Unlocking the climate secrets of a national icon

Expedition Co-Chief Scientists

Dr Jody WebsterJody Webster is a Senior Lecturer in the School of Geosciences, the University of Sydney, Australia. He is an expert on carbonate sedimentology and stratigraphy and interpretation of marine geology and geophysical data. Jody graduated from the University of Sydney in 2000 and spent several years in the US carrying out his post-doctoral research on fossil coral reefs and carbonate platforms. His research has focused on understanding coral-reef and carbonate-platform evolution and their implications for addressing fundamental problems in climate change and tectonics. In 2007, Jody was chief scientist on the RV Southern Surveyor expedition to gather site survey data for the GBREC Expedition. Jody’s interests also involve linking observational and numerical modeling data to accurately show how reef and carbonate platform evolution in the Indo-Pacific are controlled by changes in sea level, subsidence and growth rates.

Dr Yusuke YokoyamaYusuke Yokoyama is an Associate Professor at the Ocean Research Institute, University of Tokyo, Japan. Yusuke was awarded his PhD at the Australian National University and has previously worked in the USA. His research interest is mainly Quaternary climate change using geochemistry and geophysical measurements and especially changes in sea level during the last 150, 000 years. Yusuke’s work has taken him from the equatorial ocean to Antarctica where he has studied sediment cores, corals, tree-rings and ice cores. He has previously worked on dating fossil corals from the Great Barrier Reef and modelling the history of the area since the last ice age.

Expedition OperatorMission-specific platform operations are conducted for IODP by the European Consortium for Ocean Research Drilling (ECORD), which represents the ocean-drilling efforts of most of Western Europe as well as Canada. Operations are undertaken by the ECORD Science Operator comprising the British Geological Survey (BGS), the University of Bremen and the European Petrophysics Consortium (EPC).

During the expedition regular updates will be posted on the expedition logbook, which can be found on the ECORD Science Operator’s web pages at:

www.eso.ecord.org/expeditions/325/325.php

Integrated Ocean Drilling Program www.iodp.orgThe Integrated Ocean Drilling Program (IODP) is an international marine research program dedicated to advancing scientific understanding of the Earth by monitoring and sampling sub-seafloor environments. Through multiple platforms - a feature unique to IODP - the world’s pre-eminent scientists explore the deep biosphere, environmental changes and solid earth cycles.

24 countries support IODP. Primary funding is provided by the United States National Science Foundation (NSF) and Japan’s Ministry of Culture, Education, Sports, Science and Technology (MEXT). Additional funding is provided through the ECORD contributing members, the People’s Republic of China Ministry of Science and Technology (MOST), the Korea Institute of Geoscience and Mineral Resources (KIGAM), the Australia - New Zealand IODP Consortium (ANZIC) and India’s Ministry of Earth Sciences (MoES).

This brochure was produced and distributed by the ECORD Science Operator.

AcknowledgementsThe map inside of the brochure is provided courtesy of Dr Robin Beaman, James Cook University, Australia. The images of the seabed are from Abbey and Webster (in press).

IODP Expedition 325

www.iodp.orgwww.eso.ecord.org

The Great Barrier Reef Environmental Changes Expedition

Coral reefs and climate change

The deglaciation that followed the last major ice age started some 20, 000 years ago. Knowing the timing and nature of the subsequent sea-level rise is one of the essential components that help us to understand the dynamics of large ice sheets and how the Earth has adjusted since the ice melted. The disappearance of glacial ice sheets was also responsible for dramatic changes in the input of freshwater to the oceans, which disturbed the oceans’ (thermohaline) circulation that in turn impacts on global climate.

The IODP Great Barrier Reef Environmental Changes (GBREC) Expedition will address these issues by collecting cores from fossil coral reefs that grew some 20, 000 to 10, 000 years ago. Coral reefs are excellent sea-level indicators, and their accurate dating is critical for constraining the detailed timing, rate and amplitude of deglaciation events and consequently our understanding of the mechanisms that drive sea-level and climate cycles between glacial and interglacial periods.

‘To construct global sea-level models we need records of change from as many locations as possible. The importance of the Great Barrier Reef is that it’s an area of the Australian shelf that has been essentially stable over the last 20, 000 years, so it’s an ideal place to look at reefs that have developed at different sea levels and climates throughout this period.’ Dr Jody Webster Submerged reef structures on the shelf edge near Noggin Pass, Great Barrier Reef.

Features include parallel barrier reefs comprised of a raised ridge and pinnacles, a lagoon containing patch reefs, and seaward terraces.

The expedition objectives

The main objectives of IODP Expedition 325 are to recover fossil corals and other reef-building material from the shelf edge of the Great Barrier Reef. Detailed study of the cores will allow the scientific team to understand more about a crucial 10, 000 year period in the Earth’s history. The recovery of corals that grew throughout the deglaciation will allow them to reconstruct climate variations based on information such as ocean temperature, salinity and chemistry. The suite of cores will also be studied to see how the reef ecosystem responded to the rapid rise of sea level and changes in climate. This last objective is especially important to our understanding of how the modern Great Barrier Reef (a World Heritage Site) will respond to future changes.

‘There are considerable uncertainties as to how the Great Barrier Reef will respond to changes in our oceans, such as acidification, increasing sea-level rise and sea-surface temperatures in the next 20–30 years. Scientific drilling will provide important insights into how robust the reef is over different timescales and under different environmental conditions.' Dr Yusuke Yokoyama

The GBREC Expedition team, including scientists from 9 countries, plans to recover shallow sediment cores from several key sites in 3 regions (see map top left) using an IODP mission-specific platform operated by the European Consortium for Ocean Research Drilling (ECORD). The drilling targets include the successive reef terraces, relict reefs and the slope, from water depths of about 40 to 200 m.

CooktownRibbon Reef

Noggin Pass

Hydrographer's Passage

Cairns

Townsville

Port Douglas

Km0 10050