Hawaiian Drowned Reefs: Climate variability and coral reef response to environmental change in the sub-tropical Pacific over the last 500 ky
Lead Research Organisation:
University of St Andrews
Department Name: Earth and Environmental Sciences
Abstract
This research will produce records of seawater temperature and seawater chemistry in the Sub-tropical Pacific Ocean over the last 500,000 years. This time frame spans the last 5-6 glaciations and these temperature records will allow us to determine how climate changed as the ice sheets first advanced and then subsequently melted. We will correlate temperature records with known drivers of climate change such as increases in atmospheric carbon dioxide and variations in how the planet is tilted towards the sun. The temperature records will also allow us to explore how the severity and frequency of climate events such as El Nino-Southern Oscillation has varied in the past.
In addition to these climate records, the research will also provide information as to how corals have responded to climate change in the past and how this influenced how they built reefs. In the present day, coral reefs support the livelihoods of billions of people. The planned research will determine if reefs grew more slowly or more rapidly in the past compared to the present day and if they were more or less resilient to erosion.
In addition to these climate records, the research will also provide information as to how corals have responded to climate change in the past and how this influenced how they built reefs. In the present day, coral reefs support the livelihoods of billions of people. The planned research will determine if reefs grew more slowly or more rapidly in the past compared to the present day and if they were more or less resilient to erosion.
Publications
Webster J
(2025)
Hawaiian Drowned Reefs
Webster J
(2025)
Hawaiian Drowned Reefs
Webster J
(2025)
Hawaiian Drowned Reefs
Webster J
(2025)
Hawaiian Drowned Reefs
Webster J
(2025)
Hawaiian Drowned Reefs
Webster J
(2025)
Hawaiian Drowned Reefs
Webster J
(2025)
Hawaiian Drowned Reefs
Webster J
(2025)
Hawaiian Drowned Reefs
Webster J
(2025)
Hawaiian Drowned Reefs
Webster J
(2025)
Hawaiian Drowned Reefs
| Description | Shallow marine corals are highly sensitive to sea level and global climate change and preserve a reliable record of past sea level and climate conditions. Knowledge of sea level and global climate variations over the past half a million years is severely limited because of a lack of continuous fossil coral records over this time. To address the critical need for coral records, this project focuses on the submerged fossil reefs around the island of Hawai'i. Frequent and large volcanic eruptions formed and continue to grow the island of Hawai'i, and the island and surrounding shallow coral reefs are pushed down at a rapid and nearly constant rate because of the weight of the volcanic rock erupted onto the land. As the land and coral reefs subside, coral reef growth can match the subsidence rate, and changes in sea level and global climate are preserved in a unique and near continuous fossil coral record covering the last half a million years. Scientific drilling of these reefs will provide a new record of climate and sea level change, including several key time periods where sea level and climate conditions are poorly known. The project has four major scientific objectives: (1) to measure the extent of sea level change over the past half a million years, (2) to investigate why sea level and climate change through time, (3) to investigate how coral reefs respond to abrupt sea level and climate changes, and (4) to improve scientific knowledge of the growth and subsidence of Hawai'i over time. Expedition 389 drilled 35 holes at 16 sites ranging from 131.9 to 1241.8 meters below sea level, recovering 425 meters of core, including very well-preserved mixtures of coralgal and microbialite reef frameworks as well as interlayered and basement volcanic rocks. Preliminary observations and radiometric data confirm that these deposits span the past ~500,000 years, including numerous key periods of major global ice sheet and sea level instability. |
| Exploitation Route | This project will generate unique seasonal records of sea surface temperature, pH and chemistry in the sub-tropical Pacific over the last 5-6 glacial cycles. These high resolution palaeoproxy data are critical for understanding interactions between rapid climate change and sea-level and in testing and validating global climate models for predicting 21st century climate change. In addition, the project will provide valuable information on the response of coral biomineralisation to environmental change. For example, was the response of coral calcification to seawater temperature and pH change different in the past (when change was relatively slow) compared to the present day (when change is rapid)? Do the skeleton material properties suggest that coral reefs in the past were more or less resilient to erosion? This information is critical in predicting the future of coral reefs in a changing climate. |
| Sectors | Environment |
| Description | Expedition member IODP 389: Hawaiian Drowned Reefs |
| Organisation | International Ocean Discovery Programme (IODP) |
| Country | United States |
| Sector | Charity/Non Profit |
| PI Contribution | I am an expedition member for IODP 389: Hawaiian Drowned Reefs. I participated in the onshore science party in February 2024. As part of the team I will work to reconstruct past climate in the Central Pacific and to determine the reef response to this change. |
| Collaborator Contribution | The IODP team is 31 scientists from a range of countries who will work together to reconstruct climate and reef history in Hawaii. |
| Impact | This is a multi-disciplinary partnership. |
| Start Year | 2023 |