The purpose of this letter report is to state the findings and recommendations of the Climate Research Committee's (CRC) brief review of the U.S. contributions to the World Climate Research Programme (WCRP). The primary objectives of the review were to: (1) assess the coordination (national-international and project-to-project) of the U.S. scientific contributions to the WCRP; (2) identify potential science gaps and/or redundancies in the U.S. contributions to the WCRP, and; (3) identify existing or emerging issues and needs that might require more in-depth attention. Due to the limited time available for this review, the CRC focused on the first of these objectives.

A growing appreciation for how variations in climate affect society and the environment has increased the demand for fast and accurate predictions of climate variability. The Climate Variability and Predictability (CLIVAR) program, established internationally in 1995 and expanded to include a U.S. component in 1998, focuses on improving understanding and skill in predicting climate variability on seasonal to centennial time scales. This report evaluates the performance of the U.S. CLIVAR Project Office (PO) in fulfilling its charge from supporting agencies. The report concludes that the project office is vital for coordinating US CLIVAR activities and is effective despite limited resources. It also provides suggestions for enhancing the communications from and visibility of US CLIVAR activities and for developing strategic directions for the future.

The report reviews a draft strategic plan from the U.S. Climate Change Science Program, a program formed in 2002 to coordinate and direct U.S. efforts in climate change and global change research. The U.S. Climate Change Science Program incorporates the decade-old Global Change Research Program and adds a new component -the Climate Change Research Initiative-whose primary goal is to "measurably improve the integration of scientific knowledge, including measures of uncertainty, into effective decision support systems and resources."

During the past decade, scientists have learned much about the complex natural processes that influence climate variability and change, and our ability to model climate has increased significantly. We also have begun to better identify those parts of the climate system that are particularly important and not well understood and that therefore limit our ability to project the future evolution of Earth's climate. One of these critical areas is our understanding of the role of feedbacks in the climate system and their role in determining climate sensitivity. Feedbacks are processes in the climate system that can either amplify or dampen the system's response to changed forcings. This study looks at what is known and not known about climate change feedbacks and seeks to identify the feedback processes most in need of improved understanding. It identifies key observations needed to monitor and understand climate feedbacks, discusses ways to evaluate progress in understanding climate feedbacks, recommends ways to improve climate modeling and analysis for climate feedbacks research, and identifies priority areas for research.

The Gap Between Weather and Climate Forecasting: Sub-seasonal to Seasonal Prediction is an ideal reference for researchers and practitioners across the range of disciplines involved in the science, modeling, forecasting and application of this new frontier in sub-seasonal to seasonal (S2S) prediction. It provides an accessible, yet rigorous, introduction to the scientific principles and sources of predictability through the unique challenges of numerical simulation and forecasting with state-of-science modeling codes and supercomputers. Additional coverage includes the prospects for developing applications to trigger early action decisions to lessen weather catastrophes, minimize costly damage, and optimize operator decisions. The book consists of a set of contributed chapters solicited from experts and leaders in the fields of S2S predictability science, numerical modeling, operational forecasting, and developing application sectors. The introduction and conclusion, written by the co-editors, provides historical perspective, unique synthesis and prospects, and emerging opportunities in this exciting, complex and interdisciplinary field. Contains contributed chapters from leaders and experts in sub-seasonal to seasonal science, forecasting and applications Provides a one-stop shop for graduate students, academic and applied researchers, and practitioners in an emerging and interdisciplinary field Offers a synthesis of the state of S2S science through the use of concrete examples, enabling potential users of S2S forecasts to quickly grasp the potential for application in their own decision-making Includes a broad set of topics, illustrated with graphic examples, that highlight interdisciplinary linkages