Periodic Reporting for period 5 - WARMCOASTS (Sea level and extreme waves in the Last Interglacial)
Periodo di rendicontazione: 2024-11-01 al 2025-09-30
The WARMCOASTS project focused on the Last Interglacial (LIG), a warm period that lasted from 128 to 116 thousand years ago, characterised by a climate warmer than the pre-industrial. In the LIG, ice sheets were smaller, and sea levels were higher than today. As the LIG is often considered as a process-analog for a future warmer climate, a better understanding of this period is crucial.
The project addressed three key knowledge gaps about the sea-level rise and coastal processes during the LIG:
1. Uncertainty surrounding LIG peak global mean sea level (GMSL)
2. Presence and magnitude of rapid oscillations causing abrupt sea level rises during the LIG.
3. Testing and benchmarking of the highly controversial hypothesis that the LIG was characterized by waves more intense than those observed today.
Filling or better framing these knowledge gaps is key to test and improve climate models, which are in turn used to produce future climate scenarios. In this framework, a better understanding of LIG sea level peaks, rapid ice sheet collapse, and extreme sea storm events will help inform our society's understanding and preparedness to our future warmer climate.
The project addressed three key knowledge gaps about the sea-level rise and coastal processes during the LIG:
1. Uncertainty surrounding LIG peak global mean sea level (GMSL)
2. Presence and magnitude of rapid oscillations causing abrupt sea level rises during the LIG.
3. Testing and benchmarking of the highly controversial hypothesis that the LIG was characterized by waves more intense than those observed today.
Filling or better framing these knowledge gaps is key to test and improve climate models, which are in turn used to produce future climate scenarios. In this framework, a better understanding of LIG sea level peaks, rapid ice sheet collapse, and extreme sea storm events will help inform our society's understanding and preparedness to our future warmer climate.
The WARMCOASTS project worked towards advancing the understanding of coastal and sea-level dynamics during the Last Interglacial (LIG) through an integrated programme of fieldwork, data compilation, and modelling across five Work Packages. The project achieved its overarching goals through three key objectives.
Objective 1 aimed to better constrain peak global mean sea level during the LIG. This was achieved through WP1, WP2 and WP3. In WP1, the main result was the creation of the World Atlas of Last Interglacial Shorelines (WALIS) — a standardized global database that was developed via a coordinated international collaboration. WALIS now serves as an open-access global reference for LIG palaeo–sea-level research. In WP2 and WP3 geological surveys were carried out in several study areas. In combination with geophysical modelling, this body of work revealed that peak sea level likely remained below 5 m, significantly lower than previously estimated. In WP3, novel work on dynamic topography, sediment isostasy, and the newly formulated concept of reef isostasy was carried out, further advancing our knowledge on LIG sea-level changes.
Objective 2 explored short-term sea-level oscillations within the LIG. IN WP4, different kinds of stratigraphic forward models (Dionisos Flow and REEF) were used to simulate reef growth under variable sea-level histories, comparing modelled with observed reefs. This work demonstrated that these models can reproduce observed reef systems, and showed that multi-stepped or backstepped reef morphologies could arise from either rapid oscillations, or reef dynamics alone. Complementary modelling of tidal notches and field data from the Caribbean, Indian Ocean, and Mediterranean provided new insights into the tempo of sea-level change, showing that intra-interglacial fluctuations may have occurred more rapidly than previously recognised.
Objective 3 focused on locating and quantifying proxies of extreme waves. This objective was pursued mainly in WP5, using innovative approaches integrating field geology, hydrodynamic and climate modelling, and remote sensing. Field campaigns in Argentina and Cape Verde showed the potential of beach and boulder ridges to investigate paleo wave processes at local scale. A pioneering study also modelled sea-level extremes globally under LIG and pre-industrial climates, showing that warmer orbital conditions amplified storm surges and coastal flooding potential.
Across all WPs, the project introduced novel interdisciplinary and open-science practices, including freely available databases, code repositories, and visualization tools hosted on Zenodo, GitHub, and FigShare. Knowledge transfer was reinforced through the training of early-career scientists, one Ph.D. completion, and multiple master’s theses.
Dissemination and exploitation of the results were extensive: WALIS and related datasets have collectively exceeded 80,000 views and downloads; over 30 peer-reviewed papers were published or submitted; and outreach activities through media and social platforms expanded the visibility of ERC-funded science. Together, these outcomes establish a durable scientific and infrastructural legacy that continues to shape global research on sea-level change and coastal dynamics.
Objective 1 aimed to better constrain peak global mean sea level during the LIG. This was achieved through WP1, WP2 and WP3. In WP1, the main result was the creation of the World Atlas of Last Interglacial Shorelines (WALIS) — a standardized global database that was developed via a coordinated international collaboration. WALIS now serves as an open-access global reference for LIG palaeo–sea-level research. In WP2 and WP3 geological surveys were carried out in several study areas. In combination with geophysical modelling, this body of work revealed that peak sea level likely remained below 5 m, significantly lower than previously estimated. In WP3, novel work on dynamic topography, sediment isostasy, and the newly formulated concept of reef isostasy was carried out, further advancing our knowledge on LIG sea-level changes.
Objective 2 explored short-term sea-level oscillations within the LIG. IN WP4, different kinds of stratigraphic forward models (Dionisos Flow and REEF) were used to simulate reef growth under variable sea-level histories, comparing modelled with observed reefs. This work demonstrated that these models can reproduce observed reef systems, and showed that multi-stepped or backstepped reef morphologies could arise from either rapid oscillations, or reef dynamics alone. Complementary modelling of tidal notches and field data from the Caribbean, Indian Ocean, and Mediterranean provided new insights into the tempo of sea-level change, showing that intra-interglacial fluctuations may have occurred more rapidly than previously recognised.
Objective 3 focused on locating and quantifying proxies of extreme waves. This objective was pursued mainly in WP5, using innovative approaches integrating field geology, hydrodynamic and climate modelling, and remote sensing. Field campaigns in Argentina and Cape Verde showed the potential of beach and boulder ridges to investigate paleo wave processes at local scale. A pioneering study also modelled sea-level extremes globally under LIG and pre-industrial climates, showing that warmer orbital conditions amplified storm surges and coastal flooding potential.
Across all WPs, the project introduced novel interdisciplinary and open-science practices, including freely available databases, code repositories, and visualization tools hosted on Zenodo, GitHub, and FigShare. Knowledge transfer was reinforced through the training of early-career scientists, one Ph.D. completion, and multiple master’s theses.
Dissemination and exploitation of the results were extensive: WALIS and related datasets have collectively exceeded 80,000 views and downloads; over 30 peer-reviewed papers were published or submitted; and outreach activities through media and social platforms expanded the visibility of ERC-funded science. Together, these outcomes establish a durable scientific and infrastructural legacy that continues to shape global research on sea-level change and coastal dynamics.
WARMCOASTS advanced the frontiers of sea-level and coastal research by combining global data synthesis, refined geophysical modelling, and innovative field and numerical approaches. Its most transformative outcome is the World Atlas of Last Interglacial Shorelines (WALIS) — the first standardized, open-access database of Last Interglacial sea-level indicators. Published as a Special Issue in Earth System Science Data, WALIS compiles over 4,500 sea-level proxies, information on 4000 dated samples, and provides user-friendly interfaces for data entry and visualization. This infrastructure has become a global reference for transparent and reproducible palaeo–sea-level research.
A major conceptual advance arose from integrating geological evidence with dynamic topography (DT) and glacial isostatic adjustment (GIA) models, leading to a re-evaluation of Last Interglacial sea levels. Contrary to previous highstand estimates exceeding 6–9 m, results published in PNAS indicate a global mean sea level of about 1.2 m above present, with a low probability of surpassing 5 m, a paradigm shift that refines both palaeo reconstructions and future projections. These results are confirmed by local studies realised within WARMCOASTS.
WARMCOASTS also introduced new modelling and conceptual frameworks, including the novel theory of reef isostasy, which describes the feedback between reef growth and local sea-level change, improved sediment isostatic adjustment models, and a morphological model capable of reproducing observed tidal notch morphologies under fluctuating sea-level regimes.
In the study of coastal extremes, the project pioneered integrated geological–hydrodynamic approaches, showing that Last Interglacial storms in Cape Verde reached magnitudes comparable to modern hurricanes. Climate–hydrodynamic modelling further revealed that warmer orbital conditions amplified storm surges and coastal flooding potential.
By uniting geological, geophysical, and modelling disciplines under a fully open-science framework, WARMCOASTS established new methodological and conceptual standards for palaeo–sea-level research. Its open databases, reproducible modelling tools, and interdisciplinary collaborations ensure a lasting scientific legacy that will guide future studies on sea-level change, coastal evolution, and climate-driven extremes .
A major conceptual advance arose from integrating geological evidence with dynamic topography (DT) and glacial isostatic adjustment (GIA) models, leading to a re-evaluation of Last Interglacial sea levels. Contrary to previous highstand estimates exceeding 6–9 m, results published in PNAS indicate a global mean sea level of about 1.2 m above present, with a low probability of surpassing 5 m, a paradigm shift that refines both palaeo reconstructions and future projections. These results are confirmed by local studies realised within WARMCOASTS.
WARMCOASTS also introduced new modelling and conceptual frameworks, including the novel theory of reef isostasy, which describes the feedback between reef growth and local sea-level change, improved sediment isostatic adjustment models, and a morphological model capable of reproducing observed tidal notch morphologies under fluctuating sea-level regimes.
In the study of coastal extremes, the project pioneered integrated geological–hydrodynamic approaches, showing that Last Interglacial storms in Cape Verde reached magnitudes comparable to modern hurricanes. Climate–hydrodynamic modelling further revealed that warmer orbital conditions amplified storm surges and coastal flooding potential.
By uniting geological, geophysical, and modelling disciplines under a fully open-science framework, WARMCOASTS established new methodological and conceptual standards for palaeo–sea-level research. Its open databases, reproducible modelling tools, and interdisciplinary collaborations ensure a lasting scientific legacy that will guide future studies on sea-level change, coastal evolution, and climate-driven extremes .