surprising the NOAA-sponsored and internationally supported International Research Institute for Climate Prediction (IRI) is not mentioned.

Does the plan reflect current scientific and technical understanding?

Generally yes. In some cases, however, the chapter does not sufficiently support specific claims (e.g., the statement that ocean mixing to a large degree controls the rate of projected global warming, CCSP, 2002, p. 71) or is incomplete (e.g., ice-albedo and vegetation feedbacks are not mentioned on page 71; the Antarctic Oscillation is neglected from the discussion on pages 72-74, CCSP, 2002).

Are the specific objectives clear and appropriate?

Generally yes. The chapter correctly identifies a need for Climate Process Teams (CPTs), a new strategy to bring key researchers together to rapidly improve the fundamental understanding of physical, chemical, and biological processes of the Earth system and how they are represented in models. The CPTs are intended to foster partnerships between scientists who specialize in observations, theory, and modeling so as to create an ongoing cycle of testing, verifying, and improving models in conjunction with research into climate processes. This new approach, and the general need to improve understanding of processes, could be better described in the plan, particularly by drawing from and referencing the CLIVAR science plan, where the idea was first presented.

The treatment of observations is uneven and in some cases weak. As discussed in Chapter 3 of this report the draft plan does not offer a structured program for building an integrated observing system for climate and climate-related variables. Indeed, it is awkward that the observation requirements are unclear until Chapter 12 of the draft plan. Chapter 6 of the plan does not explicitly identify the high-resolution observations necessary for process studies. In addition, it does not call for either an event-driven high-resolution observing program or a sustained high-resolution observation array to resolve the small spatial scales and fast time scales necessary to establish links between large-scale climate change and the strength of regional and local events. Chapter 6 does not adequately emphasize the role of data assimilation, reanalysis, and incorporation of remotely sensed observations in models. The reanalyses of the atmosphere by the National Centers for Environmental Prediction, the European Centre for Medium-Range Weather Forecasts, and other modeling centers provide consistent, gridded surface and atmospheric fields for 25 years that are increasingly used for climate research. With global climate observing systems being developed, such as the global ocean observing system, and new data available on land and in the ocean, this plan could be strengthened by including a clear U.S. strategy for producing atmosphere, ocean, land, and coupled system reanalyses.

Are the expected results and deliverables realistic given the available resources?

As discussed in the introduction to Part II of this report, this question is difficult to answer without detailed budget information. Nevertheless, the chapter does not adequately address the supporting research infrastructure needed to deliver the indicated products and payoffs. A fundamental gap in the U.S. research infrastructure exists in the transition of climate research tools, observations, and understanding to applications (e.g., NRC, 2000a). The plan could pay more attention to establishing ongoing, sustained mechanisms and computing resources for such transitions. This issue is particularly important in addressing question 5 in the draft Chapter 6, where two major challenges are not addressed: 1) the lack of ongoing partnerships between researchers and those producing operational model products; and 2) the interaction between the public and private sectors, particularly in terms of what climate products and services federally funded labs, investigators, and centers offer and what decision aids come from the private sector. Without the first it is difficult to see how a feedback loop would be established to improve the quality of model products. Without explicitly indicating the responsibilities of the public and private sectors it is difficult to assign any weight to the discussion of products and payoffs presented here.


This chapter is organized around five questions: (1) To what extent does the water cycle vary and change with time, and what are the internal mechanisms and external forcing factors, including human activities, responsible for variability and change? (2) How do feedback processes control the interactions between the global water cycle and other parts of the climate system (e.g., carbon cycle, energy), and how are these feedbacks changing over time? (3) What are the key uncertainties in seasonal to interannual predictions and long-term projections of water cycle variables, and what improvements are needed in global and regional models to reduce these uncertainties? (4) How do the water cycle and its variability affect the availability and quality of water supplied for human consumption, economic activity, agriculture, and natural ecosystems; and how do its interactions and variability affect sediment and nutrient transports, and the movement of toxic chemicals and other biogeochemical substances? and (5) What are the consequences of global water cycle variability and change at a range of temporal and spatial scales for human societies and ecosystems? How can the results of global water cycle

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