A biomarker goldmine in Wilkes Land, Antarctica: nuggets from the Eocene Greenhouse (BIGWIG).

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Summary for General Public: The aim of Integrated Ocean Drilling Programme (IODP) expedition 318, to the Wilkes Land margin of Antarctica, is to decipher the long-term climate and environmental Antarctica: from the pre-glacial Greenhouse world, through the history of multiple growth and collapse of the East Antarctic Ice Sheet (EAIS) and related sea-level changes. The expedition used the specialist drill ship, the Joides Resolution, to recover deep sea sediments. There has been a continuous process of erosion of rocks and soils from the Antarctic continent and deposition of these sediments in the receptive environment of the deep ocean, where layer upon layer of sediment can be laid down in undisturbed succession. These sediments are a repository of information on past environmental and oceanographic changes. Abundant organic molecular fossils (biomarkers) and organic walled microfossils were found in the sediment cores recovered by the IODP 318 expedition. Certain compounds (especially lipids) are quite resistant to decay, so after the producer organisms expire, the biomarkers are preserved in sediments. These biomarkers can be extracted, measured and used to reconstruct changes in parameters such ocean and land temperature over thousands to millions of years; allowing us to quantitatively reconstruct past changes in climate and environments. In expedition IODP 318 these fossils are most abundant is cores dating from the Greenhouse period before ice-sheets were present on Antarctica (the Early Eocene Period, 48 to 55 million years before the present). The presence of the biomarker fossils and organic walled microfossils offers a unique opportunity to study the pre-glacial Antarctic during the critical Early Eocene period, which was characterised by high atmospheric CO2 and mean global temperatures that reached a long-term maximum. Moreover, superimposed on this long-term warmth were a series of relatively rapid (less than a few tens of thousands of years), extreme warm events known as hyperthermals. We will combine state-of-the-art molecular organic biomarker techniques and palynological (organic-walled microfossils) analyses to reconstruct, at high-resolution, changes in land and sea temperatures, atmospheric CO2, carbon cycle changes, terrestrial evaporation/precipitation, marine productivity and salinity. Study of this Greenhouse period and the hyperthermal events is crucial because, since industrialisation, atmospheric concentrations of CO2 have grown to be higher now than at any time in the last 2 million years (Myr). Over the same period, concentrations of other greenhouse gasses (GHGs: methane, nitrous oxides etc) have increased markedly due to human activity. If emissions continue unabated, by 2035 we will have effectively doubled the amount of carbon dioxide in the atmosphere (550 ppm CO2e), compared to the preindustrial period. In other words, atmospherically speaking, we are rapidly heading back towards the Eocene period during which the planet was warmer, planetary ice volumes were much lower and sea-levels much higher than present. We request funding which will allow the PI, James Bendle to co-ordinate project team and lead in the multi-proxy, molecular biomarker analyses. If UK science is to take competitive advantage of the IODP 318 moratorium period (which expires in June 2011), then funding from the April 2010 NERC UK-IODP call is critical to facilitate our proposed analyses and outcomes.