Monitoring and prediction of the earth's climate: A future perspective

The climate is changing because of human activities and will continue to do so regardless of any mitigation actions. Available climate observations and information are also changing as technological advances take place. Accordingly, an overview is given of a much-needed potential climate information system that embraces a comprehensive observing system to observe and track changes and the forcings of the system as they occur, and that develops the ability to relate one to the other and understand changes and their origins. Observations need to be taken in ways that satisfy the climate monitoring principles and ensure long-term continuity, and that have the ability to discern small but persistent signals. Some benchmark observations are proposed to anchor space-based observations and trends, including a much-needed step forward in the quality of water vapor observations. Satellite observations must be calibrated and validated, with orbital decay and drift effects fully dealt with if possible, and adequate overlap to ensure continuity. The health of the monitoring system must be tracked and resources identified to address issues. Fields must be analyzed into global products and delivered to users while stakeholder needs are fully considered. Data should be appropriately archived with full and open access, along with metadata that fully describe the observing system status and environment in which it operates. Reanalysis of the records must be institutionalized along with continual assessment of impacts of new observing and analysis systems. Some products will be used to validate and improve models, as well as initialize models and predict future evolution on multiple time scales using ensembles. Attribution of changes to causes is essential, and it is vital to fully assess past changes and model performance and results in making predictions to help appraise reliability and assess impacts regionally on the environment, human activities, and sectors of the economy. In particular, a revolution in the way developing countries use and apply climate information is expected. Such a system will be invaluable and further provides a framework for setting priorities of new observations and related activities. Without the end-to-end process the investments will not deliver adequate return and our understanding will be much less than it would be otherwise.