Reading the geological record of natural CO2 variability - Analogue of late 21st century global climate?
12 / 2009 - onbekend
Atmospheric carbon dioxide is predicted to rise to between 500 and 900 parts per million (p.p.m.) by the end of this century; concentrations not seen in perhaps 25 million years. To evaluate climate theories, particularly with regard to feedbacks and climate sensitivity to pCO2, it is considered necessary to study time intervals in the geological past when pCO2 concentrations were high. The aim of the proposed project is to accurately reconstruct atmospheric pCO2 and compare them with global ice volume variations and sea surface temperatures during a series of global climate change events around the Oligocene-Miocene transition (~28-17 Ma). This is probably the interval when the planet for the last time experienced atmospheric pCO2 similar to those expected for the end of the century. Our reconstructions will help to assess the role of the greenhouse gas in the evolution of high-latitude ice sheets. The host institution, the Lamont-Doherty Earth Observatory (at the Columbia University, NY) is a world-leading Geosciences Institution and holds a state of the art geochemistry laboratory with recognized expertise in foraminiferal geochemistry. Key research challenge is the application of a range of foraminifera based proxies (boron isotopes, Mg/Ca, B/Ca) to accurately reconstruct atmospheric pCO2 changes and sea surface temperatures.