Carbon Cycle & Ecosystems
Environmental change and human activities alter Earth's ecosystems and the biogeochemical cycles that are critical to the habitability of our planet. In addition to providing habitat and natural resources while nurturing crucial biodiversity, ecosystems interact with numerous geochemical and physical systems to maintain the global carbon cycle and its control over changes in atmospheric CO2 and CH4 and thus climate. Over the past two centuries, fossil fuel emissions and other human activities increased atmospheric CO2 by 30% and CH4 by 150% to concentrations unprecedented over the past 400,000 years. Understanding these aspects of the Earth system is fundamental to NASA's mission to protect our home planet.
Ecosystems respond continuously to environmental variability and change as well as to numerous disturbances by human activities and natural events. Responses range from changes in ecosystem distribution and extent; impacts on natural resources (e.g., food, fiber, fuel, and pharmaceutical products); ecosystem services (e.g., cleaning of water and air, climate and weather regulation, carbon and nutrient storage and cycling, habitat, maintenance of water resources) to variations in fundamental processes including exchanges of energy, momentum, trace gases, and aerosols with the atmosphere that in turn influence climate.
Our ability to contend with these changes requires observations and fundamental understanding of the responses of ecosystem processes and dynamics to environmental change and to disturbance by human activities and natural events. We must assess the implications of these changes for food production, sustainable resource management, carbon management, conservation of biodiversity, and the maintenance of a healthy environment. In addressing these needs, the Carbon Cycle and Ecosystems Focus Area addresses the following science questions:
- How are global ecosystems changing?
- 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?
Chart: The Carbon Cycle and Ecosystems Roadmap summarizes NASA's strategy for using the global, synoptic perspective of remote sensing to document and understand changes in Earth's carbon cycle, land cover, and ecosystems.
The focus area addresses the distribution and cycling of carbon among the active land, ocean, and atmospheric reservoirs and ecosystems as they are affected by human activity, as they change due to their own intrinsic biogeochemical dynamics, and as they respond to climatic variations and, in turn, affect climate. The goals are to:
- Quantify global productivity, biomass, carbon fluxes, and changes in land cover;
- Document and understand how the global carbon cycle, terrestrial and marine ecosystems, and land cover and use are changing; and
- Provide useful projections of future changes in global carbon cycling and terrestrial and marine ecosystems for use in ecological forecasting and for improving climate change predictions.
Research focuses on providing data and information derived from space-based remote sensing systems to answer focus area science questions. In order to address the heterogeneity of living systems, frequent repeat observations at both moderate and high spatial resolutions are required. Complementary airborne and in situ observations, intensive field campaigns and related process studies, fundamental research, data and information systems, and modeling are all essential for interpreting satellite observations and providing answers to focus area science questions.
The ultimate goal is to project future conditions and trends for ecosystems and the global carbon cycle. This focus area contributes to the improvement of climate projections for 50–100 years into the future by providing key inputs for climate models, including future atmospheric CO2 and CH4 concentrations and representations of key ecosystem and carbon cycle process controls on the climate system. The outbreak and spread of harmful algal blooms, occurrence and spread of invasive exotic species, and the productivity of forest and agricultural systems exemplify ecological forecasts. Resource managers need such forecasts in order to warn the public, target the deployment of resources for mitigation or containment, plant different crops or employ alternative management practices. Policy makers need such forecasts to assess the impacts of various response options and plan for market responses and societal consequences.
Major challenges for the next decade are to document, quantify, and explain decadal-scale variability and trends in both aquatic and terrestrial primary productivity at kilometer spatial resolution, perform repeated high-resolution (~30 m) inventories of land cover and land use change, and report annual balanced global carbon budgets. To meet these challenges, we must characterize and quantify interannual variability, understand key controlling processes, and identify and quantify sources and sinks at sub-regional (~100 km) scales, both on land and within ocean margins. New insight about physiology (e.g., stress effects and efficiency of photosynthetic light use) and the ability to identify groups of species called “functional groups” with similar ecological functions (e.g., nitrogen fixing species, dimethyl-sulfide producers, invasive species) are critical to better understanding of primary productivity and carbon dynamics both on the land and in the ocean.
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 comprise a critical foundation for focus area research. Major advances in knowledge require the new activities delineated on the roadmap diagram. The Large-Scale Biosphere Atmosphere Experiment in Amazonia (LBA) to understand the effects of tropical forest conversion, re-growth, and selective logging on carbon storage, nutrient dynamics, and trace gas fluxes is entering its final synthesis and integration phase. As LBA is completed, emphasis is shifting to North American Carbon Program (NACP) in order to quantify and explain North America’s carbon balance. A new ESSP satellite mission to measure atmospheric CO2 and advance our ability to quantify regional carbon sources and sinks is in the early stages of development.
New measurements of vegetation three-dimensional structure and high resolution atmospheric CO2 profiles will be needed to quantify terrestrial carbon stocks and global sources and sinks, respectively, with sufficient accuracy to balance the global carbon budget and monitor carbon management (both sequestration and emissions reduction) activities. New information on vegetation structure also will enable the characterization of species habitats important for improved ecological forecasts. New measurements of carbon in the coastal ocean and of particle content or profiles throughout the ocean will be needed to reduce uncertainties in coastal carbon fluxes and to quantify carbon export to the deep ocean. In 5–10 years, an intensive Southern Ocean carbon program will be needed to resolve uncertainties in the size, dynamics, and global significance of the Southern Ocean as a carbon sink as well as the processes controlling this sink. In addition, new types of measurements will be needed to characterize plant physiological processes and identify plant functional groups in order to improve process characterizations in ecological models; the candidate measurement technologies (e.g., hyper-spectral, multi-spectral lidar) and analysis approaches will require study and development.
Throughout the next decade, research will be needed to advance our understanding of and ability to model human-ecosystem-climate interactions so that an integrated understanding of Earth system function can be applied to our goals. Changes in social, economic, and cultural systems are combining with global environmental changes as forcings of change in a world that is more populated, urban, and interconnected than ever before. Innovative research to blend social and natural science information and to advance model coupling, model-data fusion, and data assimilation approaches will be needed.
NASA research in the Carbon Cycle and Ecosystems Focus Area will employ the global, synoptic perspective of space and unique NASA scientific and management expertise to reduce uncertainties and provide quantitative information concerning atmospheric concentrations of greenhouse gases, changes in terrestrial ecosystem and oceanic carbon sinks, trends in primary productivity, species extinction and invasion, land cover and land use change, and the health and sustainability of global ecosystems. Continuing NASA research will focus on tracking, comprehending, and predicting these changes and their impacts on society and the Earth system. Specifically this program of research will produce:
- Assessments of ecosystem response to climatic and other environmental changes and the effects on food, fiber, biodiversity, primary productivity, and other ecological goods and services;
- Quantitative carbon budgets for key ecosystems along with the identification of sources and sinks of carbon dioxide and other greenhouse gases;
- Documentation and prediction of land cover and land use change as well as assessments of consequences to society and for resource sustainability;
- Understanding of ecosystem interactions with the atmosphere and hydrosphere leading to comprehensive modeling of the exchange of gases, aerosols, water, and energy among the components of the Earth system;
- Better representations of ecosystem processes within global climate models leading to more credible climate predictions.
The resulting information and scientific understanding will enable sound resource management strategies and policy decisions pertaining to carbon, agriculture, forestry, fisheries, and other natural resources.