The Integrated Global Observing Strategy Partnership (IGOS-P) is using specific policy-relevant themes as an approach to implementing systematic global observations. In November 1999 IGOS-P requested GTOS with FAO support to lead the Terrestrial Carbon Cycle theme. In response to the request, the Terrestrial Carbon Theme Team was established to prepare this report. The report identifies a set of systematic, long-term terrestrial and atmospheric observations needed to implement an effective terrestrial carbon observation program, 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) the need for improved knowledge of the carbon cycle, dictated by the desire to develop the most effective policies 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 co-ordination 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 sub-continental 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 program that will lead to continuing improvements in the comprehensiveness and quality of the observation methods, products and model outputs.
Because of the economic and social significance of many aspects of the carbon cycle, numerous terrestrial and atmospheric observation initiatives are underway or planned. Thus the primary roles for IGOS-P in establishing a long-term terrestrial carbon observation program 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 co-ordination 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 summarised as follows:
I SATELLITE OBSERVATIONS
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 of SAR data; they 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 VCL/ESSP mission.
c Product generation:
3 Institutional arrangements for product generation and quality control, including incorporation of in situ observations as appropriate, inter-calibration between missions, and reprocessing of archived data.
II IN SITU OBSERVATIONS
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 programs for at least 10 years at a site, expanding the current network in underrepresented geographic regions and ecosystem conditions, and improving international co-ordination of data handling and use; in addition, continuously operating 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 programs, 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 Approve this report and request the IGCO Theme Team to use it in preparing the IGCO theme report.
2 Request SIT to review and confirm the commitments to existing and planned missions and programs (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 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 the its activities; and commit to responding to the TCO IT work plan within three months following its delivery.
