justify disregarding data prior to 1950. The observational record over North America is sufficient to infer trends beginning prior to the 1930s, when the most significant drought in the record occurred.

  • Line 18: Please see comment on Line 220 regarding the use of the phrase “hurricane activity.”

  • Line 21: Longer duration aggravates the impacts of heat waves, droughts, downpours, and to some extent tropical cyclones. This paragraph should be modified to reflect this consideration, consistent with statements in the body of the SAP.

  • Lines 29-30: Erosion and inundation of coastal lands are arbitrary selections of impacts. The committee suggests either removing these two impacts or expanding the list.

  • The Abstract should mention conclusions made within the body of the report on mid-latitude cyclones (blizzards or “nor’easters”), severe thunderstorms, and tornadoes. All other phenomena discussed in the report are mentioned in the abstract.


The committee suggests that a preface should not contain scientific or technical material; rather, it should provide background information and outline the process that led to the formulation of the document. In this case, the background information should outline purpose and goals of the U.S. Climate Change Science Program (CCSP) and the SAPs, and provide a brief summary of the purpose of SAP 3.3. The Preface in its current form does address the purpose of SAP 3.3; however background on the CCSP is absent. Remaining material of a technical nature should be moved to other sections of the document.

Specific Suggestions:

  • Display and discuss Figure 1 in Chapter 1 and in the Executive Summary, but not in the Preface.

  • Place Figure 2 in a “Box” and compare it to the analogous table in the IPCC assessments, by displaying the IPCC figure or via a description of that figure.

  • Acknowledge the similar Figure included in SAP 5.2, which was originally conceived to provide guidance for communicating uncertainty in the formulation of other SAPs. Note that SAP 5.2 is currently under revision but should be released publicly before SAP 3.3 is finalized.

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