The story of the evolving chemistry of the oceans, as told in chemical precipitates subsequently preserved as sediments and rocks, is endlessly informative about the past environment of the Earth. As the home of life for close to nine tenths of its entire span on Earth, this history is also a tale of interactions between the biosphere and its surroundings. The interest in this history is restricted neither to the biosphere nor the oceans, however. The atmospheric evolution of a minor – but climatically hugely important – constituent of the atmosphere, carbon dioxide (CO2), is also part of this story. The oceans both control CO2 on short timescales, and carry an imprint of the atmospheric evolution of CO2 in their chemistry. There is also a link between CO2 and another key control on ocean chemistry. The oceans are the ultimate repository of the products of the chemical weathering of the continents - and chemical weathering represents the most important sink for CO2 out of the atmosphere on long timescales. At the other end of the timescale, through fossil fuel CO2 emissions, we ourselves are currently acidifying the oceans at a geologically un-precedented rate, a process that has its own profound consequences for the biosphere. This lecture will focus on what the evolving chemistry of the oceans tells us about the history of the surface of our planet and consider the consequences of human activities for the future.
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Speaker
Derek Vance, University of Bristol
Biography
Derek Vance is a Professor at the University of Bristol. He was an undergraduate at Trinity College Dublin and went on to a PhD at the University of Cambridge. Following a Junior Research Fellowship at Trinity College Cambridge, a NERC Advanced Fellowship at the Open University, and a Marie Curie Fellowship at ETH Zurich, he took up a post as Lecturer at Royal Holloway before moving to Bristol in 2003. Derek’s research has applied the methods of isotope geochemistry to a wide range of Earth Science problems: from mantle degassing, through the dynamics of mountain belts, to its present focus on the evolution of the surface Earth. Over the past decade he has become particularly interested in how the evolving chemistry of the oceans records changes in the past physicochemical environment of the Earth, and how such changes link to the evolution of the biosphere. Most recently he has published on the use of transition metal isotopes in the oceans as signatures for the earliest life on the planet, on tracing the wet episodes in the Sahara that may have facilitated the migration out of Africa of early modern humans, and on the consequences of recent glaciation on Earth for ocean chemistry and the controls on atmospheric carbon dioxide.
