The Global Energy and Water Cycle Experiment (GEWEX), which began in 1988 under the auspices of the World Climate Research Programme (WCRP), has completed its first phase and now is addressing its second phase science objectives. These objectives include: 1) producing consistent descriptions of the Earth's energy budget and water cycle and their variability and trends, and data sets for the validation of models; 2) enhancing the understanding of how energy and water cycle processes contribute to climate feedbacks, and 3) developing improved parameterizations encapsulating these processes and feedbacks for atmospheric circulation models.

Over the past 15 years, GEWEX accomplishments have included the development of continental scale experiments aimed at closing regional water and energy budgets; the production of long-term global data sets based on satellite data; the development of land surface schemes through model and data intercomparisons, and global data sets for model validation through the Coordinated Enhanced Observing Period (CEOP). These studies and projects not only address GEWEX Phase II objectives, but also enable GEWEX to effectively contribute to other climate and observational activities. In particular, assessments of GEWEX radiation products are being undertaken to determine their potential contribution to discussions on climate change. Furthermore, through CEOP and other global projects, GEWEX is contributing to a basic understanding of the observational requirements and the demonstration projects involved in the water-related activities of the Integrated Global Observing Strategy (IGOS) Partnership.