisabeth von der Esch, Eric P. Achterberg, and Lennart T. Bach
Biogeosciences, 19, 295–312, https://doi.org/10.5194/bg-19-295-2022, https://doi.org/10.5194/bg-19-295-2022, 2022
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Oxygen minimum zones in the ocean are characterized by enhanced carbon dioxide (CO2) levels and are being further acidified by increasing anthropogenic atmospheric CO2. Here we report CO2 system measurements in a mesocosm study offshore Peru during a rare coastal El Niño event to investigate how CO2 dynamics may respond to ongoing ocean deoxygenation. Our observations show that nitrogen limitation, productivity, and plankton community shift play an important role in driving the CO2 dynamics.
Kai G. Schulz, Eric P. Achterberg, Javier Arístegui, Lennart T. Bach, Isabel Baños, Tim Boxhammer, Dirk Erler, Maricarmen Igarza, Verena Kalter, Andrea Ludwig, Carolin Löscher, Jana Meyer, Judith Meyer, Fabrizio Minutolo, Elisabeth von der Esch, Bess B. Ward, and Ulf Riebesell
Biogeosciences, 18, 4305–4320, https://doi.org/10.5194/bg-18-4305-2021, https://doi.org/10.5194/bg-18-4305-2021, 2021
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Upwelling of nutrient-rich deep waters to the surface make eastern boundary upwelling systems hot spots of marine productivity. This leads to subsurface oxygen depletion and the transformation of bioavailable nitrogen into inert N2. Here we quantify nitrogen loss processes following a simulated deep water upwelling. Denitrification was the dominant process, and budget calculations suggest that a significant portion of nitrogen that could be exported to depth is already lost in the surface ocean.
Neil J. Wyatt, Angela Milne, Eric P. Achterberg, Thomas J. Browning, Heather A. Bouman, E. Malcolm S. Woodward, and Maeve C. Lohan
Biogeosciences, 18, 4265–4280, https://doi.org/10.5194/bg-18-4265-2021, https://doi.org/10.5194/bg-18-4265-2021, 2021
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Using data collected during two expeditions to the South Atlantic Ocean, we investigated how the interaction between external sources and biological activity influenced the availability of the trace metals zinc and cobalt. This is important as both metals play essential roles in the metabolism and growth of phytoplankton and thus influence primary productivity of the oceans. We found seasonal changes in both processes that helped explain upper-ocean trace metal cycling.
Maximiliano J. Vergara-Jara, Mark J. Hopwood, Thomas J. Browning, Insa Rapp, Rodrigo Torres, Brian Reid, Eric P. Achterberg, and José Luis Iriarte
Ocean Sci., 17, 561–578, https://doi.org/10.5194/os-17-561-2021, https://doi.org/10.5194/os-17-561-2021, 2021
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Ash from the Calbuco 2015 eruption spread across northern Patagonia, the SE Pacific and the SW Atlantic. In the Pacific, a phytoplankton bloom corresponded closely to the volcanic ash plume, suggesting that ash fertilized this region of the ocean. No such fertilization was found in the Atlantic where nutrients plausibly supplied by ash were likely already in excess of phytoplankton demand. In Patagonia, the May bloom was more intense than usual, but the mechanistic link to ash was less clear.
Michelle N. Simone, Kai G. Schulz, Joanne M. Oakes, and Bradley D. Eyre
Biogeosciences, 18, 1823–1838, https://doi.org/10.5194/bg-18-1823-2021, https://doi.org/10.5194/bg-18-1823-2021, 2021
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Estuaries are responsible for a large contribution of dissolved organic carbon (DOC) to the global C cycle, but it is unknown how this will change in the future. DOC fluxes from unvegetated sediments were investigated ex situ subject to conditions of warming and ocean acidification. The future climate shifted sediment fluxes from a slight DOC source to a significant sink, with global coastal DOC export decreasing by 80 %. This has global implications for C cycling and long-term C storage.
Yu-Te Hsieh, Walter Geibert, E. Malcolm S. Woodward, Neil J. Wyatt, Maeve C. Lohan, Eric P. Achterberg, and Gideon M. Henderson
Biogeosciences, 18, 1645–1671, https://doi.org/10.5194/bg-18-1645-2021, https://doi.org/10.5194/bg-18-1645-2021, 2021
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The South Atlantic near 40° S is one of the high-productivity and most dynamic nutrient regions in the oceans, but the sources and fluxes of trace elements (TEs) to this region remain unclear. This study investigates seawater Ra-228 and provides important constraints on ocean mixing and dissolved TE fluxes to this region. Vertical mixing is a more important source than aeolian or shelf inputs in this region, but particulate or winter deep-mixing inputs may be required to balance the TE budgets.
Jan Lüdke, Marcus Dengler, Stefan Sommer, David Clemens, Sören Thomsen, Gerd Krahmann, Andrew W. Dale, Eric P. Achterberg, and Martin Visbeck
Ocean Sci., 16, 1347–1366, https://doi.org/10.5194/os-16-1347-2020, https://doi.org/10.5194/os-16-1347-2020, 2020
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We analyse the intraseasonal variability of the alongshore circulation off Peru in early 2017, this circulation is very important for the supply of nutrients to the upwelling regime. The causes of this variability and its impact on the biogeochemistry are investigated. The poleward flow is strengthened during the observed time period, likely by a downwelling coastal trapped wave. The stronger current causes an increase in nitrate and reduces the deficit of fixed nitrogen relative to phosphorus.
Ruifang C. Xie, Frédéric A. C. Le Moigne, Insa Rapp, Jan Lüdke, Beat Gasser, Marcus Dengler, Volker Liebetrau, and Eric P. Achterberg
Biogeosciences, 17, 4919–4936, https://doi.org/10.5194/bg-17-4919-2020, https://doi.org/10.5194/bg-17-4919-2020, 2020
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Thorium-234 (234Th) is widely used to study carbon fluxes from the surface ocean to depth. But few studies stress the relevance of oceanic advection and diffusion on the downward 234Th fluxes in nearshore environments. Our study in offshore Peru showed strong temporal variations in both the importance of physical processes on 234Th flux estimates and the oceanic residence time of 234Th, whereas salinity-derived seawater 238U activities accounted for up to 40 % errors in 234Th flux estimates.
Lennart Thomas Bach, Allanah Joy Paul, Tim Boxhammer, Elisabeth von der Esch, Michelle Graco, Kai Georg Schulz, Eric Achterberg, Paulina Aguayo, Javier Arístegui, Patrizia Ayón, Isabel Baños, Avy Bernales, Anne Sophie Boegeholz, Francisco Chavez, Gabriela Chavez, Shao-Min Chen, Kristin Doering, Alba Filella, Martin Fischer, Patricia Grasse, Mathias Haunost, Jan Hennke, Nauzet Hernández-Hernández, Mark Hopwood, Maricarmen Igarza, Verena Kalter, Leila Kittu, Peter Kohnert, Jesus Ledesma, Christian Lieberum, Silke Lischka, Carolin Löscher, Andrea Ludwig, Ursula Mendoza, Jana Meyer, Judith Meyer, Fabrizio Minutolo, Joaquin Ortiz Cortes, Jonna Piiparinen, Claudia Sforna, Kristian Spilling, Sonia Sanchez, Carsten Spisla, Michael Sswat, Mabel Zavala Moreira, and Ulf Riebesell
Biogeosciences, 17, 4831–4852, https://doi.org/10.5194/bg-17-4831-2020, https://doi.org/10.5194/bg-17-4831-2020, 2020
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The eastern boundary upwelling system off Peru is among Earth's most productive ocean ecosystems, but the factors that control its functioning are poorly constrained. Here we used mesocosms, moored ~ 6 km offshore Peru, to investigate how processes in plankton communities drive key biogeochemical processes. We show that nutrient and light co-limitation keep productivity and export at a remarkably constant level while stoichiometry changes strongly with shifts in plankton community structure.
Stacy Deppeler, Kai G. Schulz, Alyce Hancock, Penelope Pascoe, John McKinlay, and Andrew Davidson
Biogeosciences, 17, 4153–4171, https://doi.org/10.5194/bg-17-4153-2020, https://doi.org/10.5194/bg-17-4153-2020, 2020
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Our study showed how ocean acidification can exert both direct and indirect influences on the interactions among trophic levels within the microbial loop. Microbial grazer abundance was reduced at CO2 concentrations at and above 634 µatm, while microbial communities increased in abundance, likely due to a reduction in being grazed. Such changes in predator–prey interactions with ocean acidification could have significant effects on the food web and biogeochemistry in the Southern Ocean.
Anna Plass, Christian Schlosser, Stefan Sommer, Andrew W. Dale, Eric P. Achterberg, and Florian Scholz
Biogeosciences, 17, 3685–3704, https://doi.org/10.5194/bg-17-3685-2020, https://doi.org/10.5194/bg-17-3685-2020, 2020
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We compare the cycling of Fe and Cd in sulfidic sediments of the Peruvian oxygen minimum zone. Due to the contrasting solubility of their sulfide minerals, the sedimentary Fe release and Cd burial fluxes covary with spatial and temporal distributions of H2S. Depending on the solubility of their sulfide minerals, sedimentary trace metal fluxes will respond differently to ocean deoxygenation/expansion of H2S concentrations, which may change trace metal stoichiometry of upwelling water masses.
Giulia Faucher, Ulf Riebesell, and Lennart Thomas Bach
Clim. Past, 16, 1007–1025, https://doi.org/10.5194/cp-16-1007-2020, https://doi.org/10.5194/cp-16-1007-2020, 2020
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We designed five experiments choosing different coccolithophore species that have been evolutionarily distinct for millions of years. If all species showed the same morphological response to an environmental driver, this could be indicative of a response pattern that is conserved over geological timescales. We found an increase in the percentage of malformed coccoliths under altered CO2, providing evidence that this response could be used as paleo-proxy for episodes of acute CO2 perturbations.
Mark J. Hopwood, Dustin Carroll, Thorben Dunse, Andy Hodson, Johnna M. Holding, José L. Iriarte, Sofia Ribeiro, Eric P. Achterberg, Carolina Cantoni, Daniel F. Carlson, Melissa Chierici, Jennifer S. Clarke, Stefano Cozzi, Agneta Fransson, Thomas Juul-Pedersen, Mie H. S. Winding, and Lorenz Meire
The Cryosphere, 14, 1347–1383, https://doi.org/10.5194/tc-14-1347-2020, https://doi.org/10.5194/tc-14-1347-2020, 2020
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Here we compare and contrast results from five well-studied Arctic field sites in order to understand how glaciers affect marine biogeochemistry and marine primary production. The key questions are listed as follows. Where and when does glacial freshwater discharge promote or reduce marine primary production? How does spatio-temporal variability in glacial discharge affect marine primary production? And how far-reaching are the effects of glacial discharge on marine biogeochemistry?
Claudia Frey, Hermann W. Bange, Eric P. Achterberg, Amal Jayakumar, Carolin R. Löscher, Damian L. Arévalo-Martínez, Elizabeth León-Palmero, Mingshuang Sun, Xin Sun, Ruifang C. Xie, Sergey Oleynik, and Bess B. Ward
Biogeosciences, 17, 2263–2287, https://doi.org/10.5194/bg-17-2263-2020, https://doi.org/10.5194/bg-17-2263-2020, 2020
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The production of N2O via nitrification and denitrification associated with low-O2 waters is a major source of oceanic N2O. We investigated the regulation and dynamics of these processes with respect to O2 and organic matter inputs. The transcription of the key nitrification gene amoA rapidly responded to changes in O2 and strongly correlated with N2O production rates. N2O production by denitrification was clearly stimulated by organic carbon, implying that its supply controls N2O production.
Mark J. Hopwood, Nicolas Sanchez, Despo Polyviou, Øystein Leiknes, Julián Alberto Gallego-Urrea, Eric P. Achterberg, Murat V. Ardelan, Javier Aristegui, Lennart Bach, Sengul Besiktepe, Yohann Heriot, Ioanna Kalantzi, Tuba Terbıyık Kurt, Ioulia Santi, Tatiana M. Tsagaraki, and David Turner
Biogeosciences, 17, 1309–1326, https://doi.org/10.5194/bg-17-1309-2020, https://doi.org/10.5194/bg-17-1309-2020, 2020
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Hydrogen peroxide, H2O2, is formed naturally in sunlight-exposed water by photochemistry. At high concentrations it is undesirable to biological cells because it is a stressor. Here, across a range of incubation experiments in diverse marine environments (Gran Canaria, the Mediterranean, Patagonia and Svalbard), we determine that two factors consistently affect the H2O2 concentrations irrespective of geographical location: bacteria abundance and experiment design.
Mark J. Hopwood, Carolina Santana-González, Julian Gallego-Urrea, Nicolas Sanchez, Eric P. Achterberg, Murat V. Ardelan, Martha Gledhill, Melchor González-Dávila, Linn Hoffmann, Øystein Leiknes, Juana Magdalena Santana-Casiano, Tatiana M. Tsagaraki, and David Turner
Biogeosciences, 17, 1327–1342, https://doi.org/10.5194/bg-17-1327-2020, https://doi.org/10.5194/bg-17-1327-2020, 2020
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Fe is an essential micronutrient. Fe(III)-organic species are thought to account for > 99 % of dissolved Fe in seawater. Here we quantified Fe(II) during experiments in Svalbard, Gran Canaria, and Patagonia. Fe(II) was always a measurable fraction of dissolved Fe up to 65 %. Furthermore, when Fe(II) was allowed to decay in the dark, it remained present longer than predicted by kinetic equations, suggesting that Fe(II) is a more important fraction of dissolved Fe in seawater than widely recognized.
Insa Rapp, Christian Schlosser, Jan-Lukas Menzel Barraqueta, Bernhard Wenzel, Jan Lüdke, Jan Scholten, Beat Gasser, Patrick Reichert, Martha Gledhill, Marcus Dengler, and Eric P. Achterberg
Biogeosciences, 16, 4157–4182, https://doi.org/10.5194/bg-16-4157-2019, https://doi.org/10.5194/bg-16-4157-2019, 2019
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The availability of iron (Fe) affects phytoplankton growth in large parts of the ocean. Shelf sediments, particularly in oxygen minimum zones, are a major source of Fe and other essential micronutrients, such as cobalt (Co) and manganese (Mn). We observed enhanced concentrations of Fe, Co, and Mn corresponding with low oxygen concentrations along the Mauritanian shelf, indicating that the projected future decrease in oxygen concentrations may result in increases in Fe, Mn, and Co concentrations.
Lennart Thomas Bach and Jan Taucher
Ocean Sci., 15, 1159–1175, https://doi.org/10.5194/os-15-1159-2019, https://doi.org/10.5194/os-15-1159-2019, 2019
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Diatoms are a group of phytoplankton species responsible for ~ 25 % of primary production on Earth. Ocean acidification (OA) could influence diatoms but the key question is if they become more or less important within marine food webs. We synthesize OA experiments with natural communities and found that diatoms are more likely to be positively than negatively affected by high CO2 and larger species may profit in particular. This has important implications for ecosystem services diatoms provide.
Jan-Lukas Menzel Barraqueta, Jessica K. Klar, Martha Gledhill, Christian Schlosser, Rachel Shelley, Hélène F. Planquette, Bernhard Wenzel, Geraldine Sarthou, and Eric P. Achterberg
Biogeosciences, 16, 1525–1542, https://doi.org/10.5194/bg-16-1525-2019, https://doi.org/10.5194/bg-16-1525-2019, 2019
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We used surface water dissolved aluminium concentrations collected in four different GEOTRACES cruises to determine atmospheric deposition fluxes to the ocean. We calculate atmospheric deposition fluxes for largely under-sampled regions of the Atlantic Ocean and thus provide new constraints for models of atmospheric deposition. The use of the MADCOW model is of major importance as dissolved aluminium is analysed within the GEOTRACES project at high spatial resolution.
Géraldine Sarthou, Pascale Lherminier, Eric P. Achterberg, Fernando Alonso-Pérez, Eva Bucciarelli, Julia Boutorh, Vincent Bouvier, Edward A. Boyle, Pierre Branellec, Lidia I. Carracedo, Nuria Casacuberta, Maxi Castrillejo, Marie Cheize, Leonardo Contreira Pereira, Daniel Cossa, Nathalie Daniault, Emmanuel De Saint-Léger, Frank Dehairs, Feifei Deng, Floriane Desprez de Gésincourt, Jérémy Devesa, Lorna Foliot, Debany Fonseca-Batista, Morgane Gallinari, Maribel I. García-Ibáñez, Arthur Gourain, Emilie Grossteffan, Michel Hamon, Lars Eric Heimbürger, Gideon M. Henderson, Catherine Jeandel, Catherine Kermabon, François Lacan, Philippe Le Bot, Manon Le Goff, Emilie Le Roy, Alison Lefèbvre, Stéphane Leizour, Nolwenn Lemaitre, Pere Masqué, Olivier Ménage, Jan-Lukas Menzel Barraqueta, Herlé Mercier, Fabien Perault, Fiz F. Pérez, Hélène F. Planquette, Frédéric Planchon, Arnout Roukaerts, Virginie Sanial, Raphaëlle Sauzède, Catherine Schmechtig, Rachel U. Shelley, Gillian Stewart, Jill N. Sutton, Yi Tang, Nadine Tisnérat-Laborde, Manon Tonnard, Paul Tréguer, Pieter van Beek, Cheryl M. Zurbrick, and Patricia Zunino
Biogeosciences, 15, 7097–7109, https://doi.org/10.5194/bg-15-7097-2018, https://doi.org/10.5194/bg-15-7097-2018, 2018
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The GEOVIDE cruise (GEOTRACES Section GA01) was conducted in the North Atlantic Ocean and Labrador Sea in May–June 2014. In this special issue, results from GEOVIDE, including physical oceanography and trace element and isotope cyclings, are presented among 17 articles. Here, the scientific context, project objectives, and scientific strategy of GEOVIDE are provided, along with an overview of the main results from the articles published in the special issue.
Jan-Lukas Menzel Barraqueta, Christian Schlosser, Hélène Planquette, Arthur Gourain, Marie Cheize, Julia Boutorh, Rachel Shelley, Leonardo Contreira Pereira, Martha Gledhill, Mark J. Hopwood, François Lacan, Pascale Lherminier, Geraldine Sarthou, and Eric P. Achterberg
Biogeosciences, 15, 5271–5286, https://doi.org/10.5194/bg-15-5271-2018, https://doi.org/10.5194/bg-15-5271-2018, 2018
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In the North Atlantic and Labrador Sea, low aerosol deposition and enhanced primary productivity control the dissolved aluminium (dAl) surface distribution, while remineralization of particles seems to control the distribution at depth. DAl in the ocean allows us to indirectly quantify the amount of dust deposited to a given region for a given period. Hence, the study of its distribution, cycling, sources, and sinks is of major importance to improve aerosol deposition models and climate models.
Christian Schlosser, Katrin Schmidt, Alfred Aquilina, William B. Homoky, Maxi Castrillejo, Rachel A. Mills, Matthew D. Patey, Sophie Fielding, Angus Atkinson, and Eric P. Achterberg
Biogeosciences, 15, 4973–4993, https://doi.org/10.5194/bg-15-4973-2018, https://doi.org/10.5194/bg-15-4973-2018, 2018
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Iron (Fe) emanating from the South Georgia shelf system fuels large phytoplankton blooms downstream of the island. However, the actual supply mechanisms of Fe are unclear. We found that shelf-sediment-derived iron and iron released from Antarctic krill control the Fe distribution in the shelf waters around South Georgia. The majority of the Fe appears to be derived from recycling of Fe-enriched particles that are transported with the water masses into the bloom region.
Yong Zhang, Lennart T. Bach, Kai T. Lohbeck, Kai G. Schulz, Luisa Listmann, Regina Klapper, and Ulf Riebesell
Biogeosciences, 15, 3691–3701, https://doi.org/10.5194/bg-15-3691-2018, https://doi.org/10.5194/bg-15-3691-2018, 2018
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To compare variations in physiological responses to pCO2 between populations, we measured growth, POC and PIC production rates at a pCO2 range from 120 to 2630 µatm for 17 strains of the coccolithophore Emiliania huxleyi from the Azores, Canary Islands, and Norwegian coast near Bergen. Optimal pCO2 for growth and POC production rates and tolerance to low pH was significantly higher for the Bergen population than the Azores and Canary Islands populations.
Natasha A. Gafar and Kai G. Schulz
Biogeosciences, 15, 3541–3560, https://doi.org/10.5194/bg-15-3541-2018, https://doi.org/10.5194/bg-15-3541-2018, 2018
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Emiliania huxleyi and Gephyrocapsa oceanica are the most prolific calcifying phytoplankton in today's oceans. We compare their sensitivity to combined anthropogenic stressors of temperature, light and CO2. For the future, we project a niche contraction for G. oceanica. Furthermore, there was good correlation of our new metric, the CaCO3 production potential, with satellite-derived concentrations in the modern ocean, indicating means of assessing overall coccolithophorid success in the future.
Alyce M. Hancock, Andrew T. Davidson, John McKinlay, Andrew McMinn, Kai G. Schulz, and Rick L. van den Enden
Biogeosciences, 15, 2393–2410, https://doi.org/10.5194/bg-15-2393-2018, https://doi.org/10.5194/bg-15-2393-2018, 2018
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Absorption of carbon dioxide (CO2) realized by humans is decreasing the ocean pH (ocean acidification). Single-celled organisms (microbes) support the Antarctic ecosystem, yet little is known about their sensitivity to ocean acidification. This study shows a shift in a natural Antarctic microbial community, with CO2 levels exceeding 634 μatm changing the community composition and favouring small cells. This would have significant flow effects for Antarctic food webs and elemental cycles.
Stacy Deppeler, Katherina Petrou, Kai G. Schulz, Karen Westwood, Imojen Pearce, John McKinlay, and Andrew Davidson
Biogeosciences, 15, 209–231, https://doi.org/10.5194/bg-15-209-2018, https://doi.org/10.5194/bg-15-209-2018, 2018
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We combined productivity and photophysiology measurements to investigate the effects of ocean acidification on a natural Antarctic marine microbial community. Our study identifies a threshold for CO2 tolerance in the phytoplankton community between 953 and 1140 μatm of CO2, above which productivity declines. Bacteria were tolerant to CO2 up to 1641 μatm. We identify physiological changes in the phytoplankton at high CO2 that allowed them to acclimate to the high CO2 treatment.
Coulson A. Lantz, Kai G. Schulz, Laura Stoltenberg, and Bradley D. Eyre
Biogeosciences, 14, 5377–5391, https://doi.org/10.5194/bg-14-5377-2017, https://doi.org/10.5194/bg-14-5377-2017, 2017
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This study examined the combined effect of seawater warming and organic matter enrichment on coral reef sediment metabolism. Sediments under control conditions were net autotrophic and net calcifying. Warming shifted the sediment to net heterotrophy and net dissolution, while organic matter enrichment increased net production and net calcification. When combined, the effects of each treatment were counterbalanced and sediment metabolism did not significantly differ from control treatments.
Katharine J. Crawfurd, Santiago Alvarez-Fernandez, Kristina D. A. Mojica, Ulf Riebesell, and Corina P. D. Brussaard
Biogeosciences, 14, 3831–3849, https://doi.org/10.5194/bg-14-3831-2017, https://doi.org/10.5194/bg-14-3831-2017, 2017
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Carbon dioxide (CO2) is increasing in the atmosphere and oceans. To simulate future conditions we manipulated CO2 concentrations of natural Baltic seawater in 55 m3 bags in situ. We saw increased growth rates and abundances of the smallest-sized eukaryotic phytoplankton and reduced abundances of other phytoplankton with increased CO2. Viral and bacterial abundances were also affected. This would lead to more carbon recycling in the surface water and affect marine food webs and the carbon cycle.
Giulia Faucher, Linn Hoffmann, Lennart T. Bach, Cinzia Bottini, Elisabetta Erba, and Ulf Riebesell
Biogeosciences, 14, 3603–3613, https://doi.org/10.5194/bg-14-3603-2017, https://doi.org/10.5194/bg-14-3603-2017, 2017
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The main goal of this study was to understand if, similarly to the fossil record, high quantities of toxic metals induce coccolith dwarfism in coccolithophore species. We investigated, for the first time, the effects of trace metals on coccolithophore species other than E. huxleyi and on coccolith morphology and size. Our data show a species-specific sensitivity to trace metal concentration, allowing the recognition of the most-, intermediate- and least-tolerant taxa to trace metal enrichments.
Hanieh T. Farid, Kai G. Schulz, and Andrew L. Rose
Biogeosciences Discuss., https://doi.org/10.5194/bg-2017-129, https://doi.org/10.5194/bg-2017-129, 2017
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This study provides new insights into: (a) how organic exudates from a marine cyanobacterium may influence iron speciation and bioavailability in the extracellular milieu; and (b) approaches for evaluating rate constants for Fe(II) oxidation in the presence of unknown organic ligands. Given that microorganisms play critical roles in biochemical cycling of trace metals in water systems, the findings are expected to improve nutrient uptake models and be of interest to broad range of readers.
Mitchell Call, Kai G. Schulz, Matheus C. Carvalho, Isaac R. Santos, and Damien T. Maher
Biogeosciences, 14, 1305–1313, https://doi.org/10.5194/bg-14-1305-2017, https://doi.org/10.5194/bg-14-1305-2017, 2017
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The conventional method for determining dissolved inorganic carbon (DIC) and it carbon stable isotope ratio (δ13C–DIC) can be a laborious process which can limit sampling frequency. This paper presents a new approach to autonomously determine DIC & δ13C–DIC at high temporal resolution. The simple method requires no customised design. Instead it uses two commercially available instruments and achieved a sampling resolution of 16 mins with precision and accuracy comparable to conventional methods.
Silke Lischka, Lennart T. Bach, Kai-Georg Schulz, and Ulf Riebesell
Biogeosciences, 14, 447–466, https://doi.org/10.5194/bg-14-447-2017, https://doi.org/10.5194/bg-14-447-2017, 2017
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We conducted a large-scale field experiment using 55 m3 floating containers (mesocosms) to investigate consequences of near-future projected CO2 elevations (ocean acidification) on a Baltic Sea plankton community in Storfjärden (Finland). The focus of our study was on single- and multicelled small-sized organisms dwelling in the water column. Our results suggest that increasing CO2 concentrations may change the species composition and promote specific food web interactions.
Enis Hrustić, Risto Lignell, Ulf Riebesell, and Tron Frede Thingstad
Biogeosciences, 14, 379–387, https://doi.org/10.5194/bg-14-379-2017, https://doi.org/10.5194/bg-14-379-2017, 2017
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Phytoplankton in the ocean's stratified layer are limited by mineral nutrients, normally nitrogen, phosphorus, or iron. It is important to know not only which element is limiting, but also the surplus of the secondary limiting element. We explore here, in temperate mesotrophic waters, a bioassay based on alkaline phosphatase that provides information on both of these.
Thomas Hornick, Lennart T. Bach, Katharine J. Crawfurd, Kristian Spilling, Eric P. Achterberg, Jason N. Woodhouse, Kai G. Schulz, Corina P. D. Brussaard, Ulf Riebesell, and Hans-Peter Grossart
Biogeosciences, 14, 1–15, https://doi.org/10.5194/bg-14-1-2017, https://doi.org/10.5194/bg-14-1-2017, 2017
Rafael Bermúdez, Monika Winder, Annegret Stuhr, Anna-Karin Almén, Jonna Engström-Öst, and Ulf Riebesell
Biogeosciences, 13, 6625–6635, https://doi.org/10.5194/bg-13-6625-2016, https://doi.org/10.5194/bg-13-6625-2016, 2016
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Increasing CO2 is changing seawater chemistry towards a lower pH, which affects marine organisms. We investigate the response of a brackish plankton community to a CO2 gradient in terms of structure and fatty acid composition. The structure was resilient to CO2 and did not diverge between treatments. FA was influenced by community structure, which was driven by silicate and phosphate. This suggests that CO2 effects are dampened in communities already experiencing high natural pCO2 fluctuation.
Anu Vehmaa, Anna-Karin Almén, Andreas Brutemark, Allanah Paul, Ulf Riebesell, Sara Furuhagen, and Jonna Engström-Öst
Biogeosciences, 13, 6171–6182, https://doi.org/10.5194/bg-13-6171-2016, https://doi.org/10.5194/bg-13-6171-2016, 2016
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Ocean acidification is challenging phenotypic plasticity of individuals and populations. We studied phenotypic plasticity of the calanoid copepod Acartia bifilosa in the course of a pelagic, large-volume mesocosm study in the Baltic Sea. We found significant negative effects of ocean acidification on adult female copepod size and egg hatching success. Overall, these results indicate that A. bifilosa could be affected by projected near-future CO2 levels.
Kristian Spilling, Kai G. Schulz, Allanah J. Paul, Tim Boxhammer, Eric P. Achterberg, Thomas Hornick, Silke Lischka, Annegret Stuhr, Rafael Bermúdez, Jan Czerny, Kate Crawfurd, Corina P. D. Brussaard, Hans-Peter Grossart, and Ulf Riebesell
Biogeosciences, 13, 6081–6093, https://doi.org/10.5194/bg-13-6081-2016, https://doi.org/10.5194/bg-13-6081-2016, 2016
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We performed an experiment in the Baltic Sea in order to investigate the consequences of the increasing CO2 levels on biological processes in the free water mass. There was more accumulation of organic carbon at high CO2 levels. Surprisingly, this was caused by reduced loss processes (respiration and bacterial production) in a high-CO2 environment, and not by increased photosynthetic fixation of CO2. Our carbon budget can be used to better disentangle the effects of ocean acidification.
Francesca Gallo, Kai G. Schulz, Eduardo B. Azevedo, João Madruga, and Joana Barcelos e Ramos
Biogeosciences Discuss., https://doi.org/10.5194/bg-2016-352, https://doi.org/10.5194/bg-2016-352, 2016
Revised manuscript not accepted
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Global change driven by humans activities may affect phytoplankton, which are important primary producers. Assessing the combined effect of turbulence and ocean acidification on the species Asterionellopsis glacialis, we found that turbulence magnifies the acidification stress, with negative effects on their growth. In the natural environment, this might have consequences to phytoplankton community composition and production with feedbacks to climate.
Kristian Spilling, Allanah J. Paul, Niklas Virkkala, Tom Hastings, Silke Lischka, Annegret Stuhr, Rafael Bermúdez, Jan Czerny, Tim Boxhammer, Kai G. Schulz, Andrea Ludwig, and Ulf Riebesell
Biogeosciences, 13, 4707–4719, https://doi.org/10.5194/bg-13-4707-2016, https://doi.org/10.5194/bg-13-4707-2016, 2016
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Anthropogenic carbon dioxide (CO2) emissions are reducing the pH in the world's oceans. We determined the plankton community composition and measured primary production, respiration rates and carbon export during an ocean acidification experiment. Our results suggest that increased CO2 reduced respiration and increased net carbon fixation at high CO2. This did not, however, translate into higher carbon export, and consequently did not work as a negative feedback mechanism for decreasing pH.
Juntian Xu, Lennart T. Bach, Kai G. Schulz, Wenyan Zhao, Kunshan Gao, and Ulf Riebesell
Biogeosciences, 13, 4637–4643, https://doi.org/10.5194/bg-13-4637-2016, https://doi.org/10.5194/bg-13-4637-2016, 2016
Alison L. Webb, Emma Leedham-Elvidge, Claire Hughes, Frances E. Hopkins, Gill Malin, Lennart T. Bach, Kai Schulz, Kate Crawfurd, Corina P. D. Brussaard, Annegret Stuhr, Ulf Riebesell, and Peter S. Liss
Biogeosciences, 13, 4595–4613, https://doi.org/10.5194/bg-13-4595-2016, https://doi.org/10.5194/bg-13-4595-2016, 2016
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This paper presents concentrations of several trace gases produced by the Baltic Sea phytoplankton community during a mesocosm experiment with five different CO2 levels. Average concentrations of dimethylsulphide were lower in the highest CO2 mesocosms over a 6-week period, corresponding to previous mesocosm experiment results. No dimethylsulfoniopropionate was detected due to a methodological issue. Concentrations of iodine- and bromine-containing halocarbons were unaffected by increasing CO2.
Carolin R. Löscher, Hermann W. Bange, Ruth A. Schmitz, Cameron M. Callbeck, Anja Engel, Helena Hauss, Torsten Kanzow, Rainer Kiko, Gaute Lavik, Alexandra Loginova, Frank Melzner, Judith Meyer, Sven C. Neulinger, Markus Pahlow, Ulf Riebesell, Harald Schunck, Sören Thomsen, and Hannes Wagner
Biogeosciences, 13, 3585–3606, https://doi.org/10.5194/bg-13-3585-2016, https://doi.org/10.5194/bg-13-3585-2016, 2016
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The ocean loses oxygen due to climate change. Addressing this issue in tropical ocean regions (off Peru and Mauritania), we aimed to understand the effects of oxygen depletion on various aspects of marine biogeochemistry, including primary production and export production, the nitrogen cycle, greenhouse gas production, organic matter fluxes and remineralization, and the role of zooplankton and viruses.
Anna Jansson, Silke Lischka, Tim Boxhammer, Kai G. Schulz, and Joanna Norkko
Biogeosciences, 13, 3377–3385, https://doi.org/10.5194/bg-13-3377-2016, https://doi.org/10.5194/bg-13-3377-2016, 2016
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We studied the responses of larvae of Macoma balthica to a range of future CO2 scenarios using large mesocosms encompassing the entire pelagic community. We focused on the growth and settlement process of M. balthica when exposed to future CO2 levels, and found the size and time to settlement to increase along the CO2 gradient, suggesting a developmental delay. The strong impact of increasing CO2 on early-stage bivalves is alarming as these stages are crucial for sustaining viable populations.
Matthew P. Humphreys, Florence M. Greatrix, Eithne Tynan, Eric P. Achterberg, Alex M. Griffiths, Claudia H. Fry, Rebecca Garley, Alison McDonald, and Adrian J. Boyce
Earth Syst. Sci. Data, 8, 221–233, https://doi.org/10.5194/essd-8-221-2016, https://doi.org/10.5194/essd-8-221-2016, 2016
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This paper reports the stable isotope composition of dissolved inorganic carbon in seawater for a transect from west to east across the North Atlantic Ocean. The results can be used to study oceanic uptake of anthropogenic carbon dioxide, and also to investigate the natural biological carbon pump. We also provide stable DIC isotope results for two batches of Dickson seawater CRMs to enable intercomparisons with other studies.
Monika Nausch, Lennart Thomas Bach, Jan Czerny, Josephine Goldstein, Hans-Peter Grossart, Dana Hellemann, Thomas Hornick, Eric Pieter Achterberg, Kai-Georg Schulz, and Ulf Riebesell
Biogeosciences, 13, 3035–3050, https://doi.org/10.5194/bg-13-3035-2016, https://doi.org/10.5194/bg-13-3035-2016, 2016
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Studies investigating the effect of increasing CO2 levels on the phosphorus cycle in natural waters are lacking although phosphorus often controls phytoplankton development in aquatic systems. The aim of our study was to analyse effects of elevated CO2 levels on phosphorus pool sizes and uptake. Therefore, we conducted a CO2-manipulation mesocosm experiment in the Storfjärden (western Gulf of Finland, Baltic Sea) in summer 2012. We compared the phosphorus dynamics in different mesocosm treatment
Tim Boxhammer, Lennart T. Bach, Jan Czerny, and Ulf Riebesell
Biogeosciences, 13, 2849–2858, https://doi.org/10.5194/bg-13-2849-2016, https://doi.org/10.5194/bg-13-2849-2016, 2016
Anna-Karin Almén, Anu Vehmaa, Andreas Brutemark, Lennart Bach, Silke Lischka, Annegret Stuhr, Sara Furuhagen, Allanah Paul, J. Rafael Bermúdez, Ulf Riebesell, and Jonna Engström-Öst
Biogeosciences, 13, 1037–1048, https://doi.org/10.5194/bg-13-1037-2016, https://doi.org/10.5194/bg-13-1037-2016, 2016
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We studied the effects of ocean acidification (OA) on the aquatic crustacean Eurytemora affinis and measured offspring production in relation to pH, chlorophyll, algae, fatty acids, and oxidative stress. No effects on offspring production or pH effects via food were found. E. affinis seems robust against OA on a physiological level and did probably not face acute pH stress in the treatments, as the species naturally face large pH fluctuations.
J. Meyer, C. R. Löscher, S. C. Neulinger, A. F. Reichel, A. Loginova, C. Borchard, R. A. Schmitz, H. Hauss, R. Kiko, and U. Riebesell
Biogeosciences, 13, 781–794, https://doi.org/10.5194/bg-13-781-2016, https://doi.org/10.5194/bg-13-781-2016, 2016
M. N. Müller, J. Barcelos e Ramos, K. G. Schulz, U. Riebesell, J. Kaźmierczak, F. Gallo, L. Mackinder, Y. Li, P. N. Nesterenko, T. W. Trull, and G. M. Hallegraeff
Biogeosciences, 12, 6493–6501, https://doi.org/10.5194/bg-12-6493-2015, https://doi.org/10.5194/bg-12-6493-2015, 2015
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The White Cliffs of Dover date back to the Cretaceous and are made up of microscopic chalky shells which were produced mainly by marine phytoplankton (coccolithophores). This is iconic proof for their success at times of relatively high seawater calcium concentrations and, as shown here, to be linked to their ability to precipitate calcium as chalk. The invention of calcification can thus be considered an evolutionary milestone allowing coccolithophores to thrive at times when others struggled.
A. Singh, S. E. Baer, U. Riebesell, A. C. Martiny, and M. W. Lomas
Biogeosciences, 12, 6389–6403, https://doi.org/10.5194/bg-12-6389-2015, https://doi.org/10.5194/bg-12-6389-2015, 2015
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Stoichiometry of macronutrients in the subtropical ocean is important to understand how biogeochemical cycles are coupled. We observed that elemental stoichiometry was much higher in the dissolved organic-matter pools than in the particulate organic matter pools. In addition ratios vary with depth due to changes in growth rates of specific phytoplankton groups, namely cyanobacteria. These data will improve biogeochemical models by placing observational constraints on these ratios.
A. J. Paul, L. T. Bach, K.-G. Schulz, T. Boxhammer, J. Czerny, E. P. Achterberg, D. Hellemann, Y. Trense, M. Nausch, M. Sswat, and U. Riebesell
Biogeosciences, 12, 6181–6203, https://doi.org/10.5194/bg-12-6181-2015, https://doi.org/10.5194/bg-12-6181-2015, 2015
Y. Zhang, N. Mahowald, R. A. Scanza, E. Journet, K. Desboeufs, S. Albani, J. F. Kok, G. Zhuang, Y. Chen, D. D. Cohen, A. Paytan, M. D. Patey, E. P. Achterberg, J. P. Engelbrecht, and K. W. Fomba
Biogeosciences, 12, 5771–5792, https://doi.org/10.5194/bg-12-5771-2015, https://doi.org/10.5194/bg-12-5771-2015, 2015
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A new technique to determine a size-fractionated global soil elemental emission inventory based on a global soil and mineralogical data set is introduced. Spatial variability of mineral dust elemental fractions (8 elements, e.g., Ca, Fe, Al) is identified on a global scale, particularly for Ca. The Ca/Al ratio ranged between 0.1 and 5.0 and is confirmed as an indicator of dust source regions by a global dust model. Total and soluble dust element fluxes into different ocean basins are estimated.
T. Larsen, L. T. Bach, R. Salvatteci, Y. V. Wang, N. Andersen, M. Ventura, and M. D. McCarthy
Biogeosciences, 12, 4979–4992, https://doi.org/10.5194/bg-12-4979-2015, https://doi.org/10.5194/bg-12-4979-2015, 2015
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A tiny fraction of marine algae escapes decomposition and is buried in sediments. Since tools are needed to track the fate of algal organic carbon, we tested whether naturally occurring isotope variability among amino acids from algae and bacteria can be used as source diagnostic fingerprints. We found that isotope fingerprints track algal amino acid sources with high fidelity across different growth conditions, and that the fingerprints can be used to quantify bacterial amino acids in sediment.
L. T. Bach
Biogeosciences, 12, 4939–4951, https://doi.org/10.5194/bg-12-4939-2015, https://doi.org/10.5194/bg-12-4939-2015, 2015
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Calcification by marine organisms reacts to changing seawater carbonate chemistry, but it is unclear which components of the carbonate system drive the observed response. This study uncovers proportionalities between different carbonate chemistry parameters. These enable us to understand why calcification often correlates well with carbonate ion concentration, and they imply that net CaCO3 formation in high latitudes is not more vulnerable to ocean acidification than formation in low latitudes.
M. P. Humphreys, E. P. Achterberg, A. M. Griffiths, A. McDonald, and A. J. Boyce
Earth Syst. Sci. Data, 7, 127–135, https://doi.org/10.5194/essd-7-127-2015, https://doi.org/10.5194/essd-7-127-2015, 2015
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We present measurements of the stable carbon isotope composition of seawater dissolved inorganic carbon. The samples were collected during two research cruises in boreal summer 2012 in the northeastern Atlantic and Nordic Seas. The results can be used to investigate the marine carbon cycle, providing information about biological productivity and oceanic uptake of anthropogenic carbon dioxide.
J. Meyer and U. Riebesell
Biogeosciences, 12, 1671–1682, https://doi.org/10.5194/bg-12-1671-2015, https://doi.org/10.5194/bg-12-1671-2015, 2015
S. A. Krueger-Hadfield, C. Balestreri, J. Schroeder, A. Highfield, P. Helaouët, J. Allum, R. Moate, K. T. Lohbeck, P. I. Miller, U. Riebesell, T. B. H. Reusch, R. E. M. Rickaby, J. Young, G. Hallegraeff, C. Brownlee, and D. C. Schroeder
Biogeosciences, 11, 5215–5234, https://doi.org/10.5194/bg-11-5215-2014, https://doi.org/10.5194/bg-11-5215-2014, 2014
M. N. Müller, M. Lebrato, U. Riebesell, J. Barcelos e Ramos, K. G. Schulz, S. Blanco-Ameijeiras, S. Sett, A. Eisenhauer, and H. M. Stoll
Biogeosciences, 11, 1065–1075, https://doi.org/10.5194/bg-11-1065-2014, https://doi.org/10.5194/bg-11-1065-2014, 2014
A. Silyakova, R. G. J. Bellerby, K. G. Schulz, J. Czerny, T. Tanaka, G. Nondal, U. Riebesell, A. Engel, T. De Lange, and A. Ludvig
Biogeosciences, 10, 4847–4859, https://doi.org/10.5194/bg-10-4847-2013, https://doi.org/10.5194/bg-10-4847-2013, 2013
J. Czerny, K. G. Schulz, T. Boxhammer, R. G. J. Bellerby, J. Büdenbender, A. Engel, S. A. Krug, A. Ludwig, K. Nachtigall, G. Nondal, B. Niehoff, A. Silyakova, and U. Riebesell
Biogeosciences, 10, 3109–3125, https://doi.org/10.5194/bg-10-3109-2013, https://doi.org/10.5194/bg-10-3109-2013, 2013
J. Czerny, K. G. Schulz, S. A. Krug, A. Ludwig, and U. Riebesell
Biogeosciences, 10, 1937–1941, https://doi.org/10.5194/bg-10-1937-2013, https://doi.org/10.5194/bg-10-1937-2013, 2013
U. Riebesell, J. Czerny, K. von Bröckel, T. Boxhammer, J. Büdenbender, M. Deckelnick, M. Fischer, D. Hoffmann, S. A. Krug, U. Lentz, A. Ludwig, R. Muche, and K. G. Schulz
Biogeosciences, 10, 1835–1847, https://doi.org/10.5194/bg-10-1835-2013, https://doi.org/10.5194/bg-10-1835-2013, 2013
N. Aberle, K. G. Schulz, A. Stuhr, A. M. Malzahn, A. Ludwig, and U. Riebesell
Biogeosciences, 10, 1471–1481, https://doi.org/10.5194/bg-10-1471-2013, https://doi.org/10.5194/bg-10-1471-2013, 2013
A. de Kluijver, K. Soetaert, J. Czerny, K. G. Schulz, T. Boxhammer, U. Riebesell, and J. J. Middelburg
Biogeosciences, 10, 1425–1440, https://doi.org/10.5194/bg-10-1425-2013, https://doi.org/10.5194/bg-10-1425-2013, 2013
A. Engel, C. Borchard, J. Piontek, K. G. Schulz, U. Riebesell, and R. Bellerby
Biogeosciences, 10, 1291–1308, https://doi.org/10.5194/bg-10-1291-2013, https://doi.org/10.5194/bg-10-1291-2013, 2013
B. Niehoff, T. Schmithüsen, N. Knüppel, M. Daase, J. Czerny, and T. Boxhammer
Biogeosciences, 10, 1391–1406, https://doi.org/10.5194/bg-10-1391-2013, https://doi.org/10.5194/bg-10-1391-2013, 2013
E. Leu, M. Daase, K. G. Schulz, A. Stuhr, and U. Riebesell
Biogeosciences, 10, 1143–1153, https://doi.org/10.5194/bg-10-1143-2013, https://doi.org/10.5194/bg-10-1143-2013, 2013
C. P. D. Brussaard, A. A. M. Noordeloos, H. Witte, M. C. J. Collenteur, K. Schulz, A. Ludwig, and U. Riebesell
Biogeosciences, 10, 719–731, https://doi.org/10.5194/bg-10-719-2013, https://doi.org/10.5194/bg-10-719-2013, 2013
A.-S. Roy, S. M. Gibbons, H. Schunck, S. Owens, J. G. Caporaso, M. Sperling, J. I. Nissimov, S. Romac, L. Bittner, M. Mühling, U. Riebesell, J. LaRoche, and J. A. Gilbert
Biogeosciences, 10, 555–566, https://doi.org/10.5194/bg-10-555-2013, https://doi.org/10.5194/bg-10-555-2013, 2013
T. Tanaka, S. Alliouane, R. G. B. Bellerby, J. Czerny, A. de Kluijver, U. Riebesell, K. G. Schulz, A. Silyakova, and J.-P. Gattuso
Biogeosciences, 10, 315–325, https://doi.org/10.5194/bg-10-315-2013, https://doi.org/10.5194/bg-10-315-2013, 2013
J. Piontek, C. Borchard, M. Sperling, K. G. Schulz, U. Riebesell, and A. Engel
Biogeosciences, 10, 297–314, https://doi.org/10.5194/bg-10-297-2013, https://doi.org/10.5194/bg-10-297-2013, 2013
M. Sperling, J. Piontek, G. Gerdts, A. Wichels, H. Schunck, A.-S. Roy, J. La Roche, J. Gilbert, J. I. Nissimov, L. Bittner, S. Romac, U. Riebesell, and A. Engel
Biogeosciences, 10, 181–191, https://doi.org/10.5194/bg-10-181-2013, https://doi.org/10.5194/bg-10-181-2013, 2013
K. G. Schulz, R. G. J. Bellerby, C. P. D. Brussaard, J. Büdenbender, J. Czerny, A. Engel, M. Fischer, S. Koch-Klavsen, S. A. Krug, S. Lischka, A. Ludwig, M. Meyerhöfer, G. Nondal, A. Silyakova, A. Stuhr, and U. Riebesell
Biogeosciences, 10, 161–180, https://doi.org/10.5194/bg-10-161-2013, https://doi.org/10.5194/bg-10-161-2013, 2013
Related subject area
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Effect of terrestrial nutrient limitation on the estimation of the remaining carbon budget
Projected changes in forest fire season, the number of fires, and burnt area in Fennoscandia by 2100
New ozone–nitrogen model shows early senescence onset is the primary cause of ozone-induced reduction in grain quality of wheat
Ocean alkalinity enhancement approaches and the predictability of runaway precipitation processes: results of an experimental study to determine critical alkalinity ranges for safe and sustainable application scenarios
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The Southern Ocean as the climate's freight train – driving ongoing global warming under zero-emission scenarios with ACCESS-ESM1.5
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Southern Ocean phytoplankton under climate change: a shifting balance of bottom-up and top-down control
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Direct foliar phosphorus uptake from wildfire ash
Unifying framework for assessing sensitivity for marine calcifiers to ocean alkalinity enhancement identifies winners, losers and biological thresholds – importance of caution with precautionary principle
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Reconciling different approaches to quantifying land surface temperature impacts of afforestation using satellite observations
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Makcim L. De Sisto and Andrew H. MacDougall
Biogeosciences, 21, 4853–4873, https://doi.org/10.5194/bg-21-4853-2024, https://doi.org/10.5194/bg-21-4853-2024, 2024
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The remaining carbon budget (RCB) represents the allowable future CO2 emissions before a temperature target is reached. Understanding the uncertainty in the RCB is critical for effective climate regulation and policy-making. One major source of uncertainty is the representation of the carbon cycle in Earth system models. We assessed how nutrient limitation affects the estimation of the RCB. We found a reduction in the estimated RCB when nutrient limitation is taken into account.
Outi Kinnunen, Leif Backman, Juha Aalto, Tuula Aalto, and Tiina Markkanen
Biogeosciences, 21, 4739–4763, https://doi.org/10.5194/bg-21-4739-2024, https://doi.org/10.5194/bg-21-4739-2024, 2024
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Climate change is expected to increase the risk of forest fires. Ecosystem process model simulations are used to project changes in fire occurrence in Fennoscandia under six climate projections. The findings suggest a longer fire season, more fires, and an increase in burnt area towards the end of the century.
Jo Cook, Clare Brewster, Felicity Hayes, Nathan Booth, Sam Bland, Pritha Pande, Samarthia Thankappan, Håkan Pleijel, and Lisa Emberson
Biogeosciences, 21, 4809–4835, https://doi.org/10.5194/bg-21-4809-2024, https://doi.org/10.5194/bg-21-4809-2024, 2024
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At ground level, the air pollutant ozone (O3) damages wheat yield and quality. We modified the DO3SE-Crop model to simulate O3 effects on wheat quality and identified onset of leaf death as the key process affecting wheat quality upon O3 exposure. This aligns with expectations, as the onset of leaf death aids nutrient transfer from leaves to grains. Breeders should prioritize wheat varieties resistant to protein loss from delayed leaf death, to maintain yield and quality under O3 exposure.
Niels Suitner, Giulia Faucher, Carl Lim, Julieta Schneider, Charly A. Moras, Ulf Riebesell, and Jens Hartmann
Biogeosciences, 21, 4587–4604, https://doi.org/10.5194/bg-21-4587-2024, https://doi.org/10.5194/bg-21-4587-2024, 2024
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Recent studies described the precipitation of carbonates as a result of alkalinity enhancement in seawater, which could adversely affect the carbon sequestration potential of ocean alkalinity enhancement (OAE) approaches. By conducting experiments in natural seawater, this study observed uniform patterns during the triggered runaway carbonate precipitation, which allow the prediction of safe and efficient local application levels of OAE scenarios.
Milagros Rico, Paula Santiago-Díaz, Guillermo Samperio-Ramos, Melchor González-Dávila, and Juana Magdalena Santana-Casiano
Biogeosciences, 21, 4381–4394, https://doi.org/10.5194/bg-21-4381-2024, https://doi.org/10.5194/bg-21-4381-2024, 2024
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Changes in pH generate stress conditions, either because high pH drastically decreases the availability of trace metals such as Fe(II), a restrictive element for primary productivity, or because reactive oxygen species are increased with low pH. The metabolic functions and composition of microalgae can be affected. These modifications in metabolites are potential factors leading to readjustments in phytoplankton community structure and diversity and possible alteration in marine ecosystems.
James A. King, James Weber, Peter Lawrence, Stephanie Roe, Abigail L. S. Swann, and Maria Val Martin
Biogeosciences, 21, 3883–3902, https://doi.org/10.5194/bg-21-3883-2024, https://doi.org/10.5194/bg-21-3883-2024, 2024
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Tackling climate change by adding, restoring, or enhancing forests is gaining global support. However, it is important to investigate the broader implications of this. We used a computer model of the Earth to investigate a future where tree cover expanded as much as possible. We found that some tropical areas were cooler because of trees pumping water into the atmosphere, but this also led to soil and rivers drying. This is important because it might be harder to maintain forests as a result.
Benoît Pasquier, Mark Holzer, and Matthew A. Chamberlain
Biogeosciences, 21, 3373–3400, https://doi.org/10.5194/bg-21-3373-2024, https://doi.org/10.5194/bg-21-3373-2024, 2024
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How do perpetually slower and warmer oceans sequester carbon? Compared to the preindustrial state, we find that biological productivity declines despite warming-stimulated growth because of a lower nutrient supply from depth. This throttles the biological carbon pump, which still sequesters more carbon because it takes longer to return to the surface. The deep ocean is isolated from the surface, allowing more carbon from the atmosphere to pass through the ocean without contributing to biology.
Matthew A. Chamberlain, Tilo Ziehn, and Rachel M. Law
Biogeosciences, 21, 3053–3073, https://doi.org/10.5194/bg-21-3053-2024, https://doi.org/10.5194/bg-21-3053-2024, 2024
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This paper explores the climate processes that drive increasing global average temperatures in zero-emission commitment (ZEC) simulations despite decreasing atmospheric CO2. ACCESS-ESM1.5 shows the Southern Ocean to continue to warm locally in all ZEC simulations. In ZEC simulations that start after the emission of more than 1000 Pg of carbon, the influence of the Southern Ocean increases the global temperature.
Shuaifeng Song, Xuezhen Zhang, and Xiaodong Yan
Biogeosciences, 21, 2839–2858, https://doi.org/10.5194/bg-21-2839-2024, https://doi.org/10.5194/bg-21-2839-2024, 2024
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We mapped the distribution of future potential afforestation regions based on future high-resolution climate data and climate–vegetation models. After considering the national afforestation policy and climate change, we found that the future potential afforestation region was mainly located around and to the east of the Hu Line. This study provides a dataset for exploring the effects of future afforestation.
Tianfei Xue, Jens Terhaar, A. E. Friederike Prowe, Thomas L. Frölicher, Andreas Oschlies, and Ivy Frenger
Biogeosciences, 21, 2473–2491, https://doi.org/10.5194/bg-21-2473-2024, https://doi.org/10.5194/bg-21-2473-2024, 2024
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Phytoplankton play a crucial role in marine ecosystems. However, climate change's impact on phytoplankton biomass remains uncertain, particularly in the Southern Ocean. In this region, phytoplankton biomass within the water column is likely to remain stable in response to climate change, as supported by models. This stability arises from a shallower mixed layer, favoring phytoplankton growth but also increasing zooplankton grazing due to phytoplankton concentration near the surface.
Kinga Kulesza and Agata Hościło
Biogeosciences, 21, 2509–2527, https://doi.org/10.5194/bg-21-2509-2024, https://doi.org/10.5194/bg-21-2509-2024, 2024
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We present coherence and time lags in spectral response of three vegetation types in the European temperate zone to the influencing meteorological factors and teleconnection indices for the period 2002–2022. Vegetation condition in broadleaved forest, coniferous forest and pastures was measured with MODIS NDVI and EVI, and the coherence between NDVI and EVI and meteorological elements was described using the methods of wavelet coherence and Pearson’s linear correlation with time lag.
Anton Lokshin, Daniel Palchan, and Avner Gross
Biogeosciences, 21, 2355–2365, https://doi.org/10.5194/bg-21-2355-2024, https://doi.org/10.5194/bg-21-2355-2024, 2024
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Ash particles from wildfires are rich in phosphorus (P), a crucial nutrient that constitutes a limiting factor in 43 % of the world's land ecosystems. We hypothesize that wildfire ash could directly contribute to plant nutrition. We find that fire ash application boosts the growth of plants, but the only way plants can uptake P from fire ash is through the foliar uptake pathway and not through the roots. The fertilization impact of fire ash was also maintained under elevated levels of CO2.
Nina Bednaršek, Greg Pelletier, Hanna van de Mortel, Marisol García-Reyes, Richard Feely, and Andrew Dickson
EGUsphere, https://doi.org/10.5194/egusphere-2024-947, https://doi.org/10.5194/egusphere-2024-947, 2024
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The environmental impacts of ocean alkalinity enhancement (OAE) are unknown. A conceptual framework was developed showing 40 % of species to respond positively, 20 % negatively and 40 % with neutral response upon alkalinity addition. Biological thresholds were found between 10 to 500 µmol/kg NaOH addition, emphasizing lab experiments to be conducted at lower dosages. A precautionary approach is warranted to avoid potential risks.
Mana Gharun, Ankit Shekhar, Jingfeng Xiao, Xing Li, and Nina Buchmann
EGUsphere, https://doi.org/10.5194/egusphere-2024-423, https://doi.org/10.5194/egusphere-2024-423, 2024
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In 2022, Europe's forests faced unprecedented dry conditions. Our study aimed to understand how different forest types respond to extreme drought. Using meteorological data and satellite imagery, we compared 2022 with two previous extreme years, 2003 and 2018. Despite less severe drought in 2022, forests showed a 30 % greater decline in photosynthesis compared to 2018 and 60 % more than 2003. This suggests a concerning trend of declining forest resilience to more frequent droughts.
Marcus Breil, Vanessa K. M. Schneider, and Joaquim G. Pinto
Biogeosciences, 21, 811–824, https://doi.org/10.5194/bg-21-811-2024, https://doi.org/10.5194/bg-21-811-2024, 2024
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The general impact of afforestation on the regional climate conditions in Europe during the period 1986–2015 is investigated. For this purpose, a regional climate model simulation is performed, in which afforestation during this period is considered, and results are compared to a simulation in which this is not the case. Results show that afforestation had discernible impacts on the climate change signal in Europe, which may have mitigated the local warming trend, especially in summer in Europe.
Ali Asaadi, Jörg Schwinger, Hanna Lee, Jerry Tjiputra, Vivek Arora, Roland Séférian, Spencer Liddicoat, Tomohiro Hajima, Yeray Santana-Falcón, and Chris D. Jones
Biogeosciences, 21, 411–435, https://doi.org/10.5194/bg-21-411-2024, https://doi.org/10.5194/bg-21-411-2024, 2024
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Carbon cycle feedback metrics are employed to assess phases of positive and negative CO2 emissions. When emissions become negative, we find that the model disagreement in feedback metrics increases more strongly than expected from the assumption that the uncertainties accumulate linearly with time. The geographical patterns of such metrics over land highlight that differences in response between tropical/subtropical and temperate/boreal ecosystems are a major source of model disagreement.
Thuy Huu Nguyen, Thomas Gaiser, Jan Vanderborght, Andrea Schnepf, Felix Bauer, Anja Klotzsche, Lena Lärm, Hubert Hüging, and Frank Ewert
EGUsphere, https://doi.org/10.5194/egusphere-2023-2967, https://doi.org/10.5194/egusphere-2023-2967, 2024
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Leaf water potential was at certain thresholds which depends on soil types, water treatment, and weather conditions. In rainfed plot, the lower water availability in the stony soil resulted in less roots with a higher root tissue conductance than the silty soil. In silty soil, higher stress in the rainfed soil led to more roots with a lower root tissue conductance than in the irrigated plot. Crop responses to water stress can be opposite depending on soil water conditions that are compared.
Flora Desmet, Matthias Münnich, and Nicolas Gruber
Biogeosciences, 20, 5151–5175, https://doi.org/10.5194/bg-20-5151-2023, https://doi.org/10.5194/bg-20-5151-2023, 2023
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Ocean acidity extremes in the upper 250 m depth of the northeastern Pacific rapidly increase with atmospheric CO2 rise, which is worrisome for marine organisms that rapidly experience pH levels outside their local environmental conditions. Presented research shows the spatiotemporal heterogeneity in this increase between regions and depths. In particular, the subsurface increase is substantially slowed down by the presence of mesoscale eddies, often not resolved in Earth system models.
Philipp Suessle, Jan Taucher, Silvan Goldenberg, Moritz Baumann, Kristian Spilling, Andrea Noche-Ferreira, Mari Vanharanta, and Ulf Riebesell
EGUsphere, https://doi.org/10.5194/egusphere-2023-2800, https://doi.org/10.5194/egusphere-2023-2800, 2023
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Ocean alkalinity enhancement (OAE) is a negative emission technology which may alter marine communities and the particle export they drive. Here, impacts of carbonate-based OAE on the flux and attenuation of sinking particles in an oligotrophic plankton community are presented. Whilst biological parameters remained unaffected, abiotic carbonate precipitation occurred. Among counteracting OAE’s efficiency, it influenced mineral ballasting and particle sinking velocities, requiring monitoring.
Geneviève W. Elsworth, Nicole S. Lovenduski, Kristen M. Krumhardt, Thomas M. Marchitto, and Sarah Schlunegger
Biogeosciences, 20, 4477–4490, https://doi.org/10.5194/bg-20-4477-2023, https://doi.org/10.5194/bg-20-4477-2023, 2023
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Anthropogenic climate change will influence marine phytoplankton over the coming century. Here, we quantify the influence of anthropogenic climate change on marine phytoplankton internal variability using an Earth system model ensemble and identify a decline in global phytoplankton biomass variance with warming. Our results suggest that climate mitigation efforts that account for marine phytoplankton changes should also consider changes in phytoplankton variance driven by anthropogenic warming.
Olivia Haas, Iain Colin Prentice, and Sandy P. Harrison
Biogeosciences, 20, 3981–3995, https://doi.org/10.5194/bg-20-3981-2023, https://doi.org/10.5194/bg-20-3981-2023, 2023
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We quantify the impact of CO2 and climate on global patterns of burnt area, fire size, and intensity under Last Glacial Maximum (LGM) conditions using three climate scenarios. Climate change alone did not produce the observed LGM reduction in burnt area, but low CO2 did through reducing vegetation productivity. Fire intensity was sensitive to CO2 but strongly affected by changes in atmospheric dryness. Low CO2 caused smaller fires; climate had the opposite effect except in the driest scenario.
Rebecca M. Varney, Sarah E. Chadburn, Eleanor J. Burke, Simon Jones, Andy J. Wiltshire, and Peter M. Cox
Biogeosciences, 20, 3767–3790, https://doi.org/10.5194/bg-20-3767-2023, https://doi.org/10.5194/bg-20-3767-2023, 2023
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This study evaluates soil carbon projections during the 21st century in CMIP6 Earth system models. In general, we find a reduced spread of changes in global soil carbon in CMIP6 compared to the previous CMIP5 generation. The reduced CMIP6 spread arises from an emergent relationship between soil carbon changes due to change in plant productivity and soil carbon changes due to changes in turnover time. We show that this relationship is consistent with false priming under transient climate change.
Claudia Hinrichs, Peter Köhler, Christoph Völker, and Judith Hauck
Biogeosciences, 20, 3717–3735, https://doi.org/10.5194/bg-20-3717-2023, https://doi.org/10.5194/bg-20-3717-2023, 2023
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This study evaluated the alkalinity distribution in 14 climate models and found that most models underestimate alkalinity at the surface and overestimate it in the deeper ocean. It highlights the need for better understanding and quantification of processes driving alkalinity distribution and calcium carbonate dissolution and the importance of accounting for biases in model results when evaluating potential ocean alkalinity enhancement experiments.
Yonghong Zheng, Huanfeng Shen, Rory Abernethy, and Rob Wilson
Biogeosciences, 20, 3481–3490, https://doi.org/10.5194/bg-20-3481-2023, https://doi.org/10.5194/bg-20-3481-2023, 2023
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Investigations in central and western China show that tree ring inverted latewood intensity expresses a strong positive relationship with growing-season temperatures, indicating exciting potential for regions south of 30° N that are traditionally not targeted for temperature reconstructions. Earlywood BI also shows good potential to reconstruct hydroclimate parameters in some humid areas and will enhance ring-width-based hydroclimate reconstructions in the future.
Stefano Potter, Sol Cooperdock, Sander Veraverbeke, Xanthe Walker, Michelle C. Mack, Scott J. Goetz, Jennifer Baltzer, Laura Bourgeau-Chavez, Arden Burrell, Catherine Dieleman, Nancy French, Stijn Hantson, Elizabeth E. Hoy, Liza Jenkins, Jill F. Johnstone, Evan S. Kane, Susan M. Natali, James T. Randerson, Merritt R. Turetsky, Ellen Whitman, Elizabeth Wiggins, and Brendan M. Rogers
Biogeosciences, 20, 2785–2804, https://doi.org/10.5194/bg-20-2785-2023, https://doi.org/10.5194/bg-20-2785-2023, 2023
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Here we developed a new burned-area detection algorithm between 2001–2019 across Alaska and Canada at 500 m resolution. We estimate 2.37 Mha burned annually between 2001–2019 over the domain, emitting 79.3 Tg C per year, with a mean combustion rate of 3.13 kg C m−2. We found larger-fire years were generally associated with greater mean combustion. The burned-area and combustion datasets described here can be used for local- to continental-scale applications of boreal fire science.
V. Rachel Chimuka, Claude-Michel Nzotungicimpaye, and Kirsten Zickfeld
Biogeosciences, 20, 2283–2299, https://doi.org/10.5194/bg-20-2283-2023, https://doi.org/10.5194/bg-20-2283-2023, 2023
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We propose a new method to quantify carbon cycle feedbacks under negative CO2 emissions. Our method isolates the lagged carbon cycle response to preceding positive emissions from the response to negative emissions. Our findings suggest that feedback parameters calculated with the novel approach are larger than those calculated with the conventional approach whereby carbon cycle inertia is not corrected for, with implications for the effectiveness of carbon dioxide removal in reducing CO2 levels.
Marcus Breil, Annabell Weber, and Joaquim G. Pinto
Biogeosciences, 20, 2237–2250, https://doi.org/10.5194/bg-20-2237-2023, https://doi.org/10.5194/bg-20-2237-2023, 2023
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A promising strategy for mitigating burdens of heat extremes in Europe is to replace dark coniferous forests with brighter deciduous forests. The consequence of this would be reduced absorption of solar radiation, which should reduce the intensities of heat periods. In this study, we show that deciduous forests have a certain cooling effect on heat period intensities in Europe. However, the magnitude of the temperature reduction is quite small.
Gesche Blume-Werry, Jonatan Klaminder, Eveline J. Krab, and Sylvain Monteux
Biogeosciences, 20, 1979–1990, https://doi.org/10.5194/bg-20-1979-2023, https://doi.org/10.5194/bg-20-1979-2023, 2023
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Northern soils store a lot of carbon. Most research has focused on how this carbon storage is regulated by cold temperatures. However, it is soil organisms, from minute bacteria to large earthworms, that decompose the organic material. Novel soil organisms from further south could increase decomposition rates more than climate change does and lead to carbon losses. We therefore advocate for including soil organisms when predicting the fate of soil functions in warming northern ecosystems.
Koramanghat Unnikrishnan Jayakrishnan and Govindasamy Bala
Biogeosciences, 20, 1863–1877, https://doi.org/10.5194/bg-20-1863-2023, https://doi.org/10.5194/bg-20-1863-2023, 2023
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Afforestation and reducing fossil fuel emissions are two important mitigation strategies to reduce the amount of global warming. Our work shows that reducing fossil fuel emissions is relatively more effective than afforestation for the same amount of carbon removed from the atmosphere. However, understanding of the processes that govern the biophysical effects of afforestation should be improved before considering our results for climate policy.
Jens Hartmann, Niels Suitner, Carl Lim, Julieta Schneider, Laura Marín-Samper, Javier Arístegui, Phil Renforth, Jan Taucher, and Ulf Riebesell
Biogeosciences, 20, 781–802, https://doi.org/10.5194/bg-20-781-2023, https://doi.org/10.5194/bg-20-781-2023, 2023
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CO2 can be stored in the ocean via increasing alkalinity of ocean water. Alkalinity can be created via dissolution of alkaline materials, like limestone or soda. Presented research studies boundaries for increasing alkalinity in seawater. The best way to increase alkalinity was found using an equilibrated solution, for example as produced from reactors. Adding particles for dissolution into seawater on the other hand produces the risk of losing alkalinity and degassing of CO2 to the atmosphere.
Damian L. Arévalo-Martínez, Amir Haroon, Hermann W. Bange, Ercan Erkul, Marion Jegen, Nils Moosdorf, Jens Schneider von Deimling, Christian Berndt, Michael Ernst Böttcher, Jasper Hoffmann, Volker Liebetrau, Ulf Mallast, Gudrun Massmann, Aaron Micallef, Holly A. Michael, Hendrik Paasche, Wolfgang Rabbel, Isaac Santos, Jan Scholten, Katrin Schwalenberg, Beata Szymczycha, Ariel T. Thomas, Joonas J. Virtasalo, Hannelore Waska, and Bradley A. Weymer
Biogeosciences, 20, 647–662, https://doi.org/10.5194/bg-20-647-2023, https://doi.org/10.5194/bg-20-647-2023, 2023
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Groundwater flows at the land–ocean transition and the extent of freshened groundwater below the seafloor are increasingly relevant in marine sciences, both because they are a highly uncertain term of biogeochemical budgets and due to the emerging interest in the latter as a resource. Here, we discuss our perspectives on future research directions to better understand land–ocean connectivity through groundwater and its potential responses to natural and human-induced environmental changes.
Morgan Sparey, Peter Cox, and Mark S. Williamson
Biogeosciences, 20, 451–488, https://doi.org/10.5194/bg-20-451-2023, https://doi.org/10.5194/bg-20-451-2023, 2023
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Accurate climate models are vital for mitigating climate change; however, projections often disagree. Using Köppen–Geiger bioclimate classifications we show that CMIP6 climate models agree well on the fraction of global land surface that will change classification per degree of global warming. We find that 13 % of land will change climate per degree of warming from 1 to 3 K; thus, stabilising warming at 1.5 rather than 2 K would save over 7.5 million square kilometres from bioclimatic change.
Huanhuan Wang, Chao Yue, and Sebastiaan Luyssaert
Biogeosciences, 20, 75–92, https://doi.org/10.5194/bg-20-75-2023, https://doi.org/10.5194/bg-20-75-2023, 2023
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This study provided a synthesis of three influential methods to quantify afforestation impact on surface temperature. Results showed that actual effect following afforestation was highly dependent on afforestation fraction. When full afforestation is assumed, the actual effect approaches the potential effect. We provided evidence the afforestation faction is a key factor in reconciling different methods and emphasized that it should be considered for surface cooling impacts in policy evaluation.
Ryan S. Padrón, Lukas Gudmundsson, Laibao Liu, Vincent Humphrey, and Sonia I. Seneviratne
Biogeosciences, 19, 5435–5448, https://doi.org/10.5194/bg-19-5435-2022, https://doi.org/10.5194/bg-19-5435-2022, 2022
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The answer to how much carbon land ecosystems are projected to remove from the atmosphere until 2100 is different for each Earth system model. We find that differences across models are primarily explained by the annual land carbon sink dependence on temperature and soil moisture, followed by the dependence on CO2 air concentration, and by average climate conditions. Our insights on why each model projects a relatively high or low land carbon sink can help to reduce the underlying uncertainty.
Julian Gutt, Stefanie Arndt, David Keith Alan Barnes, Horst Bornemann, Thomas Brey, Olaf Eisen, Hauke Flores, Huw Griffiths, Christian Haas, Stefan Hain, Tore Hattermann, Christoph Held, Mario Hoppema, Enrique Isla, Markus Janout, Céline Le Bohec, Heike Link, Felix Christopher Mark, Sebastien Moreau, Scarlett Trimborn, Ilse van Opzeeland, Hans-Otto Pörtner, Fokje Schaafsma, Katharina Teschke, Sandra Tippenhauer, Anton Van de Putte, Mia Wege, Daniel Zitterbart, and Dieter Piepenburg
Biogeosciences, 19, 5313–5342, https://doi.org/10.5194/bg-19-5313-2022, https://doi.org/10.5194/bg-19-5313-2022, 2022
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Long-term ecological observations are key to assess, understand and predict impacts of environmental change on biotas. We present a multidisciplinary framework for such largely lacking investigations in the East Antarctic Southern Ocean, combined with case studies, experimental and modelling work. As climate change is still minor here but is projected to start soon, the timely implementation of this framework provides the unique opportunity to document its ecological impacts from the very onset.
Daniel François, Adina Paytan, Olga Maria Oliveira de Araújo, Ricardo Tadeu Lopes, and Cátia Fernandes Barbosa
Biogeosciences, 19, 5269–5285, https://doi.org/10.5194/bg-19-5269-2022, https://doi.org/10.5194/bg-19-5269-2022, 2022
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Our analysis revealed that under the two most conservative acidification projections foraminifera assemblages did not display considerable changes. However, a significant decrease in species richness was observed when pH decreases to 7.7 pH units, indicating adverse effects under high-acidification scenarios. A micro-CT analysis revealed that calcified tests of Archaias angulatus were of lower density in low pH, suggesting no acclimation capacity for this species.
Leander Moesinger, Ruxandra-Maria Zotta, Robin van der Schalie, Tracy Scanlon, Richard de Jeu, and Wouter Dorigo
Biogeosciences, 19, 5107–5123, https://doi.org/10.5194/bg-19-5107-2022, https://doi.org/10.5194/bg-19-5107-2022, 2022
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The standardized vegetation optical depth index (SVODI) can be used to monitor the vegetation condition, such as whether the vegetation is unusually dry or wet. SVODI has global coverage, spans the past 3 decades and is derived from multiple spaceborne passive microwave sensors of that period. SVODI is based on a new probabilistic merging method that allows the merging of normally distributed data even if the data are not gap-free.
Rebecca M. Varney, Sarah E. Chadburn, Eleanor J. Burke, and Peter M. Cox
Biogeosciences, 19, 4671–4704, https://doi.org/10.5194/bg-19-4671-2022, https://doi.org/10.5194/bg-19-4671-2022, 2022
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Soil carbon is the Earth’s largest terrestrial carbon store, and the response to climate change represents one of the key uncertainties in obtaining accurate global carbon budgets required to successfully militate against climate change. The ability of climate models to simulate present-day soil carbon is therefore vital. This study assesses soil carbon simulation in the latest ensemble of models which allows key areas for future model development to be identified.
Laurent Bopp, Olivier Aumont, Lester Kwiatkowski, Corentin Clerc, Léonard Dupont, Christian Ethé, Thomas Gorgues, Roland Séférian, and Alessandro Tagliabue
Biogeosciences, 19, 4267–4285, https://doi.org/10.5194/bg-19-4267-2022, https://doi.org/10.5194/bg-19-4267-2022, 2022
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The impact of anthropogenic climate change on the biological production of phytoplankton in the ocean is a cause for concern because its evolution could affect the response of marine ecosystems to climate change. Here, we identify biological N fixation and its response to future climate change as a key process in shaping the future evolution of marine phytoplankton production. Our results show that further study of how this nitrogen fixation responds to environmental change is essential.
Negar Vakilifard, Richard G. Williams, Philip B. Holden, Katherine Turner, Neil R. Edwards, and David J. Beerling
Biogeosciences, 19, 4249–4265, https://doi.org/10.5194/bg-19-4249-2022, https://doi.org/10.5194/bg-19-4249-2022, 2022
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To remain within the Paris climate agreement, there is an increasing need to develop and implement carbon capture and sequestration techniques. The global climate benefits of implementing negative emission technologies over the next century are assessed using an Earth system model covering a wide range of plausible climate states. In some model realisations, there is continued warming after emissions cease. This continued warming is avoided if negative emissions are incorporated.
Marco Reale, Gianpiero Cossarini, Paolo Lazzari, Tomas Lovato, Giorgio Bolzon, Simona Masina, Cosimo Solidoro, and Stefano Salon
Biogeosciences, 19, 4035–4065, https://doi.org/10.5194/bg-19-4035-2022, https://doi.org/10.5194/bg-19-4035-2022, 2022
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Future projections under the RCP8.5 and RCP4.5 emission scenarios of the Mediterranean Sea biogeochemistry at the end of the 21st century show different levels of decline in nutrients, oxygen and biomasses and an acidification of the water column. The signal intensity is stronger under RCP8.5 and in the eastern Mediterranean. Under RCP4.5, after the second half of the 21st century, biogeochemical variables show a recovery of the values observed at the beginning of the investigated period.
Charly A. Moras, Lennart T. Bach, Tyler Cyronak, Renaud Joannes-Boyau, and Kai G. Schulz
Biogeosciences, 19, 3537–3557, https://doi.org/10.5194/bg-19-3537-2022, https://doi.org/10.5194/bg-19-3537-2022, 2022
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This research presents the first laboratory results of quick and hydrated lime dissolution in natural seawater. These two minerals are of great interest for ocean alkalinity enhancement, a strategy aiming to decrease atmospheric CO2 concentrations. Following the dissolution of these minerals, we identified several hurdles and presented ways to avoid them or completely negate them. Finally, we proceeded to various simulations in today’s oceans to implement the strategy at its highest potential.
Taraka Davies-Barnard, Sönke Zaehle, and Pierre Friedlingstein
Biogeosciences, 19, 3491–3503, https://doi.org/10.5194/bg-19-3491-2022, https://doi.org/10.5194/bg-19-3491-2022, 2022
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Biological nitrogen fixation is the largest natural input of new nitrogen onto land. Earth system models mainly represent global total terrestrial biological nitrogen fixation within observational uncertainties but overestimate tropical fixation. The model range of increase in biological nitrogen fixation in the SSP3-7.0 scenario is 3 % to 87 %. While biological nitrogen fixation is a key source of new nitrogen, its predictive power for net primary productivity in models is limited.
Niel Verbrigghe, Niki I. W. Leblans, Bjarni D. Sigurdsson, Sara Vicca, Chao Fang, Lucia Fuchslueger, Jennifer L. Soong, James T. Weedon, Christopher Poeplau, Cristina Ariza-Carricondo, Michael Bahn, Bertrand Guenet, Per Gundersen, Gunnhildur E. Gunnarsdóttir, Thomas Kätterer, Zhanfeng Liu, Marja Maljanen, Sara Marañón-Jiménez, Kathiravan Meeran, Edda S. Oddsdóttir, Ivika Ostonen, Josep Peñuelas, Andreas Richter, Jordi Sardans, Páll Sigurðsson, Margaret S. Torn, Peter M. Van Bodegom, Erik Verbruggen, Tom W. N. Walker, Håkan Wallander, and Ivan A. Janssens
Biogeosciences, 19, 3381–3393, https://doi.org/10.5194/bg-19-3381-2022, https://doi.org/10.5194/bg-19-3381-2022, 2022
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In subarctic grassland on a geothermal warming gradient, we found large reductions in topsoil carbon stocks, with carbon stocks linearly declining with warming intensity. Most importantly, however, we observed that soil carbon stocks stabilised within 5 years of warming and remained unaffected by warming thereafter, even after > 50 years of warming. Moreover, in contrast to the large topsoil carbon losses, subsoil carbon stocks remained unaffected after > 50 years of soil warming.
Roberto Pilli, Ramdane Alkama, Alessandro Cescatti, Werner A. Kurz, and Giacomo Grassi
Biogeosciences, 19, 3263–3284, https://doi.org/10.5194/bg-19-3263-2022, https://doi.org/10.5194/bg-19-3263-2022, 2022
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To become carbon neutral by 2050, the European Union (EU27) forest C sink should increase to −450 Mt CO2 yr-1. Our study highlights that under current management practices (i.e. excluding any policy scenario) the forest C sink of the EU27 member states and the UK may decrease to about −250 Mt CO2eq yr-1 in 2050. The expected impacts of future climate change, however, add a considerable uncertainty, potentially nearly doubling or halving the sink associated with forest management.
Johnathan Daniel Maxey, Neil David Hartstein, Aazani Mujahid, and Moritz Müller
Biogeosciences, 19, 3131–3150, https://doi.org/10.5194/bg-19-3131-2022, https://doi.org/10.5194/bg-19-3131-2022, 2022
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Deep coastal inlets are important sites for regulating land-based organic pollution before it enters coastal oceans. This study focused on how large climate forces, rainfall, and river flow impact organic loading and oxygen conditions in a coastal inlet in Tasmania. Increases in rainfall were linked to higher organic loading and lower oxygen in basin waters. Finally we observed a significant correlation between the Southern Annular Mode and oxygen concentrations in the system's basin waters.
Guang Gao, Tifeng Wang, Jiazhen Sun, Xin Zhao, Lifang Wang, Xianghui Guo, and Kunshan Gao
Biogeosciences, 19, 2795–2804, https://doi.org/10.5194/bg-19-2795-2022, https://doi.org/10.5194/bg-19-2795-2022, 2022
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After conducting large-scale deck-incubation experiments, we found that seawater acidification (SA) increased primary production (PP) in coastal waters but reduced it in pelagic zones, which is mainly regulated by local pH, light intensity, salinity, and community structure. In future oceans, SA combined with decreased upward transports of nutrients may synergistically reduce PP in pelagic zones.
Joko Sampurno, Valentin Vallaeys, Randy Ardianto, and Emmanuel Hanert
Biogeosciences, 19, 2741–2757, https://doi.org/10.5194/bg-19-2741-2022, https://doi.org/10.5194/bg-19-2741-2022, 2022
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This study is the first assessment to evaluate the interactions between river discharges, tides, and storm surges and how they can drive compound flooding in the Kapuas River delta. We successfully created a realistic hydrodynamic model whose domain covers the land–sea continuum using a wetting–drying algorithm in a data-scarce environment. We then proposed a new method to delineate compound flooding hazard zones along the river channels based on the maximum water level profiles.
Svenja Dobbert, Roland Pape, and Jörg Löffler
Biogeosciences, 19, 1933–1958, https://doi.org/10.5194/bg-19-1933-2022, https://doi.org/10.5194/bg-19-1933-2022, 2022
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Understanding how vegetation might respond to climate change is especially important in arctic–alpine ecosystems, where major shifts in shrub growth have been observed. We studied how such changes come to pass and how future changes might look by measuring hourly variations in the stem diameter of dwarf shrubs from one common species. From these data, we are able to discern information about growth mechanisms and can thus show the complexity of shrub growth and micro-environment relations.
Jody Daniel, Rebecca C. Rooney, and Derek T. Robinson
Biogeosciences, 19, 1547–1570, https://doi.org/10.5194/bg-19-1547-2022, https://doi.org/10.5194/bg-19-1547-2022, 2022
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The threat posed by climate change to prairie pothole wetlands is well documented, but gaps remain in our ability to make meaningful predictions about how prairie pothole wetlands will respond. We integrate aspects of topography, land cover/land use and climate to model the permanence class of tens of thousands of wetlands at the western edge of the Prairie Pothole Region.
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