Periodic Reporting for period 3 - WARMCOASTS (Sea level and extreme waves in the Last Interglacial)
Reporting period: 2021-11-01 to 2023-04-30
The ERC StG "WARMCOASTS" project aims to enhance our understanding of the Last Interglacial period, characterized by a slightly warmer climate than today. During this period, global temperatures were slightly higher, resulting in smaller ice sheets and higher sea levels. The Last Interglacial serves as a "process-analog" for the potential impacts of a warmer future climate, despite being driven by different factors than the current warming trend caused by increased carbon dioxide levels.
While we possess a broad understanding of the Last Interglacial climate, there are still uncertainties and debates surrounding key details. WARMCOASTS focuses on addressing three crucial open questions related to sea level and coastal changes during the Last Interglacial.
Firstly, the prevailing belief is that the sea level during this period was 6-10 meters higher than today. However, recent studies have highlighted significant uncertainties in this estimate, which must be resolved before utilizing Last Interglacial sea levels as a proxy for ice sheet melting in a warmer climate.
Secondly, there is debate about the existence of sea-level oscillations during a stable period within the Last Interglacial. Some studies propose that rapid ice-sheet melting caused these oscillations, while others reject this hypothesis. Understanding the nature and presence of these oscillations is crucial for assessing the sensitivity of ice sheets to small changes in polar temperatures.
Lastly, there is ongoing discussion regarding the occurrence of stronger sea storms/hurricanes in certain coastal regions during the Last Interglacial compared to today. Geological evidence supporting this hypothesis is limited to local contexts in the Bahamas and Bermuda, and further findings related to "stronger storms" are essential for predicting potential coastal damage under future climate conditions.
These three open questions share a common objective: advancing our knowledge of the Last Interglacial to determine the potential impacts on coastal areas as global temperatures continue to rise. WARMCOASTS is addressing these open questions through five Work Packages.
While we possess a broad understanding of the Last Interglacial climate, there are still uncertainties and debates surrounding key details. WARMCOASTS focuses on addressing three crucial open questions related to sea level and coastal changes during the Last Interglacial.
Firstly, the prevailing belief is that the sea level during this period was 6-10 meters higher than today. However, recent studies have highlighted significant uncertainties in this estimate, which must be resolved before utilizing Last Interglacial sea levels as a proxy for ice sheet melting in a warmer climate.
Secondly, there is debate about the existence of sea-level oscillations during a stable period within the Last Interglacial. Some studies propose that rapid ice-sheet melting caused these oscillations, while others reject this hypothesis. Understanding the nature and presence of these oscillations is crucial for assessing the sensitivity of ice sheets to small changes in polar temperatures.
Lastly, there is ongoing discussion regarding the occurrence of stronger sea storms/hurricanes in certain coastal regions during the Last Interglacial compared to today. Geological evidence supporting this hypothesis is limited to local contexts in the Bahamas and Bermuda, and further findings related to "stronger storms" are essential for predicting potential coastal damage under future climate conditions.
These three open questions share a common objective: advancing our knowledge of the Last Interglacial to determine the potential impacts on coastal areas as global temperatures continue to rise. WARMCOASTS is addressing these open questions through five Work Packages.
The WARMCOASTS project comprises five work packages (WPs) that collectively aim to investigate and analyze various aspects of the Last Interglacial period. Each work package focuses on specific goals, including the creation of a global database of Last Interglacial sea-level index points, collection of field data on LIG coastal geological sections, analysis of data alongside dynamic topography and glacial isostatic adjustment models, utilization of stratigraphic forward models, and identification of landforms and deposits indicating wave intensity. So far, the project has achieved significant milestones, resulting in several datasets, publications, and ongoing research activities.
Work Package 1 (WP1) successfully achieved the creation of a global database called WALIS (World Atlas of Last Interglacial Shorelines). The database has been finalized and published in the open-access repository Zenodo, with an accompanying paper published in the journal ESSD. Additionally, a second paper describing the WALIS visualization interface has been submitted for publication. All data, software, and conference presentations related to WP1 are available open access. Version 2.0 of WALIS is planned for release before the project concludes.
Work Package 2 (WP2) focused on collecting new field data on Last Interglacial coastal geological sections across the Western Atlantic. Extensive data collection was completed in Patagonia, covering approximately 1000 km of coastline, and 20 sites were surveyed using high-precision GNSS. A total of 322 samples were dated with Amino Acid Racemization. Data analysis and preparation for publication are underway. Field data collection was also carried out on the East Coast of the USA, specifically in Florida and South Carolina, using the same methods employed in Argentina. Samples from these locations are currently being dated with Optically Stimulated Luminescence (OSL). Previous fieldwork in Madagascar resulted in one published manuscript and one manuscript submitted for review. Additional fieldwork is planned for Brazil in the second part of 2023.
Work Package 3 (WP3) aimed to analyze the data collected in WP1 and WP2 in conjunction with Dynamic Topography (DT) and Glacial Isostatic Adjustment (GIA) models to understand crustal movements affecting Last Interglacial shorelines. DT models for the Pliocene epoch in Argentina were completed, providing valuable insights for studying DT in the Last Interglacial (LIG). Work on a database of Holocene sea-level data in Argentina, Uruguay, and Brazil is ongoing and will aid in refining GIA models for the region. Manuscripts exploring the effects of reef isostasy and the identification of the likely source of meltwater causing high sea levels during the LIG have been submitted for publication.
Work Package 4 (WP4) focused on using stratigraphic forward models to investigate intra-interglacial sea-level oscillations during the LIG. Dionisos FLOW model was tested using the study case of Madagascar, and work is ongoing to utilize this model and other types of models at different locations. Fieldwork areas were extended to the ABC islands (Aruba, Bonaire, and Curacao) in the Southern Caribbean to gather field data for calibrating reef stratigraphic forward models. In parallel, efforts are being made to develop a model that can replicate the formation of tidal notches.
Work Package 5 (WP5) aimed to identify and study landforms and deposits indicating wave intensity during the Last Interglacial. Continued work was carried out on data collected in Cape Verde, and hydrodynamic models are being employed to analyze records from Bahia Laura, Argentina. Additionally, a manuscript exploring potential storm surge changes in the LIG has been published.
Work Package 1 (WP1) successfully achieved the creation of a global database called WALIS (World Atlas of Last Interglacial Shorelines). The database has been finalized and published in the open-access repository Zenodo, with an accompanying paper published in the journal ESSD. Additionally, a second paper describing the WALIS visualization interface has been submitted for publication. All data, software, and conference presentations related to WP1 are available open access. Version 2.0 of WALIS is planned for release before the project concludes.
Work Package 2 (WP2) focused on collecting new field data on Last Interglacial coastal geological sections across the Western Atlantic. Extensive data collection was completed in Patagonia, covering approximately 1000 km of coastline, and 20 sites were surveyed using high-precision GNSS. A total of 322 samples were dated with Amino Acid Racemization. Data analysis and preparation for publication are underway. Field data collection was also carried out on the East Coast of the USA, specifically in Florida and South Carolina, using the same methods employed in Argentina. Samples from these locations are currently being dated with Optically Stimulated Luminescence (OSL). Previous fieldwork in Madagascar resulted in one published manuscript and one manuscript submitted for review. Additional fieldwork is planned for Brazil in the second part of 2023.
Work Package 3 (WP3) aimed to analyze the data collected in WP1 and WP2 in conjunction with Dynamic Topography (DT) and Glacial Isostatic Adjustment (GIA) models to understand crustal movements affecting Last Interglacial shorelines. DT models for the Pliocene epoch in Argentina were completed, providing valuable insights for studying DT in the Last Interglacial (LIG). Work on a database of Holocene sea-level data in Argentina, Uruguay, and Brazil is ongoing and will aid in refining GIA models for the region. Manuscripts exploring the effects of reef isostasy and the identification of the likely source of meltwater causing high sea levels during the LIG have been submitted for publication.
Work Package 4 (WP4) focused on using stratigraphic forward models to investigate intra-interglacial sea-level oscillations during the LIG. Dionisos FLOW model was tested using the study case of Madagascar, and work is ongoing to utilize this model and other types of models at different locations. Fieldwork areas were extended to the ABC islands (Aruba, Bonaire, and Curacao) in the Southern Caribbean to gather field data for calibrating reef stratigraphic forward models. In parallel, efforts are being made to develop a model that can replicate the formation of tidal notches.
Work Package 5 (WP5) aimed to identify and study landforms and deposits indicating wave intensity during the Last Interglacial. Continued work was carried out on data collected in Cape Verde, and hydrodynamic models are being employed to analyze records from Bahia Laura, Argentina. Additionally, a manuscript exploring potential storm surge changes in the LIG has been published.
Overall, the project has made significant progress in achieving its goals across multiple work packages, resulting in valuable datasets, publications, and ongoing research activities. WALIS is arguably the most extensive compilation of Last Interglacial sea-level index points to date. The data insertion interface we built for WALIS has no equals in the paleo sea-level community. Thanks to the support provided by PAGES (the Past Global Changes project), WALIS has been updated to include Holocene sea-level data, following existing Holocene database templates and best practices. The number of sea-level data points included in WALIS has surpassed those included in previous global compilations. Furthermore, WALIS is not static, and it will remain open to both new contributions and corrections of existing records as new data becomes available. The data collected in the context of WP2 encompasses a very wide goegraphic span, and is a solid base to gather new insights on sea-level peak during the LIG, as foreseen in WP3. The models adopted in WP4 and WP5, benchmarked with field data, have the potential to give new insights on sea-level oscillations and wave intensity during the LIG.