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This report identifies a set of systematic, long-term terrestrial and atmospheric observations needed to implement an effective terrestrial carbon observation programme, highlights a number of challenges that need to be addressed, and outlines an approach to implementing an initial observing system. ‘Terrestrial carbon’ refers to carbon contained in terrestrial vegetation or soil stocks and the fluxes from or to the atmosphere and oceans through which it participates in the global carbon cycle. The 1999 IGOS-P meeting also endorsed the preparation of an overarching global carbon cycle theme which has since been initiated through the Integrated Global Carbon Observation (IGCO) theme and which provides the framework for integrating the terrestrial, atmospheric and oceanic components. In the IGCO context, this report deals with the terrestrial and atmospheric components of the global carbon cycle.

Information on the terrestrial carbon distribution and changes is required by several policy and research areas. Key among these are (i) national commitments to environmental conventions and multilateral agreements that require terrestrial carbon information; (ii) acceptance by the Conference of Parties of the need for systematic observations and reporting within the UN Framework Convention for Climate Change, including the Kyoto Protocol; (iii) the need for information on the productivity and changes of terrestrial biosphere which, together with land use and other information form a basis for sustainable development and resource management, and (iv) improved knowledge of the carbon cycle, to allow more effective policy development to deal with climate variability, change, impact and adaptation. Accordingly, users of terrestrial carbon information range from national ministries (for policy setting, reporting, sustainable development planning) to international scientific and policy bodies.

Although various important building blocks for systematic global carbon observation already exist, there are gaps and deficiencies as well as a lack of coordination and continuity. Therefore, a focused and dedicated effort is needed to implement an initial observing system. The following goals are proposed for the initial system, with a timetable partly conditioned by the schedule of the Kyoto Protocol:

1. By 2005, demonstrate the capability to estimate annual net land-atmosphere fluxes at a subcontinental scale (107 km2) with an accuracy of +/- 30% globally, and a regional scale (106 km2) over areas selected for specific campaigns with a similar or better accuracy;

2. By 2008, improve the performance to better spatial resolution (106 km2 globally) and an increased accuracy (+/- 20%);

3. In each case, produce flux emission estimate maps with the highest spatial resolution enabled by the available satellite-derived and other input products.

To achieve these goals, IGOS-P needs to ensure the acquisition of surface and satellite observations for a range of products, the preparation of these products, and their use in models of carbon exchange with the atmosphere to yield estimates of sources and sinks of terrestrial carbon on an annual basis. An important associated objective is a research and development programme that will lead to continuing improvements in the comprehensiveness and quality of the observation methods, products and model outputs.

The economic and social significance of many aspects of the carbon cycle have led to numerous terrestrial and atmospheric observation initiatives undertaken or planned. Thus the primary roles for IGOS-P in establishing a long-term terrestrial carbon observation programme are to ensure that gaps in the observing systems are filled; to achieve continuity, consistency and ongoing improvements in the observing capabilities; and to facilitate coordination and collaboration among the contributors so that the products have the expected utility and impact. Regarding observation capabilities, this report identifies issues that need to be addressed in two major challenges, long term continuity and consistency of observations (25 issues) and knowledge development (28 issues).

Regarding the long-term continuity and consistency challenge, the major issues may be summarized as follows:


a Land cover and change, seasonal growth cycle, fires:

1. Continuity of calibrated, fine resolution satellite optical measurements from both fixed-view and pointable sensors, as well as Synthetic Aperture Radar (SAR) data. This data should be accompanied by a consensus strategy for global satellite data acquisition at fine resolution.

b Biomass:

2. Ongoing availability of, and improvements in, canopy structure measurements from satellite sensors, beyond the planned Vegetation Canopy Lidar/Earth System Science Pathfinder mission.

c Product generation:

3. Institutional arrangements for product generation and quality control, including incorporation of in situ observations as appropriate, intercalibration between missions, and reprocessing of archived data.


a Ecological and soil observations:

4. Increased density of in situ observations and more effective access to and use of data available within countries, in combination with satellite-derived products.

b Surface-atmosphere fluxes:

5. Maintaining the existing flux measurement programmes for at least ten years at a site. Expanding the current network in underrepresented geographic regions and ecosystem conditions, and improving international coordination of data handling and use. In addition, continuously operate selected long-term stations to serve as anchor sites for understanding climate variability.

6. Ensuring that the expanded in situ networks provide data to improve the quality of satellite-derived products and the performance of biogeochemical models.

c Atmospheric concentration measurements:

7. Ensuring the long-term continuity and stability of the global air flask sampling programmes, including support for improved accuracy and inter-laboratory calibration.

8. Adding sites to the existing air flask sampling network to improve results of atmospheric inversions for the terrestrial ecosystems.

9. Ensuring increases in the resolution and coverage of fossil fuel emission data provided by national agencies.

The 28 knowledge development issues concern the new observing, analysis and modeling tools that are essential to improve the quality or comprehensiveness of the acquired terrestrial carbon information. Progress in these areas should be regarded as an integral and necessary part of the systematic, long-term observation scheme.

It is recommended that IGOS Partners:

1. Request that the IGCO Theme Team use this report in preparing the IGCO theme report.

2. request the Strategic Implementation Team (SIT) to review and confirm the commitments to existing and planned missions and programmes (Appendix 3.).

3. examine the specific continuity and knowledge challenge issues identified in this report and where feasible, allocate responsibility for addressing the gaps.

4. take the following initial steps toward TCO implementation, within the IGCO framework:

a) identify lead IGOS Partner(s) responsible for TCO implementation;

b) charge the lead Partner to prepare draft terms of reference in consultation with the Partners and to establish a TCO Implementation Team as outlined in section 6.2;

c) request TCO Implementation Team (IT) to submit a draft work plan with required IGOS-P contributions (beyond those in recommendations 2 and 3 above) within 4 months of the IT establishment;

d) agree to support the work of TCO IT by making available staff and financial resources for its activities; and commit to responding to the TCO IT work plan within three months following its delivery.

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