Information on terrestrial carbon is required for many purposes:
Understanding the global carbon cycle to: identify sources and sinks and their variation over time; predict how these may change in the future; develop succinct indicators of the status of the global climate system;
Assessment of the actual changes in the global/regional carbon cycle and their impacts (e.g. through the IPCC process);
Reporting to Conventions, and supporting the implementation of the Conventions;
Assistance to national, regional and local management in making more cost-effective decisions and in evaluating their consequences;
Providing information to assess the effectiveness of mitigation and adaptation strategies developed in response to climate change;
Providing information to design better mitigation or adaptation strategies in the future;
Providing information for general public, educational purposes, etc.
Specific information requirements for terrestrial carbon have previously been considered by different groups for a variety of purposes. They include policy oriented programmes (e.g. the UN Framework Convention on Climate Change; IPCC, 1996); international research programmes (e.g. IGBP Terrestrial Carbon Working Group, 1998); global observation programmes (e.g. GTOS, 1997); national programmes (e.g. Appendix III); and others. The workshop objective of synthesis was approached in three steps:
Identification of the main policy and science information needs, as articulated in existing documents;
Preparation of summaries of these needs prior to, and presentations during, the workshop;
Synthesis of these various requirements into a coherent framework through plenary discussion.
The policy instruments reviewed include the Kyoto Protocol (Solomon, Appendix III); the UNFCCC guidelines on national greenhouse inventories (Cihlar and Brown, Appendix III); the Convention to Combat Desertification (Gommes, Appendix III); and the Biodiversity Convention (Gommes, Appendix III).
Science requirements were reviewed from the perspective of atmospheric studies (Raupach, Appendix III; Gerbig et al., Appendix III), ecosystem studies (Potter, Appendix III; Running et al., 1999), and from the national perspective, both policy and research (Raupach, Appendix III; Wickland, Appendix III; Chen and Cihlar, Appendix III).
There are many reasons for interest in terrestrial carbon: policy, scientific, economic, management, sustainable development, public/societal, and others. Workshop presentations have described a range of existing requirements at international or national levels. However, not all of the above requirements provide compelling reasons for the establishment and operation of global, systematic, long-term observations of the carbon cycle and the associated aspects of vegetation and soils. The discussion identified four such compelling reasons, and characterized their spatial and temporal attributes: understanding the global carbon cycle, global change assessment, multilateral environmental agreements, and environmental management. Most of the information needed for environmental management and multi-lateral agreements is also required for a focus on carbon. It is thus more cost effective to implement an observing system that integrates all above needs, with the carbon cycle leading the synthesis.
Description. This requirement has both science and policy aspects. The scientific component is the need to understand the characteristics, processes, and principles governing the global carbon cycle and its evolution, in the past and in the future. The terrestrial carbon is mediated by vegetation and soils, but is intimately linked to the global cycle through land - atmosphere and land - ocean fluxes, and must therefore be encompassed in such an inquiry. From the policy perspective, understanding the carbon cycle becomes the basis for evaluating the current status, the significance of the observed trends, and the implications of these for policy development. Since future projections can only be based on models, understanding of the global carbon cycle is also essential to gaining confidence in such projections.
Information required. Fluxes between the terrestrial ecosystems and the atmosphere; changes in carbon pools (both mass and structure); and the understanding of the controlling factors for both fluxes and pools.
Spatial Extent. Global.
Spatial Resolution: Multiple scales, from local to global. Need to resolve the spatial heterogeneity in driving factors (including ecosystem disturbance, topography, land use, soils, etc.). Scaling strategy (local to global), translation algorithms between scales, and data that support these are a critical issue.
Temporal Extent. In principle, ongoing long-term observations are required to cover cycles of various duration (from seasonal to El Niño, solar cycles, ecosystem succession, and others). In practice, this implies multi-decadal observations that cover at least one carbon residence time (length varies between biomes, ~20 to >50 years). It is also important to include recent land cover and land use history, especially regarding its effects on current and future carbon fluxes.
Temporal Resolution. Different time resolutions are required, depending on the governing processes. Some of the diversity can be covered by models, some by direct observations. Also, the resolution required for present and future is usually higher than for the past.
Description. This encompasses the assessment of climate change and of greenhouse gases in the earth system. Such assessments are periodically conducted by the Intergovernmental Panel on Climate Change for the policy community, and they rely on the results of published studies examining various aspects of the global carbon cycle. These assessments serve as the basis for developing policies at various levels, from national to global.
Information Required. Fluxes between the terrestrial ecosystems and the atmosphere; changes in carbon pools (both mass and structure); and the understanding of the controlling factors for both fluxes and pools.
Spatial Extent. Global.
Spatial Resolution. Multiple scales, from local to global. Need to resolve the spatial heterogeneity in driving factors (including ecosystem disturbance, topography, land use, soils, etc.). Scaling strategy (local to global), translation algorithms between scales, and data that support these are a critical issue.
Temporal Extent. The assessments are carried out periodically, about every 3-5 years. However, they are abased on studies conducted over various time frames, from past to future. Therefore, ongoing long-term observations are required. In practice, this implies ongoing, multi-decadal observations, from past to the future.
Temporal Resolution. Similar as for section a) above.
Description. This requirement has been established by global or international agreements, designed to deal with specific environmental issues. Certain agreements include periodic reports on some aspect of terrestrial carbon.
Information Required. Depends on the Convention (refer to Appendix III for more detail):
UNFCCC: net fluxes of CO2 and other GHGs, resolved into UNFCC reporting categories;
CCD: information on above ground and soil carbon pools (as part of data on soils);
BDC: land cover at medium and high resolution;
Kyoto Protocol: changes in biomass stocks of ‘Kyoto forest’ (details remain to be negotiated);
It should be noted that land use, land use change, and land cover are an important information input to most of the Conventions. Also, while the information needs of some of the Conventions have not yet been fully defined, their objectives indicate that they would benefit from a range of terrestrial carbon information products.
Spatial Extent. Depends on the Convention. In general, only parts of the global landmass are of concern. For existing Conventions, the specific areas are defined by human activities, or by natural processes affected by human activities.
UNFCCC: all land affected by land use/human activities
CCD: semiarid and sub-humid zones
BDC: all land with flora or fauna
Kyoto Protocol: Kyoto forest.
Spatial Resolution. Varies with Convention; the highest resolution is of the order of 100 metres (minimum area 104 m2).
Temporal Extent. Defined by the Convention. Most existing Conventions are recent and do not have a pre-established termination date.
Temporal Resolution. Defined by the Convention (refer to Appendix III), typically one year or longer. Also varies with the type of information.
Information Required. Of two types, strategic and tactical.
Strategic (for planning): Potential primary productivity; water supply; disturbances (fire, insects, etc.); soil carbon.
Tactical (for management and response assessment): stresses causing decrease in primary productivity (water, temperature, nutrients, soil and atmospheric contaminants); fire and other disturbances.
Spatial Extent. Global, but not uniformly distributed (depends on the national/local priorities/concerns)
Spatial Resolution.
Strategic: high to medium, >~101 to 102 m (>~102 to 104 m2).
Tactical: high, >~101 m (>~102 m2).
Temporal Extent. Ongoing, but also depends on management activities and plans at the various spatial levels
Temporal Resolution.
Strategic: Variable (typically seasonal or longer).
Tactical: Multiple resolutions, from minutes (e.g. biomass fires) to months.
