Scientists share multidisciplinary discoveries at 'Earth System ...( n_182.htm . Poster Session 30 Abstract...)

Can you imagine our world being devoid of oxygen for almost half of its history? And suddenly there's an abrupt rise at ~2 ga? This amazing picture of our Earth is finding increasing support from rock record geologic data.

"But what intrigues physical and biological scientists alike is why the rise and why at ~2 ga?" remarked Janet Siefert, co-chair for this session. Siefert is a molecular evolutionist at Rice University in Houston, Texas.

"We know with increasing certainty from geologic biomarkers, fossils, and molecular phylogenies that the organisms most likely responsible for this rise, the ubiquitous cyanobacteria or their ancestors, were surely present at least half a million years prior to the rise. So why the lag?"

The rise of oxygen is a great science question. It is unique because there are as many theories that postulate the event as dominated by physical processes as there are ones that predict it was a biologically mediated phenomenon. This session will bring oceanographers, genome analysts, and geoscientists with their competing theories, together in one venue with the hopes that a more substantive and accurate picture of what may have actually occurred can be brought to the fore.

The newest discoveries are coming from papers that are multidisciplinary in nature:

• David Catling, from the Space Science Division of the NASA Ames Research Center and the SETI Institute, will build on the idea that the Archean atmosphere was dominated by methane as the primary greenhouse gas, but expands it to include an explanation for the oxidation of Earth. He postulates that the kinetic effects of oxygen and methane are reversed from today; in effect hydrogen escape to space was inescapable and oxygenation of the atmosphere was irreversible.
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