CoolRhythms: the impact of ice volume and ocean circulation on Earth's Coolhouse climate beat
Lead Research Organisation:
University College London
Department Name: Earth Sciences
Abstract
Earth's changing climate is inexorably linked to the energy it receives from the Sun, which varies rhythmically, driven by the eccentricity, obliquity and precession of Earth's orbit. Earth redistributes this solar energy, sustaining warmer and cooler climate states that last for millions of years (Myr). The shifts between Earth's long-term climate states are caused by large changes in polar ice and greenhouse gasses. Over the last 40 million years, ice volume has played an important role in influencing Earth's climate. One of these climate states - the Coolhouse - captures when large ice sheets first formed at Earth's poles. The solar energy also drives a faster climate response, which beats in tune with these orbital variations. Even though the rhythmic energy that drives Earth's climate response has not changed, Earth's climate beat itself has not been stable through time. We currently do not understand what causes this. Through the CoolRhythms proposal, I will establish when and why these different beats in Earth's climate occur and explore if global warming could cause another change of climate beat in the future.
Two major ice growth events coincide with big transitions at the beginning and the middle of the Coolhouse word. Surprisingly, Earth's climate beat responded differently during these two important climatic transitions. About 34 Myr ago in the early Coolhouse, ice first formed on Antarctic ice as Earth shifted from a warm to cool climate transition and eccentricity was unchanged as the main driver of Earth's climate beat. The Earth cooled again in the mid-Coolhouse and gained more ice between 15 and 5 Myr ago, yet this time the climate beat changed from eccentricity to obliquity. Why Earth's climate changed its beat is an enigma, which I will investigate by:
1. Establishing Earth's exact climate beat during the early and mid-Coolhouse transitions;
2. Determining which processes caused Earth's climate beat to switch from eccentricity to obliquity;
3. Exploring if future warming could reverse this switch.
CoolRhythms will be hosted at UCL in collaboration with a network of world experts. To achieve my aims, I will combine data science with a novel targeted sampling approach that integrates stratigraphy and geochemistry to optimise information recovery. I will establish Earth's climate beat across the key transitions by filling gaps in our knowledge with new data from deep-sea microfossils and by resolving conflicting interpretations of existing records. I will develop software to characterise the climatic beat in the different records and then combine them to acquire a global view of climate. I will analyse the stable oxygen and carbon isotope and trace element composition of microfossils from deep-sea sediments, collected during IODP ocean drilling expeditions in all ocean basins. I will combine this geochemistry with the sedimentary composition to reconstruct high-resolution ice volume and ocean circulation patterns at the same scale as Earth's climate beat. I will also use modelling to test how the location of the ice growth affects the climate beat and whether an eccentricity driven beat could return in the future.
My approach will enable me to determine which Earth system feedback caused the differing climate beats during these transitions. Refining our understanding of how Earth's climate beat varied during warmer and cooler climate states will ultimately help understand how a warmer Earth may affect the variability of future climate.
Two major ice growth events coincide with big transitions at the beginning and the middle of the Coolhouse word. Surprisingly, Earth's climate beat responded differently during these two important climatic transitions. About 34 Myr ago in the early Coolhouse, ice first formed on Antarctic ice as Earth shifted from a warm to cool climate transition and eccentricity was unchanged as the main driver of Earth's climate beat. The Earth cooled again in the mid-Coolhouse and gained more ice between 15 and 5 Myr ago, yet this time the climate beat changed from eccentricity to obliquity. Why Earth's climate changed its beat is an enigma, which I will investigate by:
1. Establishing Earth's exact climate beat during the early and mid-Coolhouse transitions;
2. Determining which processes caused Earth's climate beat to switch from eccentricity to obliquity;
3. Exploring if future warming could reverse this switch.
CoolRhythms will be hosted at UCL in collaboration with a network of world experts. To achieve my aims, I will combine data science with a novel targeted sampling approach that integrates stratigraphy and geochemistry to optimise information recovery. I will establish Earth's climate beat across the key transitions by filling gaps in our knowledge with new data from deep-sea microfossils and by resolving conflicting interpretations of existing records. I will develop software to characterise the climatic beat in the different records and then combine them to acquire a global view of climate. I will analyse the stable oxygen and carbon isotope and trace element composition of microfossils from deep-sea sediments, collected during IODP ocean drilling expeditions in all ocean basins. I will combine this geochemistry with the sedimentary composition to reconstruct high-resolution ice volume and ocean circulation patterns at the same scale as Earth's climate beat. I will also use modelling to test how the location of the ice growth affects the climate beat and whether an eccentricity driven beat could return in the future.
My approach will enable me to determine which Earth system feedback caused the differing climate beats during these transitions. Refining our understanding of how Earth's climate beat varied during warmer and cooler climate states will ultimately help understand how a warmer Earth may affect the variability of future climate.
| Description | Collaboration with Expedition 378 science party |
| Organisation | International Ocean Discovery Programme (IODP) |
| Country | United States |
| Sector | Charity/Non Profit |
| PI Contribution | This award has led to an international collaborative effort for data collection with other members of the International Ocean Discovery Program (IODP) Expedition 378 Science Party. This collaboration includes improving the stratigraphic section of the expedition material, a joint sampling effort generate a high-resolution benthic foraminiferal stable isotope stratigraphy and an international collaboration to calibrate shared expedition data using specialist multi-proxy analyses. |
| Collaborator Contribution | 1. Improving the stratigraphic composite section of the expedition material: this involves a collaborative effort between researchers in 3 institutes in both Europe (UK and Germany) and the USA. 2. Joint sampling effort to generate a high-resolution benthic foraminiferal stable isotope stratigraphy: in total, we are sharing samples and stable isotope data between 5 laboratories throughout Europe (based in Germany, Norway and the UK) to achieve a high quality record that a single lab could not complete on their own. 3. Expedition data callibration using multi-proxy analyses: we are collaborating as a wider group of 6 laboratories in Europe and the US (based in the UK, Germany and the USA) to calibrate expedition data to understand controls on sediment deposition in the South Pacific Ocean in relation to the onset of Antarctic glaciation. Each laboratory is contributing specialist datasets to integrate together. We received samples from IODP to achieve our portion of these collaborative efforts. Several grants will contribute to parts of this collaboration. |
| Impact | Wilkens, R.H., Drury, A.J., Westerhold, T., Röhl, U., 2022 'Data Report: Depths of U1553 Off-Splice Data Adjusted to the U1553 Splice', Proceedings of the IODP, Vol. 378 Publication (includes Open Access Data): https://doi.org/10.14379/iodp.proc.378.202.2022 Drury, A.J., Westerhold, T., Wilkens, R.H., Röhl, U., 2022 'Data report: splice adjustment for Site U1553', Proceedings of the IODP, Vol. 378 Publication (includes Open Access Data): https://doi.org/10.14379/iodp.proc.378.201.2022 Röhl, U., Thomas, D.J., Childress, L.B., and the Expedition 378 Scientists (including A.J. Drury), 2022. South Pacific Paleogene Climate. Proceedings of the International Ocean Discovery Program, 378: College Station, TX (International Ocean Discovery Program). Publication: https://doi.org/10.14379/iodp.proc.378.2022 Thomas, D.J., Röhl, U., Childress, L.B., and Expedition 378 Scientists (including A.J. Drury), 2020, 'Expedition 378 Preliminary Report: South Pacific Paleogene Climate', Proceedings of the International Ocean Discovery Program, Vol. 378 Publication: https://doi.org/10.14379/iodp.pr.378.2020 |
| Start Year | 2020 |
| Description | ACS International Schools STEAM event |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Schools |
| Results and Impact | The ACS partnership arranged a STEAM event at Thorpe Park, where I attended as part of the UCL GEOBUS team to highlight the field of Earth Sciences. Over 8.5 thousand students and 1000+ teachers and support staff attended. The GeoBus stand was very busy throughout the event. The event was aimed at enhancing the standards of teaching and learning through innovative initiatives. |
| Year(s) Of Engagement Activity | 2022 |
| URL | https://www.steam2022.org |
| Description | Participation in the first phase of the UCL Trellis event. |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | Local |
| Primary Audience | Public/other audiences |
| Results and Impact | This activity is ongoing. Dr Rosemary Willat and myself applied to the UCL Trellis programme, aiming to bring together artists, UCL researchers and east London communities. We proposed a potential collaboration under the theme "How do we sense climate", bringing together Rosemary's expertise in remote sensing and my expertise in palaeoclimatology. We took part in the first phase "Matchmaking" event and we are now preparing a submission to the second phase to request £2,000 to develop ideas for a collaborative commission. The activity is ongoing, so the full engagement potential has not yet been reached. |
| Year(s) Of Engagement Activity | 2023 |
| URL | https://www.ucl.ac.uk/ucl-east/sites/ucl_east/files/trellis_4_-_researcher_call-out_final.pdf |