PROGRAM TITLE:	Biogeochemical Exchanges between Terrestrial 
Systems and the Atmosphere and Oceans
ACTIVITY STREAMS:	Process, Observations/Data Mgmt., Modeling
SCIENCE ELEMENT:	Climate/Hydrologic Systems, Biogeochemical 
Dynamics, Solid Earth Processes


DESCRIPTION:  A critical aspect of predicting future atmospheric 
concentrations of natural greenhouse gases relates to understanding the 
sources and sinks of these gases in terrestrial environments.  The USGS 
conducts research on the global carbon and nutrient cycles, past and present, 
to improve understanding of the sources, sinks and exchanges of carbon over 
time under different climatic regimes.  Many of the pathways for carbon (as 
well as nitrogen and phosphorus which are the major nutrients that control 
CO2 uptake) are associated with water fluxes that are a major topic of USGS 
global change research.  Thus, it is logical and efficient to  conduct research on 
the pathways of these gases in conjunction with ongoing USGS studies of the 
hydrologic cycle.  Moreover, other terrestrial events such as volcanic 
eruptions often have significant effects on the global energy balance and, 
thereby, complicate interpretation of natural and anthropogenic contributions 
to global change.  The Bureau of Mines also conducts research on the 
contribution of coal mining to atmospheric methane concentrations.  This 
research has lead to enhanced understanding of methane mitigation and 
mining emissions.
The program emphasizes two primary topics:  (1) Improving the 
understanding of the sources and sinks of carbon dioxide and methane, 
especially in soils, lakes, wetlands, the unsaturated zone, volcano emissions, 
and in areas of active and abandoned coal mining.  The role of terrestrial 
ecosystems in sequestering atmospheric carbon dioxide is a major unknown 
in greenhouse effect predictions.  An effort will be made to develop and 
deploy measurement technology that can help quantify the role of terrestrial 
systems in the carbon budget.  The program also includes development of 
time-dependent models of the global carbon cycle that focus on the feedbacks 
between climate and the rates of exchange of greenhouse gases among the 
various reservoirs, and the subsequent changes in greenhouse gas 
concentrations.  (2) Investigating the flux of carbon, gaseous volatiles and 
aerosols between terrestrial, atmospheric, and marine environments through 
contemporaneous observations (e.g., monitoring volcanic emissions, real-
time monitoring of coal bed methane emissions) and evidence preserved in 
the geologic record.  Emphasis will be given to understanding the links 
between the carbon cycle and those of other elements (e.g., phosphorus, 
nitrogen, and sulfur).
STAKEHOLDERS:  This program is designed to facilitate collaboration with 
researchers involved in long-term ecological and nutrient studies (such as 
being conducted at LTER and Biosphere Reserves) and researching, 
monitoring, and modeling greenhouse gas emissions.  Partnerships and 
agreements are in place between Department of the Interior bureaus and with 
the Department of Energy, U.S. Forest Service, Environmental Protection 
Agency, National Aeronautics and Space Administration, and numerous 
SHORT-TERM POLICY PAYOFFS:  Improved understanding and 
documentation of current terrestrial carbon sources, sinks, and fluxes will 
help balance the modern global carbon budget.  Improved understanding of 
modern processes when combined with information on changes of sources 
and sinks under different climates will improve estimates of future 
atmospheric greenhouse gas concentrations.
				Global Change Research Coordinator
				U.S. Geological Survey
				104 National Center
				Reston, VA  22092
				Phone (703) 648-4450
				Fax   (703)  648-5470