types of drought (e.g., meteorological, hydrological, agricultural, etc…) and the uncertainties associated in quantifying drought severity using the Palmer Drought Severity Index (PDSI) and other indices. We note that PDSI is the only index discussed in the draft document. Furthermore, the document should address the uncertainty associated with climate model design (e.g., the model treatment of land-surface processes and parameters) and its impact on model representation of drought conditions.

8. The discussion of ecological impacts should be expanded. The draft briefly describes ecological impacts. It would be helpful to expand on these and carry them through with brief pointers, elsewhere in the document, particularly in discussions of future impacts in Chapter 3. The committee recognizes CCSP SAP Goal 4 addresses the subject of impacts in detail, but those SAPs address impacts of climate change in the broader sense and do not necessarily address per se the impacts of extreme events. SAP 3.3 should acknowledge the impacts addressed in other SAPs and incorporate some by example. Impacts to consider by example include wildfires and heat stress, which are “compound impacts” of temperature and moisture extremes.

9. The continuity and cohesion among the chapters needs improvement. The individual chapters read as stand-alone documents. They should be connected with some common themes and examples that are carried through (not just in terms of impacts as discussed in 8 above). There is a considerable amount of overlap and repetition, particularly between Chapters 2 and 3. Each chapter authorship team should coordinate with the other three teams to ensure that redundancies are eliminated.

10. The recommendations are not properly organized. Recommendations, and statements that are in effect recommendations but are not labeled as such, are scattered among the chapters. Some of these are repeated in Chapter 4 and some are not. Recommendations should be combined and contained only in Chapter 4 and a highlighted (bold) short sentence corresponding to each recommendation should appear in the Executive Summary.

11. The preface should not contain scientific or technical material. The Preface should contain “big-picture” information on the CCSP and the Synthesis and Assessment Products, and some background on the process and motivation pertaining to SAP 3.3. From a technical writing perspective, a preface is the appropriate location for framing and context; it should not contain technical information that is presented elsewhere in the report. Please see Chapter 3 of this review for more specific suggestions for content.

12. The content is limited in geographical scope. The rationale behind the minimal coverage of regions outside the North American mainland (e.g. “Hawaii, Caribbean, and U.S. Pacific Islands”) should be explained. The SAP focuses heavily on North America, but the prospectus and the title suggest some appreciable coverage of other geographic locations.

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