The NASA Earth Science Research and Analyses Program is comprised of six interdisciplinary science focus areas. Carbon Cycle and Ecosystems is one of them. For more information about NASA’s Earth Science Research Program, see the 2007 NASA Science Plan.

Earth's carbon cycle and ecosystems both influence and respond to global environmental changes. Major uncertainties in climate science stem from uncertainties in the global carbon cycle. Two garner special attention in NASA's program. First, at present the difference between the total release of carbon dioxide (CO₂) to the atmosphere from known sources and the total amount of (CO₂) removed from the atmosphere by known carbon sinks does not equal the change in (CO₂) concentration of the atmosphere. Approximately one quarter of this carbon (about 1.9 Petagrams per year) is unaccounted for, but there is accumulating evidence that this "missing sink" is in Northern Hemisphere terrestrial systems. Second, how terrestrial and marine ecosystems may respond to changes in climate in combination with other contemporary environmental changes, such as changes in land use and management, invasions of exotic species, nitrogen deposition, and acidification of the surface ocean, is unclear. What is clear is that these environmental changes are occurring on an unprecedented scale, in both rate and geographical extent. Resolution of these uncertainties is needed because of the profound implications for future climate, food production, biodiversity, sustainable resource management, and the maintenance of a healthy, productive environment.

Thus, three objectives are identified for Carbon Cycle and Ecosystems research:

1. document and understand how the global carbon cycle, terrestrial and marine ecosystems, and land cover and use are changing;
2. quantify global productivity, biomass, carbon fluxes, and changes in land cover; and
3. provide useful projections of future changes in global carbon cycling and terrestrial and marine ecosystems for use in ecological forecasting and as inputs for improved climate change predictions.

In the current decade, key missions now in development address these objectives. Well-calibrated and validated systematic observations of moderate-resolution ocean color, vegetation biophysical properties, fire, and land cover as well as high-resolution land cover form a critical foundation for focus area research. The Suomi NPOESS Preparatory Project (NPP) and Landsat Data Continuity Mission (LDCM) are intended to provide near-term continuity as these observations transition into the U.S. operational remote-sensing domain. The focus area depends on the continued availability of these climate-quality systematic observations and informs NASA investment in the development of advanced technologies to improve these observations and make them more economical in the future. The OCO will measure atmospheric carbon dioxide concentrations and advance our ability to locate and quantify regional carbon sources and sinks by dramatically increasing the number of global measurements over what can be provided with ground-based networks and aircraft.

Priority new observations are:

1. measurements of vegetation height and profiles of three-dimensional ecosystem structure to estimate above-ground biomass and carbon stocks with greatly reduced uncertainties and to characterize species habitats in ways that will enable exploration of fundamental controls on biodiversity;
2. well-calibrated measurements of the coastal ocean that allow discrimination and quantification of dissolved and particulate organic matter, phytoplankton pigments, and sediments in order to deduce the fate of carbon in the coastal ocean and quantify its role as either a source of sink for carbon; and
3. measurements of the distribution, abundance, and variability of plant groups with important ecological and physiological functions (e.g., nitrogen-fixing species, invasive species, plants with differing photosynthetic pathways or growth rates) to be used to improve process characterizations in predictive models and develop more refined land-cover analyses.

In addition, following the completion of a successful OCO mission, advanced, high-resolution measurements of atmospheric profiles of carbon dioxide and methane will be needed to further refine our ability to quantify global sources and sinks, providing accuracy sufficient to balance the global carbon budget and monitor carbon-management activities.

Carbon Cycle and Ecosystems Science Questions

• How are global ecosystems changing?
• What trends in atmospheric constituents and solar radiation are driving global climate change?**
• What changes are occurring in global land cover and land use, and what are their causes?
• How do ecosystems, land cover and biogeochemical cycles respond to and affect global environmental change?
• What are the consequences of land cover and land use change for human societies and the sustainability of ecosystems?
• What are the consequences of climate change and increased human activities for coastal regions?**
• How will carbon cycle dynamics and terrestrial and marine ecosystems change in the future?

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NASA Official: Jim Collatz 
Curator: Carla Evans