Dynamics of the Oligocene cryosphere: mid-to-high latitude climate variability and ice sheet stability

Lead Research Organisation: Imperial College London
Department Name: Earth Science and Engineering

Abstract

The sensitivity of global climate to increasing atmospheric carbon dioxide (CO2) levels is one of the biggest issues currently facing humanity. Quantifying the sensitivity of the Earth's climate system to changes in CO2 levels in the geologic past is one way of reducing the uncertainty in future climate predictions. If man-made (anthropogenic) CO2 emissions to the atmosphere follow projected rates, by 2100 concentrations will reach values not seen on Earth since the Oligocene epoch ~23 to 34 million years ago (Ma). Back then, geologists infer that Earth was warmer than today, featuring a genuinely green Greenland and a waxing and waning East Antarctic Ice Sheet (EAIS) that drove high amplitude sea level change (~40 m). These startling observations provide a powerful incentive to improve our understanding of the workings of that past climate system.

The focus of this proposal is on an important, but understudied, interval of time (~26 to 28 Ma) for which published palaeoclimate records indicate the biggest repeated (100 thousand-year time scale) changes in Antarctic ice volume and high-latitude temperatures of the entire Oligocene epoch. Our proposed study will generate geological data to both test this interpretation of Oligocene high-latitude climate instability and further elucidate the nature of ice-sheet and temperature variability. Validation of the existence of dynamic Antarctic ice sheets, however, would present a major scientific problem because numerical analysis of ice sheet behavior suggests that, in the absence of big changes in CO2 levels, a large Antarctic ice sheet should be stable once formed because of strong hysteresis properties associated with ice sheet geometry.

Several important questions are therefore raised:

1. How resilient were the early Antarctic ice sheets to CO2 change?
2. Do the numerical models give a false sense of the stability of both the Oligocene and, by extension, present day East Antarctic Ice Sheet?
3. Was Oligocene CO2 variability much greater than indicated in existing reconstructions?
4. Is it possible that ice sheets existed beyond Antarctica during the Oligocene?

The main factor that has limited progress in tackling these questions has been a lack of suitable sedimentary sections on which to work. We propose to exploit new deep-sea sediment archives recovered from the Antarctic and Newfoundland margins during Integrated Ocean Drilling Program Expeditions 318 and 342, respectively, on which our investigator team played significant roles (see Part 1, Case for Support). Our project will use (i) the Antarctic cores to test for the erosive products of dynamic behaviour (advance and retreat) on the East Antarctic margin, and (ii) the Newfoundland cores to test if high-latitude climatic conditions in the Northern Hemisphere were conducive to ice-sheet growth. Intriguingly, the drill cores from the Newfoundland margin contain abundant conspicuous angular sand sized lithic fragments that have been interpreted to be of ice-rafted origin-hinting at the presence of some form of nearby ice in the Oligocene. Our work will be accomplished through novel investigation of detrital isotope geochemistry on the Antarctic margin and application of organic geochemical temperature proxies in the high-latitude North Atlantic. Critical to our approach will be generation of high-resolution datasets that can be precisely dated and correlated to one another, as well as other high-resolution datasets around the globe.

Planned Impact

1. Who will benefit from this research?

This project will benefit the following specific users: Palaeoceanographers & Palaeoclimatologists; Climate and Cryosphere scientists; Earth System Scientists; the industrial hydrocarbon exploration sector of the UK economy; the wider community of scientists working on the problem of anthropogenic climate change; school children and the wider public interested in the exploration of the oceans and Earth.

2. How will they benefit from this research?

This project will make a significant scientific advancement towards understanding the stability of an interval in Earth's history when existing records suggest that Antarctic ice sheets underwent repeated large scale growth and retreat despite little apparent change in atmospheric carbon dioxide levels and the ice sheet stability predicted by numerical climate models. The records to be generated are from the Antarctic and Newfoundland margins in the Southern and North Atlantic Oceans, respectively, and will be of higher fidelity (time resolution) than those previously obtained for this interval. We will sample drillcores of sediments recovered from the deep ocean by Integrated Ocean Drilling Program Expeditions 318 (Bohaty, sedimentologist and van de Flierdt, inorganic geochemist) and 342 (Wilson, Co Chief Scientist). These sediments have unusually high rates of deposition and crucially, are well-suited, not only to record the terrestrial and marine imprint of high-latitude climate variability but also to the construction of these records with excellent age control (benthic stable isotope, palaeomagnetic and cyclostratigraphies). Improved knowledge of the stratigraphy of the Newfoundland sediment drifts and global glacial-interglacial cycles acquired during our project will also be used to improve the UK Industrial knowledge base that underpins techniques used to discover new petroleum reserves in deep-water settings.

3. What will be done to ensure that they benefit?

i) Our results will be made available for peer and public scrutiny by presentation in scientific meetings and publication in the
scientific literature.
ii) Follow-up dissemination to the wider public will be achieved in the first instance through media interviews to national and global news networks (eg., AP, Reuters); this is the most efficient channel for high impact and can ultimately result in spin-out feature articles (e.g., http://www.newscientist.com/issue/2661).
iii) Working with our Knowledge Exchange Officer, we will prepare summaries of important findings for press releases to new wires and postings on the University of Southampton and NOCS news websites (http://www.noc.soton.ac.uk/index.php).
iv) Rapid dissemination to the Earth System Science community during the course of the project will be achieved by presentations at international meetings and participation in workshops.
v) Meetings in Soton and Abingdon with Dr Andrew Davies (Neftex, UoS Ocean & Earth Sci departmental Stakeholder Advisory Board) to discuss the implications of our work for improving the knowledge base that underpins training in the key skill set used to discover new hydrocarbon reserves in deep-water settings.
vi) Our results will be incorporated into NOCS "Ocean & Earth" day activities used to enthuse young people in science and wider participation in Higher Education.
vii) We will leverage UK/NERC Impact from ANDRILL and IODP investment in high-profile science impact activities. For example, two dedicated scientific outreach professionals participated in IODP Exp 342 and Mr D. Brinkhuis produced and disseminated a series of 10 min-long video clips during the expedition and post-cruise plus a 20 min. documentary that debuted at Fall AGU 2012. Available online, these videos have already resulted in >27,750 viewings (25/6/13).

Publications

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Dziadek R (2019) Elevated geothermal surface heat flow in the Amundsen Sea Embayment, West Antarctica in Earth and Planetary Science Letters

 
Description This research project was focused on understanding the climate system during the early stages of the modern 'Icehouse' climate phase, which first developed during the Oligocene epoch following rapid global cooling and the onset of Antarctic glaciation at the Eocene-Oligocene Transition (EOT, 34 million years ago). Results point to a highly dynamic Antarctic ice-sheet that repeatedly advanced and retreated on orbital (20 to 400 thousand year) timescales. These oscillations are linked to carbonate dissolution cycles throughout the deep ocean basins, indicating a direct connection between high-latitude climate and ocean chemistry. In detail, the Imperial component of the project produced a large amount of new detrital neodymium isotope data from three different ODP and IODP sites in the Southern Ocean around the margins of the East Antarctic ice sheet (Maud Rise, Kerguelen Plateau, offshore Adelie Land). An abrupt change in sediment provenance is observed at all three locations across the EOT. The timing of the provenance change coincides with the onset of major Antarctic glaciation and supports the theory of rapid and continent-wide glaciation across the EOT as proposed by far-field records. High resolution records for the Oligocene target interval (~26-28 Ma) show that ice waxing and waning happened with a strong cyclicity, with the most pronounced glacial retreat on Antarctica occurring on the longer 400 kyr orbital cycle. Our results have important implications for the Oligocene carbon cycle, ocean temperature and past mechanisms of climate change. Integration and publication of the data sets collected by all partner institutions is ongoing.
Exploitation Route To inform policy on human-driven climate change.
Sectors Education,Environment

 
Description Ocean-ice Interaction in the Ross Sea during Past Warm Periods
Amount £25,152 (GBP)
Funding ID NE/R018219/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 04/2018 
End 12/2019
 
Description Royal Society International Exchange grant
Amount £11,650 (GBP)
Funding ID IE161090 
Organisation The Royal Society 
Sector Academic/University
Country United Kingdom
Start 03/2017 
End 02/2019
 
Description Authigenic and detrital Nd isotope analysis, USC, Howie Scher 
Organisation University of South Carolina
Country United States 
Sector Academic/University 
PI Contribution Authigenic and detrital Nd isotope analysis on several sites around the East Antarctic margin. Exchange on methodology.
Collaborator Contribution Authigenic and detrital Nd isotope analysis on several sites around the East Antarctic margin. Exchange on methodology.
Impact Close interaction with Howie Scher's laboratory in South Carolina, and a visit by PDRA Claire Huck, has let to a larger data set for the project than otherwise possible. Comparison of methodologies between USC and Imperial College London, led to important modifications of our analytical procedures that will be documented in a publication.
Start Year 2014
 
Description Evening lecture in Cardiff 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Sparked questions and discussion.
Year(s) Of Engagement Activity 2016
 
Description History of Antarctic drilling video 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Participated in filming for a video on the history of Antarctic drilling.
Year(s) Of Engagement Activity 2018
URL https://www.youtube.com/watch?v=GN9faSiGUZQ
 
Description IODP planning workshop, Sydney 2017 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact Australasian IODP Planning Workshop to develop proposals for research expeditions for the next phase of IODP drilling. Co-chaired the climate and ocean theme (plenary presentation and guidance and summary of discussions).
Year(s) Of Engagement Activity 2017
URL https://www.iodp.org/australasian-workshop-report-june-2017
 
Description MAGIC Elements 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Hundreds of under-12s visited the Imperial Festival stand on MAGIC Elements with their parents. They dressed up as scientists, learned about elements and isotopes, and even about how Antarctica once was a continent with palm trees at its shorelines.
Year(s) Of Engagement Activity 2018
URL https://www.imperial.ac.uk/news/185986/imperial-festival-transforms-under-12s-into-mini/
 
Description Media contact Grantham 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Part of a small group of Grantham affiliates that helps with media requests. My expertise is in the are of palaeoclimate and Antarctic ice sheets
Year(s) Of Engagement Activity 2016,2017,2018,2019
 
Description Ocean-ice interaction workshop, Hobart, 2017 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact This small workshop was aimed to bring together people from different communities to understand the sensitivity of the Antarctic ice sheet to marine climate change. Presentations on observations from the ocean,ice, solid earth were followed by an integration of all components. The key outcome of this workshop will be a review article in Reviews of Geophysics (confirmed).
Year(s) Of Engagement Activity 2017
 
Description PROCEED workshop 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Study participants or study members
Results and Impact >50 international scientist attended the PROCEED workshop (Expanding Frontiers of Scientific Drilling) in Vienna. I co-led the workshop discussion on expanding IODP science in the context of the IPCC.
Year(s) Of Engagement Activity 2019
 
Description Pint of Science 2018 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Outreach talk in a pub to explain science to the general public in a friendly environment.
Year(s) Of Engagement Activity 2018
URL https://pintofscience.co.uk/event/understanding-antarctica
 
Description Podcast interview 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact 1 hour interview for the forecast, a podcast about climate science and climate scientists. Long format interviews with Nature's editor for climate science, Michael White.
Year(s) Of Engagement Activity 2016
URL http://forecastpod.org/?s=tina+van+de+Flierdt
 
Description Twitter 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Tweets about climate change, Antarctica, women in science, STEM related topics and (Earth) Science in general.
Year(s) Of Engagement Activity 2014,2015,2016,2017,2018
 
Description UK IODP conference 2014 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact Keynote speaker at the UK IODP conference. Reported results of IODP Expedition 318 to date.

Great feedback on how successful this particular expedition was, and great discussions about the work done in my group.
Year(s) Of Engagement Activity 2014