Needs and Opportunities in Deep Carbon Cycle Research

To date, consideration of the global carbon cycle has focused primarily on near-surface (i.e., relatively low-pressure and temperature) phenomena, with the tacit assumption that oceans, atmosphere and shallow surface environments represent an essentially closed system with respect to biologically available carbon. However, recent data and theoretical analyses from a variety of sources suggest that this assumption may be false. Experimental discoveries of facile high-pressure and temperature organic synthesis and complex interactions between organic molecules and minerals, field observations of deep microbial ecosystems and of anomalies in petroleum geochemistry, and theoretical models of lower crust and upper mantle carbon sources and sinks demand a careful reappraisal of the deep carbon cycle.

Such a reappraisal requires the interaction and collaboration of experts from disparate scientific research fields including cosmochemistry, mineral physics, theoretical geochemistry, petroleum geology, organic chemistry, microbial ecology, high-pressure technology, diamond synthesis, geodynamics, evolutionary biology among many others. 

The Carnegie Institution’s Geophysical Laboratory has received a two-year grant from the Sloan Foundation to convene two Deep Carbon Cycle Workshops and to prepare a document entitled “Needs and Opportunities in Deep Carbon Cycle Research.” This document will serve as the basis for a much more ambitious multi-institution, multi-year proposal to Sloan and other granting organizations.  The Sloan Foundation is thus providing seed money to study what they see as a new interdisciplinary research venture. 

The First Workshop on the Deep Carbon Cycle will take place at the Carnegie Institution’s Broad Branch Road campus in Washington DC on May 15-17, 2008. At this meeting we hope to identify major unanswered questions that should inform the schedule of the workshop, such as:

• What is the origin of deep carbon? Does any primordial carbon remain in Earth’s deep interior? What is the distribution and mineralogical context of carbon in Earth’s deep interior, and has this distribution changed significantly over Earth history?
• How, and on what time frames, do processes of burial and subduction sequester surface carbon? How, and by what processes, is deep carbon returned to the surface and what is the net flux of this deep carbon?
• Do lower crust or mantle processes contribute to biologically available carbon; in particular, is there a deep, abiotic source of organic molecules in petroleum?
• Did subsurface process, including hydrothermal organic synthesis and mineral-molecule interactions, play a key role in life’s origins?
• What is the nature and extent of deep microbial life? How do deep microbes affect the global carbon cycle?

The ultimate objective of this project is to elucidate and refine key questions related to the deep carbon cycle and to develop a comprehensive research strategy to tackle promising new directions for experimental, theoretical and field studies to advance our understanding.

[Workshop is by invitation only.]