Surrounding the island of Hawai’i are a series of twelve fossil coral reefs that formed as the reef communities successively grew and were drowned by rising sea-levels and / or the near constant subsidence of the crust around the ever-growing volcanic archipelago of Hawai’i. When combined with Hawai’i’s location away from the influence of any of the large Quaternary ice-sheets, or strong boundary ocean currents that can mask the sea-level and paleoclimate signals, this location represents a unique succession of expended reef sequences, key for the recovery of high-resolution climate and reef response records.
Covering important time periods in the Earth’s climate history, the information contained in these natural fossil reef archives will help scientists reconstruct sea-level change at a much higher resolution than previously possible at a stable far-field site. It will also enable them to investigate the links between global sea-level change and global climate change, and therefore the mechanisms that control abrupt climate change.
These records of natural climate change on a range of scales, from seasonal and decadal signals to the much longer term millennial scale changes, will also provide a framework for evaluating the effects of climate change originating from human activity.
The scientific team will core in up to eleven locations, to a depth of 150 m below the seafloor, with the aim to address questions on four main themes:
- To reconstruct sea-level change in the central Pacific over the last 500,000 years.
- To reconstruct the variability in climate over the last 500,000 years, as recorded in the fossil corals, and better understand the differences in response between a seasonal – inter-annual variation in climate against what represents a more permanent shift in sea surface temperature, rainfall and storm tracks.
- To understand how coral reef systems respond both geologically and biologically to rapid changes in sea-level and climate – for example can reefs turn on and off when they reach certain limits, and how do they recover from disturbances in the system.
- To explain the subsidence and volcanic history of Hawai’i.
