Carbon cycling in a warming world: a deglacial test case
Lead Research Organisation:
University of Bristol
Department Name: Earth Sciences
Abstract
Projections of future climate change require us to understand the interactions between carbon and its main reservoirs, including the large natural exchanges between ocean, land and atmosphere. Studies have also shown that uncertainties in modelling the carbon cycle are as important as uncertainties in modelling the physical climate system. Thus it is vital that we develop a better quantitative understanding. The natural component of the carbon cycle has already been significantly perturbed today, so studying the natural processes before human interventions is an important additional test of our knowledge and understanding. This is particularly true when there were abrupt perturbations on the climate system that occurred on human-relevant timescales. A prime target is the transition out of the glacial period, some 20,000 years ago. The transition saw global temperatures increase by ~ 3-5C, sea level rise by 120m and atmospheric pCO2 increase by ~100ppmV. Importantly, a large portion of these changes occurred in rapid events which overprinted the long term deglacial transition.
We still do not fully understand how CO2 levels in the atmosphere increased over this time although processes that alter the balance of carbon between the ocean, land and the atmosphere are certainly critical. Indeed, the leading hypothesis to explain the major rise in atmospheric CO2 calls upon release of carbon from the deep ocean that accumulated from the decay of organic matter as it rains down through to the ocean's depths. At the same time changes in the terrestrial biosphere are thought to have contributed through processes including permafrost melting. This link between biological productivity and the exchange of carbon between its reservoirs is a timely topic given concern over the fate of anthropogenic carbon emissions - including ocean acidification and suggestions of long-term excess storage of carbon in the deep sea. However recent studies have provided data that contradict this view of carbon storage and exchange. Evidence has pointed towards climatically-triggered release of geologically-held carbon. The solid Earth contains vast reservoirs of carbon, so small changes in release have the potential to be important to the carbon budget. If release of geologic carbon is indeed sensitive to changes in the climate system, then this process may also be triggered under future climate scenarios. Constraining the potential impact of geologic carbon released in the past has the potential to provide critical new information in projecting future change.
The interdisciplinary project team proposes an ambitious programme combining field work, geochemical analyses and integrated modelling to provide specific tests of the competing hypotheses that have been used to explain the rising CO2 levels at the end of the glacial period. We will particularly focus on using radiocarbon to help diagnose the distinct sources of carbon. New data will be based on geochemical analyses on precisely dated deep-sea coral skeletons collected from locations which are key to these tests. We will mount the first Remotely Operated Vehicle research expedition to the Eastern Equatorial Pacific dedicated to systematic collections of corals from depths where release of geological carbon is hypothesised to have occurred. Our second focus will be on the North Atlantic (samples in hand) where changes in ocean circulation and linkages to isolated basins may have played a key role in releasing carbon from the deep ocean. We will integrate these data with existing knowledge and use them in conjunction with climate modelling (including intermediate complexity models and state of the art General Circulation Models) to explore which processes are most important to the Earth system in a warming world. We will also be well placed to formulate a broad synthesis of the processes controlling the carbon cycle during the most pronounced rapid warming period of recent Earth history.
We still do not fully understand how CO2 levels in the atmosphere increased over this time although processes that alter the balance of carbon between the ocean, land and the atmosphere are certainly critical. Indeed, the leading hypothesis to explain the major rise in atmospheric CO2 calls upon release of carbon from the deep ocean that accumulated from the decay of organic matter as it rains down through to the ocean's depths. At the same time changes in the terrestrial biosphere are thought to have contributed through processes including permafrost melting. This link between biological productivity and the exchange of carbon between its reservoirs is a timely topic given concern over the fate of anthropogenic carbon emissions - including ocean acidification and suggestions of long-term excess storage of carbon in the deep sea. However recent studies have provided data that contradict this view of carbon storage and exchange. Evidence has pointed towards climatically-triggered release of geologically-held carbon. The solid Earth contains vast reservoirs of carbon, so small changes in release have the potential to be important to the carbon budget. If release of geologic carbon is indeed sensitive to changes in the climate system, then this process may also be triggered under future climate scenarios. Constraining the potential impact of geologic carbon released in the past has the potential to provide critical new information in projecting future change.
The interdisciplinary project team proposes an ambitious programme combining field work, geochemical analyses and integrated modelling to provide specific tests of the competing hypotheses that have been used to explain the rising CO2 levels at the end of the glacial period. We will particularly focus on using radiocarbon to help diagnose the distinct sources of carbon. New data will be based on geochemical analyses on precisely dated deep-sea coral skeletons collected from locations which are key to these tests. We will mount the first Remotely Operated Vehicle research expedition to the Eastern Equatorial Pacific dedicated to systematic collections of corals from depths where release of geological carbon is hypothesised to have occurred. Our second focus will be on the North Atlantic (samples in hand) where changes in ocean circulation and linkages to isolated basins may have played a key role in releasing carbon from the deep ocean. We will integrate these data with existing knowledge and use them in conjunction with climate modelling (including intermediate complexity models and state of the art General Circulation Models) to explore which processes are most important to the Earth system in a warming world. We will also be well placed to formulate a broad synthesis of the processes controlling the carbon cycle during the most pronounced rapid warming period of recent Earth history.
Planned Impact
Beyond the scientific community, we have identified five distinct end-user groups. Through the arc of the project we will continue to seek out additional opportunities to maximize the impact of our research.
a) Galápagos National Park and INOCAR: Our proposed research sites will explore the deep submarine flanks of the Galápagos islands and platform (~3500-500m), many of which have never been observed or sampled, so the proposed study will provide key data that will enhance the conservation efforts of the Charles Darwin Research Station and Galápagos National Park. Data from the cruise will be provided to INOCAR and the Ecuadorian government to help with the design of new limits for marine protected areas in the Galápagos (see letters of support). Part of our broader impacts effort will be devoted to raising awareness of the importance of the sub-photic benthic communities to the maintenance of the overall Galápagos ecosystem.
b) General Public - Project Website and Public Lectures and Events: Our project provides an excellent opportunity for public engagement regarding the protection of deep marine ecosystems, the carbon cycle and associated climate change. This effort will be linked with existing and new outreach websites. We will publicise our research through public talks, Facebook and Twitter, providing links to the website and our latest talks, press releases, and papers. Results will also be posted on the websites of participant organisations, e.g. through the Cabot Institute at UoB.
c) Undergraduates: Undergraduate students will be engaged directly in the project through hands-on laboratory and modelling expertise, helping them to develop a passion for scientific endeavour, and a deep knowledge of the research field. Summer projects and final year projects provide a great opportunity for advisors and students to integrate education and research beyond the classroom, advance discovery and understanding, while providing training on solving scientific problems and laboratory skills. Where possible, undergraduates will be included in the field program. Major findings will also be posted on the UoB Departmental Facebook pages and included in lecture material at UoB and in the departments of collaborating Universities, allowing the wider undergraduate community to maintain awareness of cutting-edge research activities.
d) Training and mentoring of two PDRAs: This project will enhance the career development of two PDRAs. PIs LFR and PV have excellent track records in actively training and advising postdoctoral scholars.
e) Supporting Women in STEM: The proposal supports a mid-career female investigator who will provide mentorship and role models for junior women in STEM subjects. We will include sections on our websites that touch on how women provide leadership in STEM subjects, from being Chief Scientist on a research cruise, to leading research teams as well as the paths taken to get here. Efforts will be made to include female undergraduates in the project through direct internships and through outreach presentations. Impact will be assessed by website traffic and event attendance.
a) Galápagos National Park and INOCAR: Our proposed research sites will explore the deep submarine flanks of the Galápagos islands and platform (~3500-500m), many of which have never been observed or sampled, so the proposed study will provide key data that will enhance the conservation efforts of the Charles Darwin Research Station and Galápagos National Park. Data from the cruise will be provided to INOCAR and the Ecuadorian government to help with the design of new limits for marine protected areas in the Galápagos (see letters of support). Part of our broader impacts effort will be devoted to raising awareness of the importance of the sub-photic benthic communities to the maintenance of the overall Galápagos ecosystem.
b) General Public - Project Website and Public Lectures and Events: Our project provides an excellent opportunity for public engagement regarding the protection of deep marine ecosystems, the carbon cycle and associated climate change. This effort will be linked with existing and new outreach websites. We will publicise our research through public talks, Facebook and Twitter, providing links to the website and our latest talks, press releases, and papers. Results will also be posted on the websites of participant organisations, e.g. through the Cabot Institute at UoB.
c) Undergraduates: Undergraduate students will be engaged directly in the project through hands-on laboratory and modelling expertise, helping them to develop a passion for scientific endeavour, and a deep knowledge of the research field. Summer projects and final year projects provide a great opportunity for advisors and students to integrate education and research beyond the classroom, advance discovery and understanding, while providing training on solving scientific problems and laboratory skills. Where possible, undergraduates will be included in the field program. Major findings will also be posted on the UoB Departmental Facebook pages and included in lecture material at UoB and in the departments of collaborating Universities, allowing the wider undergraduate community to maintain awareness of cutting-edge research activities.
d) Training and mentoring of two PDRAs: This project will enhance the career development of two PDRAs. PIs LFR and PV have excellent track records in actively training and advising postdoctoral scholars.
e) Supporting Women in STEM: The proposal supports a mid-career female investigator who will provide mentorship and role models for junior women in STEM subjects. We will include sections on our websites that touch on how women provide leadership in STEM subjects, from being Chief Scientist on a research cruise, to leading research teams as well as the paths taken to get here. Efforts will be made to include female undergraduates in the project through direct internships and through outreach presentations. Impact will be assessed by website traffic and event attendance.
Organisations
- University of Bristol (Lead Research Organisation)
- Woods Hole Oceanographic Institution (Collaboration, Project Partner)
- University of California, Santa Barbara (Collaboration)
- Nanjing University (NJU) (Collaboration)
- UNIVERSITY OF ESSEX (Collaboration)
- Princeton University (Project Partner)
- University of Southampton (Project Partner)
Publications
Kershaw J
(2023)
Ba/Ca of stylasterid coral skeletons records dissolved seawater barium concentrations
in Chemical Geology
Wang M
(2022)
The mineralization and early diagenesis of deep-sea coral Madrepora oculata
in Chemical Geology
Armstrong E
(2022)
Identifying the mechanisms of DO-scale oscillations in a GCM: a salt oscillator triggered by the Laurentide ice sheet
in Climate Dynamics
Snoll B
(2022)
Effect of orographic gravity wave drag on Northern Hemisphere climate in transient simulations of the last deglaciation
in Climate Dynamics
De Carvalho Ferreira M
(2022)
Spatial and temporal distribution of cold-water corals in the Northeast Atlantic Ocean over the last 150 thousand years
in Deep Sea Research Part I: Oceanographic Research Papers
Samperiz A
(2020)
Stylasterid corals: A new paleotemperature archive
in Earth and Planetary Science Letters
Stewart J
(2020)
Refining trace metal temperature proxies in cold-water scleractinian and stylasterid corals
in Earth and Planetary Science Letters
Wilson D
(2020)
Sea-ice control on deglacial lower cell circulation changes recorded by Drake Passage deep-sea corals
in Earth and Planetary Science Letters
Sun Y
(2023)
Iodine-to-calcium ratios in deep-sea scleractinian and bamboo corals
in Frontiers in Marine Science
Liu Q
(2023)
Reinterpreting radiocarbon records in bamboo corals - New insights from the tropical North Atlantic
in Geochimica et Cosmochimica Acta
Armstrong E
(2019)
Reassessing the Value of Regional Climate Modeling Using Paleoclimate Simulations
in Geophysical Research Letters
Gray W
(2020)
Wind-Driven Evolution of the North Pacific Subpolar Gyre Over the Last Deglaciation
in Geophysical Research Letters
Stewart J
(2020)
NIST RM 8301 Boron Isotopes in Marine Carbonate (Simulated Coral and Foraminifera Solutions): Inter-laboratory d 11 B and Trace Element Ratio Value Assignment
in Geostandards and Geoanalytical Research
Allen J
(2020)
Global vegetation patterns of the past 140,000 years
in Journal of Biogeography
Li T
(2023)
Enhanced subglacial discharge from Antarctica during meltwater pulse 1A.
in Nature communications
Chen T
(2020)
Persistently well-ventilated intermediate-depth ocean through the last deglaciation
in Nature Geoscience
Chen T
(2023)
Radiocarbon evidence for the stability of polar ocean overturning during the Holocene
in Nature Geoscience
Stewart J
(2021)
Productivity and Dissolved Oxygen Controls on the Southern Ocean Deep-Sea Benthos During the Antarctic Cold Reversal
in Paleoceanography and Paleoclimatology
Beisel E
(2023)
Climate Induced Thermocline Aging and Ventilation in the Eastern Atlantic Over the Last 32,000 Years
in Paleoceanography and Paleoclimatology
Hendry K
(2019)
The biogeochemical impact of glacial meltwater from Southwest Greenland
in Progress in Oceanography
Izumi K
(2023)
Global footprints of dansgaard-oeschger oscillations in a GCM
in Quaternary Science Reviews
Li T
(2020)
Rapid shifts in circulation and biogeochemistry of the Southern Ocean during deglacial carbon cycle events.
in Science advances
Armstrong E
(2020)
Author Correction: A simulated Northern Hemisphere terrestrial climate dataset for the past 60,000 years.
in Scientific data
Armstrong E
(2019)
A simulated Northern Hemisphere terrestrial climate dataset for the past 60,000 years.
in Scientific data
Stewart J
(2023)
Arctic and Antarctic forcing of ocean interior warming during the last deglaciation
in Scientific Reports
Stewart JA
(2022)
Stylasterid corals build aragonite skeletons in undersaturated water despite low pH at the site of calcification.
in Scientific reports
Description | The project has focussed on two main areas so far: (a) Increasing the spatial and temporal resolution of deglacial radiocarbon records. We have established that the low latitude Atlantic and Pacific oceans exhibited similar radiocarbon patterns during deglaciation, and that their geochemical composition was also similar to the Southern Ocean. These findings are suggestive of a Southern Ocean source feeding the low latitude oceans. This work has been published in Nature Geoscience. We have carried out dating work on corals from the Greenland Margin and Orphan Knoll. Whilst there are deglacial corals on Orphan Knoll, the oldest samples from Greenland Margin extend back to the early Holocene, potentially reflecting the melt back of the ices sheets, and sealevel rise. Preliminary work hints at large environmental changes coming out of the Little Ice Age. (b) Compiling and increasing data from the Last Glacial Maximum (LGM) as a reference for modelling and interpretation of the deglaciation. Within these data we have established a distinct shift in Atlantic circulation within the LGM which would not be resolvable in sedimentary records. Planning of the research expedition to the Eastern Equatorial Pacific is underway. It was originally scheduled for January 2021, but was delayed by COVID. It was scheduled for January 2022, but again postponed for COVID. We now hope to be able to use a US ship in April 2023. I will be applying for a funding extension for the work that will need to take place to carry out the expedition and subsequent work which will occur after the current project end date. |
Exploitation Route | These data will be of value to climate modelers and paleoclimate specialists, as well as those interested in the development of deep sea ecosystems. |
Sectors | Education,Environment |
Description | The data are being included in outreach talks by the team, thus our science is reaching a wide audience within the general public. |
First Year Of Impact | 2019 |
Sector | Education,Environment |
Impact Types | Cultural,Societal |
Description | Dan Fornari - WHOI |
Organisation | Woods Hole Oceanographic Institution |
Country | United States |
Sector | Charity/Non Profit |
PI Contribution | We will provide collaborative access to the research expedition |
Collaborator Contribution | Fornari will form part of the expedition team bringing expertise in mapping and imaging |
Impact | No outcomes yet, although papers submitted. Multidiscplinary - marine geology, oceanography, geochemistry |
Start Year | 2015 |
Description | Mathis Hain - UC Santa Barbara |
Organisation | University of California, Santa Barbara |
Country | United States |
Sector | Academic/University |
PI Contribution | Observations and analyses to contribute to modelling |
Collaborator Contribution | UCSB will use modelling to test observations and ideas from the proposal |
Impact | Observations and modelling. A paper has been submitted, but yet to receive reviews. |
Start Year | 2019 |
Description | Nanjing University |
Organisation | Nanjing University (NJU) |
Country | China |
Sector | Academic/University |
PI Contribution | Hosting 2 Nanjing University PhD students as visiting students at Bristol. Exchange of ideas. |
Collaborator Contribution | exchange of ideas and papers |
Impact | Continued exchange of ideas and papers since Dr Tianyu Chen left his post doc at Bristol to take up a position at Nanjing University. |
Start Year | 2017 |
Description | University of Essex |
Organisation | University of Essex |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | U. of Essex providing expertise in coral taxonomy and access to samples |
Collaborator Contribution | U of Bristol providing samples, access to research cruises and geochemical insights. |
Impact | The formal collaboration occurred with the start of this funding |
Start Year | 2018 |
Description | Colloquium at Lamont Doherty Earth Observatory |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Colloquium at LDEO |
Year(s) Of Engagement Activity | 2022 |
Description | Herdman Symposium |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Undergraduate students |
Results and Impact | Seminar as part of the Herman Symposium organised by Undergradute Students at the University of Liverpool open to public. |
Year(s) Of Engagement Activity | 2020 |
Description | Primary School Talk |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Schools |
Results and Impact | Engagement with primary school about the deep oceans |
Year(s) Of Engagement Activity | 2021 |
Description | Public talk - Boston Aquarium |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Public/other audiences |
Results and Impact | Large publich outreach talk 'The Carlson Lecture' organised by MIT at the Boston Aquarium, also live streamed and available on line. |
Year(s) Of Engagement Activity | 2019 |
URL | https://www.youtube.com/watch?v=gVsv0Xn4YhQ |
Description | Talk at CEBIMAR |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Seminar at CEBIMAR, Brazil to project partners, and other reserachers at the Institution. |
Year(s) Of Engagement Activity | 2019 |
Description | Videos for teaching |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Undergraduate students |
Results and Impact | Team members, and wider members of the research group at Bristol prepared short videos on their research for an undergraduate course in Oceans and Climates. These videos allowed the students to hear about the journey of PhD students, and their active research during a period (covid) when the undergraduates could not directly engage with the wider university. |
Year(s) Of Engagement Activity | 2020 |