Scientific analysis of the issues relative to detecting climate change, attributing causes to that change, and evaluating the consequences of projected climate change all require a robust, credible climate observing system. Observing systems are in place that partially fulfill the requirements for meeting these objectives, but the continued viability of some of these systems is questionable. Without immediate action to prevent the deterioration of some essential observing systems, the ability of the climate research community to provide over the next decade the objective scientific information required for informed decision making will be seriously compromised.

In the longer term, a new paradigm of observing and data management systems for the purposes of detecting and attributing climate change is required. The central purposes of the USGCRP cannot be achieved with limited-duration research observations supplemented with operational observing and data management systems whose mandate does not make long-term climate change observations a critical responsibility. Resolution of this problem requires those USGCRP agencies that operate observing systems expand the objectives of these systems to include climate observations as an equal partner with other operational requirements. A thorough review of procedures for operations and system changes should be made for each operational system to ensure that climate observing objectives are adequately served. Failure to pursue this recommendation will result in the continued struggle by USGCRP and other decision makers to distinguish between real observed climate change and artifacts produced by inadequate observing systems and data management practices.

The ten Climate Monitoring Principles should be implemented as a

matter of priority. The systems' performance should be monitored with corrective actions implemented as necessary. All these actions will require funding to ensure that the climate mission is a significant component of the work of all relevant operational agencies.

FINDING: There has been a lack of progress made by federal agencies responsible for climate observing systems, individually and collectively, in developing and maintaining a credible, integrated climate observing system, consequently limiting the ability to document adequately climate change.

RECOMMENDATION: To remedy this situation, it is essential that these agencies work through the USGCRP process and at higher government levels to accomplish the following actions:

• Stabilize the existing observational capability. In some instances, stabilization means nothing more than providing sufficient funding to continue programs. In others, substantial modernization of capabilities is essential because of both obsolescence and technological change. In still other instances, new capabilities are necessary to replace those lost in the recent past. Some stabilization will be relatively inexpensive (e.g., ensuring that climate records are accessible for processing), while others will require major funding (e.g., providing adequate definition of ocean variables or atmospheric water vapor).
• Identify critical variables that are either inadequately or not measured at all. Modeling and other theoretical studies are required to determine the adequacy of the spatial and temporal resolution required for observations of the critical variables. It is also essential to specify changes and variations at the appropriate spatial and temporal resolution for any additional climate variables that could provide society with the capacity to assess its vulnerability to climate variability and change, and to evaluate alternative adaptive measures.
• Build climate observing requirements into the operational programs as a high priority. Operational observation networks continue to be the backbone of climate measurements; significant parts of the climate observing requirements could be satisfied by these networks with only modest incremental costs. It is clearly not realistic to duplicate the global radiosonde network or the system of environmental satellites to provide a system dedicated solely to climate observations. Infrastructure support for these networks, including communications, procurement, and management, is most cost effective when consolidated into dual-use operational systems. However, the existing operational networks, while essential, are not sufficient for climate purposes: there are serious deficiencies both in the variables measured and the time and space scales employed. Moreover, climate needs do not receive sufficiently high priority by operational system managers to survive the effects of inevitable

• technological changes. Continuity, consistency, and homogeneity are essential for climate observations, but they have not been a priority for operational networks. Climate requirements that are not being satisfied should be incorporated into the operational programs as the most overall cost-effective solution.
• Revamp climate research programs and some climate-critical parts of operational observing programs. The ten principals for climate observation should be implemented. If the principles are followed, managers of operational and research observing systems can produce truly useful long-term climate data.
• Establish a funded activity for the development, implementation, and operation of climate-specific observational programs. Such an activity has two parts: (1) providing essential additional capability to operational observing systems and (2) generating a specialized climate observing capability.

The first part augments operational programs to ensure that data used for climate have the quality, coverage, resolution, continuity, timeliness, and stability required for climate change detection and attribution. This should include adequate studies of data requirements, including spatial and temporal resolution, as well as the required data assimilation studies. Additional variables should be added to the operational suite as needed (e.g., new or enhanced radiometers or data processing).

The second part provides for observing capabilities specific to climate, as a part of existing networks, if possible. This should include, for example, the sampling of trace gases distributed throughout the atmosphere; use of reference radiosondes at specified times and locations; identification of a subset of baseline; and reference stations from a larger network for special operating procedures. To the extent possible, this specific climate observational capability should be integrated into existing networks so that a cost for establishing and operating a parallel network is not incurred.

In the near term, the USGCRP agencies can ameliorate this situation by taking the following actions:

1. All agencies operating climate-relevant observation systems should adopt and implement the set of Climate Monitoring Principles outlined in question 4.
2. System performance measures should be developed and monitored on a regular basis. It would be unwise to wait for a major environmental assessment or data archeology effort to discover that problems that occurred 10 or 20 years earlier had already inflicted considerable damage on the climate record. An institutional infrastructure should be developed to assess the quality of data sets and correct problems as they occur.
3. Accelerate access by the research community to climate-related observation data bases, primarily in non-electronic formats, that reside deep in agency archives.

4. The free, open, and timely exchange of data should be a fundamental U.S. governmental policy and, to the fullest extent possible, should be enforced throughout every federal agency that holds climate-relevant data. Adherence to this principle should be promoted more effectively by the U.S. government in its international agreements, with particular attention given to implementation.
5. Vastly improved documentation of all changes in equipment, operations, and site factors in operational observing systems are required to build confidence in the time series of decadal-to-centennial climate change.
6. Establish and maintain strong, robust links between operational systems managers and the climate data users.
7. Because U.S. economic and social interests depend on knowing the climate globally, U.S. agencies should pursue international cooperation in climate observation and monitoring through international mechanisms. USAID funds may be one vehicle to ensure critical observations in developing countries.