Anna M. Michalak earned her B.S. from the University of Geulph, Ontario and her M.S. and PhD. from Stanford University.

Dr. Michalak on monitoring carbon emissions.

Dr. Michalak introduced her line of research as developing a method for more accurately monitoring global carbon emissions. She began by briefly summarizing the carbon cycle and stated that humans release eight Gig-tons of carbon per year of which four Giga-tons remain in the atmosphere each year.  The total CO₂ released throughout the year is composed by that released by oceans, vegetation and humans.  Dr. Michalak is studying the residue left in the atmosphere after carbon is exchanged between the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere. Her motivation for pursuing  a global carbon monitoring system centers on finding a reliable method of modeling carbon exchange; currently an uncertainty associated with the future of natural carbon sinks and a major source of uncertainty in future climate projections.

Her research is driven by a new US carbon cycle science plan which asks how does the natural process and human actions affect the carbon cycle? How does US policy and management affect the quantity of carbon emissions? And how are ecosystems impacted by increasing greenhouse gasses? With these questions in mind, Dr. Michalak began her study by performing a carbon flux diagnosis, measuring flux net Eddy covariance at data gathering towers throughout the nation.  This data, however, is representative of an area one 1 kilometer squared and represents a measurement of the exchange of carbon, not a measure of the concentrations of CO₂ present.

An inverse model is developed from the data gathered coupled with geological measurement to determine where the source came from. This requires knowledge on wind currents, temperature variances, rainfall etc. The strategy with which she approaches inverse modeling is: understanding the scale-dependence of processes controlling CO₂ flux, spatial-temporal variability, and how this would help reconcile top-down and bottoms-up estimates of CO₂ exchange by minimizing priori assumptions. As an example of the high uncertainly observed from inverse models, Dr. Michalak shared 17 different models all derived from the same data.  From these models it was observed that all provided different estimates of the levels of global carbon exchange.  To obtain a more reliable estimate, a biospheric model and transport model combination was use to achieve inverse modeling of the carbon flux estimates in her research.  Modeling the carbon flux for the US required the need to understand the carbon concentrations that enters from Asia and Mexico.   It is a basic understanding of the spatial distributions of CO₂ at a monthly, seasonal and annual scale. To further understand and validate the inverse model, scale dependence is observed and each variable’s importance identified by incorporating each variable into the equation one at a time and analyzing its impact on the model.

After discussing the results of various scaled inverse models, Dr. Michalak concluded that over the years there has been an unprecedented interest in the global carbon cycle and that a global carbon monitoring system capable of tracking the carbon cycle and anthropogenic emissions must be strong data driven, taking advantage of all available data.  This means that the system must be informative and be driven by process understanding of CO₂ flux, minimizing the reliance on assumptions and not relying on one specific individual, model or inventory.

For further reading consider the following:

• Paper: Whittaker, S., et al., IEA GHG Weyburn CO₂ monitoring & storage project summary report 2000-2004: from the proceedings of the 7th International Conference on Greenhouse Gas Control Technologies, September 5-9, Vancouver, Canada, Volume III, Petroleum Technology Research Center 2004.
• Journal: Janssens, I. A., Freibauer, A., Ciais, P., et al., Europe’s Terrestrial Biosphere Absorbs 7 to 12% of European Anthropogenic CO2 Emissions, Science, 6 June 2003: Pages 1538-1542.
• Journal: Penner, J.E., Eddleman, H., Novakov, T., Towards the development of a global inventory for black carbon emissions, Atmospheric Environment. Part A. General Topics, Volume 27, Issue 8, June 1993, Pages 1277-1295