Appendix A
Compilation of Chapter-Specific Comments

GENERAL/CROSS-CUTTING COMMENTS

#      page/line
3 In general, the Preface, Executive Summary, and Introduction explain well the purpose of the report and what is in the document
4 The overall introduction to regional information is well written. The introduction to each region sets the stage for how that region has unique information needs and how they need to adapt and what are their particular vulnerabilities. The lead authors of each of these areas are well-known experts in their knowledge of the region, coming from academia, local, and federal agencies. Each region has unique attributes and information needs. The format for the regional sections was easy to understand and often pointed to the need for additional research. The “traceable accounts” and “key message” boxes provides easy-to-understand information with references that provide more detailed information. Adaptive and vulnerability information is spelled out in great detail, with clear estimates of observational and modeling trends. The examples of the interaction between climate scientists and stakeholders helped to make the information more relevant to particular regions.
5 The language of the sectoral chapters of the report is mostly of a succinct summary form which is nicely brought together through its use of “key messages” interpreted at the end of a section, along with discussion of uncertainties and confidence assessment. Because these key messages and the “confidence” assessment are such a great approach they should be a major focus for further improvement. Some of the deficiencies to note include:
6 a) between sections there is a less uniform structure than would be desirable;
7 b) some of the messages are given in such a hedged “on the one hand on the other hand” statement (or with such generality), that they have to be true. For example, see p.281 “could help” (or as a made up example similar to several in the report, “climate change may happen and if it does it could have an impact on agriculture”). It would be better to offer suggest positive, unhedged statements and then an appropriate degree of confidence given for them;


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  Appendix A Compilation of Chapter-Specific Comments GENERAL/CROSS-CUTTING COMMENTS # page/line 3 In general, the Preface, Executive Summary, and Introduction explain well the purpose of the report and what is in the document 4 The overall introduction to regional information is well written. The introduction to each region sets the stage for how that region has unique information needs and how they need to adapt and what are their particular vulnerabilities. The lead authors of each of these areas are well-known experts in their knowledge of the region, coming from academia, local, and federal agencies. Each region has unique attributes and information needs. The format for the regional sections was easy to understand and often pointed to the need for additional research. The “traceable accounts” and “key message” boxes provides easy-to- understand information with references that provide more detailed information. Adaptive and vulnerability information is spelled out in great detail, with clear estimates of observational and modeling trends. The examples of the interaction between climate scientists and stakeholders helped to make the information more relevant to particular regions. 5 The language of the sectoral chapters of the report is mostly of a succinct summary form which is nicely brought together through its use of “key messages” interpreted at the end of a section, along with discussion of uncertainties and confidence assessment. Because these key messages and the “confidence” assessment are such a great approach they should be a major focus for further improvement. Some of the deficiencies to note include: 6 a) between sections there is a less uniform structure than would be desirable; 7 b) some of the messages are given in such a hedged “on the one hand on the other hand” statement (or with such generality), that they have to be true. For example, see p.281 “could help” (or as a made up example similar to several in the report, “climate change may happen and if it does it could have an impact on agriculture”). It would be better to offer suggest positive, unhedged statements and then an appropriate degree of confidence given for them; 21

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22 Appendix A   8 c) not being clear as to what the confidence applies to (e.g. bottom of p 252). In some cases, the key message is subdivided for assessing uncertainty; and that seems like a good idea that might be further applied. (e.g. On p 279, the assessment appears to be only talking about Western U.S. but the key message also has a Eastern U.S. component). 9 d) Semantically misinforming phrasing: on p 280 “…confidence is high…climate change is projected to reduce forest CO2 intake.” There are similar constructions in many places earlier, (e.g, p 79,81,82,84). If something has been projected (e.g. by a model), it has been projected — no doubt about it. What is uncertain is whether the projection is correct. The phase above and other similar ones would work by simply dropping “projection” , i.e. “…climate change will reduce forest CO2”; 10 e) p 79 key message “…has occurred since 1980.” It is meaningless to talk of changes starting from a particular year, although ‘98 the big ENSO year seems popular among climate sceptics. 11 General point is that the key messages are an important communication device whose wording should be more carefully constructed than appears to now be the case 12 Assuming the main purpose of the NCA is to inform decision makers about choices for dealing with climate change and its expected effects, it is useful to see the report through the lens of some distinctions developed in the IPCC Special Report on Extreme Events (2012) and in NRC (2013): Climate and Social Stress: Implications for Security Analysis. Both those reports are focused on how to think about effects of climate change. These reports distinguish events, exposure, and vulnerability (and its elements: susceptibility to harm, coping, response, and recovery). The NCA appears to focus strongly on assessing events and exposures but does much less about assessing vulnerability. Yet for many decision makers, vulnerability is central because they want to reduce the harm caused by unavoidable, unpredictable events. Insufficient attention to vulnerability is thus a shortcoming of the NCA overall (though not of every chapter). This is not entirely the fault of the report’s authors; the USGCRP has not done much to build the base of research, data, and observations that is needed for assessing the vulnerability of sectors and regions. The consequences of this shortcoming of the Program are evident in the NCA report. 13 The draft largely focuses on negative impacts and risks posed by climate change, moving from experiences of weather-related impacts to modeled future trends in climate. The report does cover climate related risks of the sectors listed in Section 106. There is limited discussion of science uncertainty; for example limited discussion on the skill of models to make forecasts at different scales that would be useful for adaptation planning 14 The report largely does not put these trends in the context of other large changes expected to happen over the next century (economy, technology, health, and infrastructure). 15 The report is generally well written, but long and sometimes repetitive. The graphics while clear sometimes are not transparent as to the uncertainty or validity of results shown 16 While the report is long, there are many areas that could be covered and could add value. The report could put response to climate change in the context of other societal priorities,  

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Appendix A 23 and the priorities, capacities and institutions for each sector. The report largely does not highlight win-win steps to adaptation and mitigation or a prioritization of steps that should be taken. The sector chapters provide the opportunity to discuss such steps for adaptation which could be woven in an e-document with the adaptation chapter to make priorities clearer (otherwise each chapter is too short to develop ideas while at the same time the document is too long); it may be that this should be planned into an ongoing assessment process since it may be to difficult at this stage of preparing the report. 17 The report at times gives finding that appear different, and is some cases are different, than other assessments (notably the IPCC SREX and AR5 for which the first volume will appear at a similar time as this report). While there is a good effort in the report to give traceable accounts of confidence, these contrast with those of other assessments. In cases where there are apparent differences it is important to explain why, otherwise credibility will be compromised for this assessment and assessments more generally. As is the case with all impacts reports, it is important to be careful to avoid cherry-picking or its appearance (for example selecting a limited time series or specific metric from among many alternate choices); guidelines to avoid cherry-picking and describe how choices avoid bias, could be developed and applied in the report. 18 There needs to be a serious scrubbing in terms of terminology, grammar, and readability. 19 The key messages are in general more circumspect than the language in the body of the chapters. The authors need to be more thoughtful as to the “takeaways” in each chapter. There is a greater degree of certitude than is warranted. Many figures and text boxes are specific problem areas. Shrinking clams, increasing floods, etc. are eye-catching and they will become the prime messages, despite the caveats at the end. 20 The level of detail, literature reviewed, and breadth of issues discussed is generally appropriate for this assessment. While the authors did a good job of presenting individual facts, they were not always so careful in summary statements. Some of the key points were in jargon that would not be understandable to the public (without reading the main text, which should not be necessary). Some summary statements were phrased in an unscientific manner, and could be viewed as promoting an agenda rather than presenting factual summaries of the consensus of the scientific community (see specific comments below). There were also some issues where the effects of climate change were not sufficiently placed into the context of other human stressors—e.g. increased damage from sea level rise due to losses of protecting mangroves/wetlands/etc. The nature of impacts as INTERACTIONS of stressors was sometimes mentioned, but then not made clear for particular examples given. Treatment of CC as embedded within multiple other human drivers need to be consistent and clarified throughout. 21 Perhaps the report needs more emphasis on the effects of climate change elsewhere in the world on the U.S. A parochial example comes from the Michigan cherry industry which has several times, including last year, lost >90% of the crop as a result of an early warm period followed by frost. The infrastructure of the industry can remain viable when cherries are imported from Poland and the Ukraine. If those crops are also damaged then not only do  

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24 Appendix A   the growers have a very bad year but processors and others in the supply chain may shift away from cherries altogether. The world is increasingly telecoupled and these connections can both reduce vulnerability and offer new risks. 22 Perhaps there is a need for explaining how the science gets done. Many people who are persuadable but skeptical have a limited understanding of how we do science when studying complex systems. To the extent they have any science background it is often high school physics and chemistry where relatively simple, relatively linear and relatively isolated systems are the centerpiece. Some key points might include: (i) The study of climate change is not new—Tyndall’s work on heat trapping properties of CO2, Arrhenius s calculations of climate forcing from fossil fuel burning. What has changed is better understanding of process, better data, better models. (ii) Every major conclusion requires multiple lines of evidence. Models are very important but they are only one of about 7 lines of evidence that climate change is anthropogenic. (iii) Scientists are very careful about data. Much of the data is noisy and none is error free. Working out how to extract the signal from the noise is a major part of the scientific effort, and has been at least since Galileo. 23 It is fine to use model (in)consistency to indicate if the simulated projections are statistically significant and in a particular direction. But this is not the same as being able to say that the statistically significant change will in fact occur. One needs to test the downscaling methods using historical observational data. For instance, instead of using all observational historical data for calibration, it is better to use part of the historical data (e.g., before 1980) for model calibration, and use data from 1981-2010 to validate the downscaling methods in individual areas and regions. The NCA Report should at least show the multi-model mean differences, when data are available (e.g. for 1981-2010 minus 1951-1980; for 2041-2070 minus 1980-2000). Similarly, for emission scenarios (either SRES or RCP), observational historical data were used for their development (or calibration). The more appropriate approach would be to use part of the historical data (e.g., before 1980) for scenario development, and use data from 1981-2010 for validation. The NCA Report should demonstrate if the same methodology (in SRES or RCP) could realistically project the emission from 1981-2010 if we were at 1981 (with data available from 1980 and earlier). A potentially useful reference: Racherla et al., 2012: The added value to global model projections of climate change by dynamical downscaling: A case study over the continental U.S. using the GISS-ModelE2 and WRF models. JGR-Atmospheres, 117, doi: 10.1029/2012JD018091. 24 For climate scientists who, by definition, must take a systems perspective, the report is myopic in many regards, missing some key interconnections and history, and instead seeing everything through a climate change “lens.” This is not to say that climate change is unimportant, or that human activities are not driving much of this change. But we need an honest assessment of the interplay between the environment, policies, economics, and technology. Our models are not especially good at regional-scale predictions on decadal time scales, but this does not mean that the NCA cannot add value to the decision making process under uncertainty. The challenge is how to use uncertain science to inform these decisions and policies, while recognizing that science cannot provide definitive answers.  

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Appendix A 25 One needs to be cautious about taking simple regulatory approaches (that worked for sulfate emissions) to a much more complex and dispersed “wicked problem.” The impact of human activities on the environment goes far beyond the release of greenhouse gases into the atmosphere. Extinctions, declines in ecosystem services, etc. are driven by a range of activities, not just climate change. The report makes mention of these processes as its first crosscutting theme, but in general it assumes that climate change has (or will have) primacy. Multiple stressors are critical, but by taking such a climate-centric perspective, the report distorts the reality of these complex stressors and inadvertently sets up a perspective that reducing emissions will “solve” these problems. For example, the Northwest chapter discusses changes in forests (increasing fires, shifts in species composition, etc.) and declines in salmon populations without a straightforward acknowledgment that the dominant processes today are forest harvest practices and fire suppression (for forests) and hydroelectric dams (for salmon). By overemphasizing the role of climate change, the report may encourage one-sided solutions. 25 This complexity, when coupled with the uncertainty of our models (especially on a regional, decadal scale), reduces the utility of the assessment for policy makers and decision makers. Most decisions are looking 10-30 years out; even when the models project significant shifts, most of these are 50 years (or more) in the future. In this case, the whole issue of discount rates kicks in as well as the fact that other important (and equally uncertain) processes are equally critical (e.g., population decline, changes in energy technology, global-scale economic downturns, etc.). The report is amazingly optimistic about the quality of the regional-scale projections. The present CMIP process shows that the variability between the models within a scenario is as large as the variations between scenarios. When you go beyond temperature into variables such as precipitation, the models diverge even more and that they cannot replicate the observational record on a regional scale. This is not a criticism of the modeling community; these are difficult processes on challenging time and space scales. IPCC SREX chapter 3 is a good summary of climate extremes and the confidence in past trends and projections: [REF: IPCC/SREX. Chapter 3. Seneviratne, S. I., et al. “Changes in climate extremes and their impacts on the natural physical environment.” Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (2012): 109-230]. IPCC AR4 Chapter 11 (WG1) provides an assessment of regional climate change including temperature and precipitation indicating areas where the sign of precipitation change differs between models: [REF: Christensen, J. H. , et al. (2007): Regional climate projections, Climate Change, 2007: The Physical Science Basis. Contribution of Working group I to the Fourth Assessment Report of the IPCC , University Press, Cambridge, Chapter 11.] 26 From a decision support perspective, the present models really can only add another highly uncertain process to an already complex decision process. The uncertainties and variability are just too large. However, if the models could be used to identify how the statistics (frequency, persistence, intensity, etc.) of critical processes might change under climate change scenarios, that would be more valuable than detailed projections. There are some hints of this through the report, but how robust are these projections? And without any  

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26 Appendix A   estimates of the statistics of the projections themselves (in addition to the statistics of the particular processes, such as extreme precipitation), they are not of much value. As an example: A city planner from Chicago wants to know how freeze/thaw cycles might change under climate change, to make decisions about whether or not the city should change its repaving practices. Models might be able to make some projections but the confidence of these projections would be extremely low. A planner still might be able to use such knowledge, but it would need to be weighed against a variety of other uncertain projections (e.g., city finances, changes in traffic patterns, vehicle loads, etc.). 27 In the section about trends in flood magnitude. Fig. 2.20 (derived from Hirsch and Ryberg 2012) purports to show how flood magnitude trends change as a function of climate. Such information could be extremely useful to land use planners, insurance companies, water system managers, etc. But the Hirsch and Ryberg paper specifically states that: “The coterminous U.S. is divided into four large regions and stationary bootstrapping is used to evaluate if the patterns of these statistical associations are significantly different from what would be expected under the null hypothesis that flood magnitudes are independent of GM [global mean] CO2. In none of the four regions defined in this study is there strong statistical evidence for flood magnitudes increasing with increasing GMCO2.” They go on to state: “However, human influences associated with large numbers of very small impoundments and changes in land use also could play a role in changing flood magnitude. Unfortunately, at time scales on the order of a century, it is difficult to make a quantitative assessment of the changes in these factors over time.” That is, floods are both a natural phenomenon and a human phenomenon (land use, water management etc.) Although the draft has lots of waffling words (“suggests,” “possible” “contributed” etc.) the fact is that the public will ignore these nuanced phrases and come away with the impression that floods will increase. If the draft cannot get these facts right and if it glosses over model capabilities and limitations, then one must be skeptical of its outcomes. 28 Climate change is bound up in a poorly-understood complex of policy, economic, and environmental linkages. The notions of risks, vulnerabilities, and impacts and how they work together to help guide policy and investment are covered a bit in the Adaptation chapter, but they need to be woven throughout the report. For example, Hurricane Sandy is frequently brought out as an example of the types of disasters that will occur as the climate warms. Along with the NOAA time series of billion dollar disasters, the report convolves climate processes with complex financial and infrastructure processes. Smith and Katz show that the loss per billion dollar event has not increased (and perhaps has decreased), although the number of billion dollar events has increased somewhat. Thus storms are not necessarily getting more severe (in fact, we have been in a relative drought in terms of land- falling category 4/5 hurricanes) but it is likely that there is more infrastructure at risk and thus there are more events exceeding the billion dollar threshold. We need to temper our conclusions with the uncomfortable fact that our exposure has increased.  

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Appendix A 27 INTRODUCTION (LETTER TO THE AMERICAN PEOPLE) # page/line 30 P1 This introduction is very nicely written—very powerful, clear and unambiguous, particularly the first two paragraphs. 31 P1/L19-21 “... that is severe enough that some communities...” would sound better as “... so severe that some communities...” 32 P2/L1-3 Final paragraph, final sentence: Should this sentence include some reference to our national response? E.g., “...represent steps forward in advancing our understanding of that challenge, its far-reaching national and global implications, and the responses we are and should be making to reduce the threat”? 33 P1/L8 Perhaps add something like: “So, too, have fishermen and coastal planners …” 1. EXECUTIVE SUMMARY # Page/line 35 Generally reads as a scientific summary, with an effort to use non-specialist language. The latter is not entirely successful, so the accessibility to lay (including policy) readers is not as high as it might be. This may not be a problem if there are other summary documents in preparation. 36 The theme of a mismatch between infrastructure and the actual magnitude of weather fluctuations is one that can be extended easily. Managed systems, including agricultural and forest lands and fisheries, are also structured in specific ways, such as reliance on irrigation, and these structures are also vulnerable because they are part of the infrastructure of those managed systems. In addition, unmanaged systems such as watersheds and protected areas have an internal ecological structure (“natural infrastructure”) that is also disrupted by events in a changing climate. This is a time when many are focused on infrastructure (e.g., because of Sandy), so the extension of the concept to ecosystems of importance to humans is worth considering in a high- level summary. 37 P3/L25 “variation” not variability seems to be intended 38 P6/L22-25 Sentence is garbled. Delete 2nd “and” in 24? 39 P.11/Table Table should have a brief caption indicating the basis for selecting observations for inclusion — e.g., to illustrate trends unfolding over times of decades. 40 P12/L8 Not clear what is meant by “local economies”; the other items in the list might have in common that they are sources of stresses. If that is what is intended, the passage  

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28 Appendix A   # Page/line should say so. 41 P19/L3-6 This paragraph suggests to the lay reader that the relative contributions of China, India, and other emerging economies play a key role in the evolution of American climate conditions. Is that taken up in the chapters? 42 The lack of confidence language raises concern. 43 Report Findings is missing a key finding re R&D needs. 44 Inconsistent in treatment of future precipitation. P4 refers to increased precip vs P5 to “reduced water supply.” 45 Verb tenses are inconsistent, particularly in health section vs others. 46 P7 refers to Greenland and Antartica without clear implications for U.S. 47 Health Section : Increased risk of zoonotic disease in many regions should be mentioned. 48 P7/L28 Is drought an issue in the Great Lakes? 49 P8 Should the conclusion on climate change be supported here only by temperature changes. Citing multiple lines of evidence from multiple types of observations seems more compelling even in this brief statement. 50 P9/L33-34 The vulnerability of increased irrigation to drought and the conflicts over water use should be noted even here to highlight the cross-sectoral interactions. They are too often ignored. 51 P10 It seems odd to single out only disaster modification among ecosystem services. 52 P4/L28 not clear what was satellite and what wasn’t, given the longer time frame 53 This traditional Executive Summary is not effective at communicating to a broad range of readers the information contained in the draft report, particularly given the controversy and complexity of the issues covered. The text requires more than a basic understanding of climate change and its associated vocabulary. 54 Several phrases early in the Summary assign responsibility for climate change to human activities, but the text lacks background information to inform/prepare the lay reader to digest these assertions For example, p. 3, l. 6: The phrase “which is primarily driven by human activity” needs more justification/introduction. Suggest adding “predominantly the burning of fossil fuels.”  

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Appendix A 29 # Page/line 55 Authors should consider adding a sentence or two very early, i.e. paragraph 1 or 2, describing the connection/relative scales of “human-induced warming” and “a naturally varying climate.” 56 Discussion of risk and uncertainty is not addressed in the Executive Summary, until p. 13, l. 1. These issues should be addressed earlier in the text. 57 P6/L21 Is there any information to show that we are on track to exceed A2 either from the U.S. contribution or globally? Information in this section should be supported by some part of the 1100 page report 58 P12/L8 What does “local economies” mean. How is “local economies” a stress factor? They are part of the context for understanding the impacts. 59 P12/L19 Such as? Which recent events? Need to give an example. 60 P13 The whole bullet 4. on tipping points is vague regarding what these break-points might entail. A concrete example would be useful. 61 The most important content in the executive summary is found in the Report Findings section. Perhaps move this to the beginning so that it’s the first thing readers encounter. The content that is currently at the beginning of the executive summary reads like the introduction to the report, rather than a summary of its most important points. 62 P5 second paragraph: The sentence that begins “Some of the key drivers of health impacts include...” is quite long and a bit hard to understand. Either use bullets or divide the sentence into several sentences. 63 P5 third paragraph: “Iconic species” will not be understood by many lay readers, and the last phrase of the sentence (“...the potential for extreme events...” is vague. 64 P5 fourth paragraph: Perhaps add “leading to contaminated water supplies,” or something like that at the very end of the paragraph. 65 P6 second full paragraph: There’s a verb missing: “Voluntary efforts, the recent shift from coal to natural gas... and federal programs are underway and have...” 66 Crosscutting themes and issues, #1: The last sentence states, “As illustrated by recent events...”—please specify. 67 Report finding #4: At the end of the last sentence, the authors state that heat-trapping gases are strongly reduced. This seems to be the wrong word—dramatically or greatly perhaps? 68 Report finding #4, second sentence: “Same” should be changed to “some.” Should human choices be added to the sources of uncertainty cited in the last sentence? 69 Report finding #5: Many lay readers won’t understand what is meant by “food  

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30 Appendix A   # Page/line security.” And a couple examples of “unfamiliar health threats” would be helpful. 70 Report finding #5: Much of this section may be difficult for many lay readers. For example, “probability of occurrence of a certain type of event” could be stated more simply as “how often an event will happen,” and “exceeding a particular threshold” could be re-stated as “how severe it will be.” 71 P3/L11 Characterizing the impacts simply as “disruptive” here conveys a very different notion than the message conveyed by the report itself. “Disruptive” suggests something that is temporary, where one ultimately settles into a new equilibrium (e.g., it is disruptive to move from one city to another). While there will certainly be disruption, it is the significant costs incurred as a result of that adjustment period that are important. That idea is not captured by characterizing the changes simply as disruptive. 72 P3/L14 This sentence is unclear. It is not clear how using scientific information will provide economic opportunities. 73 P5/L1 It is not clear what the word “stresses” is intended to convey in this paragraph. For example, what are “stresses” on “existing social, institutional and legal agreements”? The word is used multiple times in this paragraph, but I don’t think the lay reader will have a clear idea of what it means here. 74 P5/L8 There is a discussion here of negative health impacts. It should also be acknowledged that warming could yeld some positive health impacts as well, for example, in areas where exposure to cold (or inadequate access to heat) has negative health impacts. 75 P5/L20 What does it mean to maintain “a robust public health infrastructure”? One might interpret this as some type of public provision of health services (nationalized health care??). Is that what is intended? 76 P6/L18 Replace “worst” with “largest”? The largest changes are not necessarily the most costly (i.e., worst) ones. For example, large changes for which there is low-cost adaptation may not impose large costs. 77 P6/L41 The reference to economic opportunities provided by being prepared is unclear. This is the second place in the exectutive summary where this idea is mentioned, and in both places one is left wondering what this is intended to convey. It almost sounds like individuals can be opportunistic and take advantage of (make some money off) other people’s vulnerability to climate change. That is probably not what is intended, so some clarification is needed here and above. 78 P8/L31 When referencing the costs that are already high, it would be helpful to be a little more specific about what costs have actually been already observed/documented (as opposed to those costs that are projected to occur in the future). 79 P8/L36 There is no mention of “threats to mental health” in the discussion up to this point, so it is surprising to see it here as part of a major finding. And there is nothing in the  

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Appendix A 31 # Page/line paragraph here that clarifies what is meant by this. It is also unclear what “unfamiliar health threats” (line 41) refers to. And if they are reemerging, then how can they be unfamiliar? Some clarification is needed here. 80 P9/L37 The statement that yields of major crops are expected to decline, “threatening both U.S. and international food security” may be true, but it doesn’t follow logically. A reduction in U.S. crop yields does not necessarily constitute a threat to food security. To threaten food security, the impact has to be large and not offset by an increase somewhere else. So just saying there will be a yield reduction is not sufficient to support a statement about a threat to food security. 81 P10/L24 The text references “large social, environmental, and economic consequences.” However, most of the discussion in the report identifies impacts but does not QUANTIFY those impacts, especially economic impacts, and so it is hard to determine (from the report) which impacts will be large and which will be small, which will be economically significant and which will not, etc. The report very thorough documents impacts that have been shown to exist (under either current climate or projected future climate) but does not provide much information on which of these many actual or potential impacts are most significant/important. This is obviously much more difficult to determine, but it is essential for focusing attention on particular concerns. 82 P11/Table In the Northeast row, it’s surprising not to see mention of the economic impact on, for example, recreation. 83 P12/L3 Again, the word “stresses” is used here, while in line 6 the terminology “multiple factors” is used. Are all factors necessarily “stresses”? It seems the key point is that other things are changing as well, and these other changes combine with the climate changes to determine outcomes. 84 P12/L24 This is the first reference to a “risk-based framing” for the chapters in the report. This, along with the instruction to focus on most significant impacts, seems to be a key framing issue for the report as a whole. As such, it seems this statement should appear at the very beginning of the executive summary rather that at the very end. 85 P13/L1 The introduction paragraph to this section on p. 12 (lines 2-5) lists three themes, but then one turns the page and finds two additional themes. Is there a reason to highlight themes 1-3 in the opening paragraph but not 4-5? 86 P13/L2-11 The point could be made here that, not only are tipping points difficult to predict, but their existence can have important implications for management decisions. They make it much more difficult (and important) to design appropriate mitigation and adaptation policies. 87 P13/L19 The discussion of this cross-cutting theme seems out of proportion to the others. It could be condensed considerably. For example, everything from line 19 and below could be deleted without losing the main point.  

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98 Appendix A   # page/line adaptation (see, for example, the NRC report Facing Hazards and Disasters: Understanding Human Dimensions). The authors could have placed more emphasis on these natural connections. For example, the extreme events literature contains typologies of forms of adaptation and provides important insights on barriers to the adoption and implementation of loss-reduction measures for extreme events such as hurricanes and floods, as well as factors that facilitate adaptation, such as state-level enabling legislation and the presence of loss-reduction coalitions and advocates. The U.S. has done more of this kind of research than any other country, beginning with the seminal work of geographer Gilbert White, and this literature should be tapped for its many insights. 642 It is surprising that the chapter’s discussions on barriers to implementation of adaptation action make no mention of the fact that there are organized movements in the U.S. that oppose climate change adaptation. This is a politically sensitive topic, but it is intellectually problematic to argue that “lack of funding, policy and legal impediments, and difficulty in anticipating climate-related changes at local scales” constitute important barriers without also noting that in the U. S. there are groups that actively oppose such measures, because they are framed as part of the U. N.’s “Agenda 21,” or advocated by ICLEI, or because adaptive measures interfere with property rights, or because they could constitute illegal “takings.” Including this kind of information in the NCA may be viewed as a non-starter, but the fact remains that a number of politically active local groups have opposed climate change adaptation measures on these grounds, and there are movements that oppose sustainable growth and development planning, comprehensive land-use planning, and other measures that could include climate change adaptation. This opposition is an empirical fact, and it should be acknowledged in the NCA. Like other chapters in the report, this one is curiously devoid of references to the political and economic interests that are active in the climate change arena. The avoidance of these empirical facts is understandable, but it results in an incomplete picture of the current climate-change action landscape 643 P984/L17 Update building and landscaping codes to “protect against disease vectors?” This seems like a stretch. 644 P995 It’s reasonable to talk about risks, but shouldn’t we be balanced? What about the opportunities? Risk is something that all businesses face, and it’s hard to make a compelling case for risks given our high level of uncertainty. However, we might think about the opportunity space. 645 P1000 The discussion of the adaptation process is geared towards agencies and large businesses that either have the mandate or the capital and staff to play in the climate adaptation arena. We should think about how do we engage a broader spectrum of organizations and businesses. The present approach does not downscales to these smaller entities.  

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Appendix A 99 # page/line 646 The NIDIS discussion is very good, but in a way it is a counterexample to the approaches laid out. It worked because it had a clear and understandable focus on an issue that affects a wide spectrum of organizations. Climate adaptation is broad and diffuse, operates over a range of time and space scales, and it is convolved with a range of other processes. Think about flood control. It is tied into water rights, amounts of impervious surfaces, the National Flood Insurance Program as well as the natural environment. On the other hand, drought is really focused on the amount of water available. The problem is how to distribute a limited resource. Floods and their impacts are much more interlinked between the social and natural worlds. Perhaps the lesson learned from NIDIS is that it worked because it was bounded in its scope. 647 This chapter is very well-written, well-organized, and easily accessible to lay readers. The glossary at the start of the chapter was quite helpful; it would be good to see other chapters follow this example. The tables summarizing the various types of adaptation actions taking place give the reader a clear sense of the scope and variety of the national response. 29. RESEARCH AGENDA FOR CLIMATE CHANGE SCIENCE # page/line 649 This chapter seems to build strongly upon the America’s Climate Choices and USGCRP strategic plan documents. There is strong emphasis on adaptation science and decision support, while mitigation seems to be given less emphasis. 650 It would be useful to identify existing agency research programs that are pursuing these objectives in whole or part. The reader unfamiliar with federal research may perceive these priorities as new, even though significant work is already underway. 651 P1038/L15-16 Particularly in light of the priority set on traditional knowledge (ll. 20-23), there should be studies of community-based natural resource management arrangements and the conditions under which they are effective. 652 P1041/L18-29 In light of the intense focus on job creation in public policy discussions, it would seem useful to include studies of labor markets. One has the (not well informed) impression that much of the growth in employment in environmentally related job specialties over the past half century originates in widening regulation of environmentally consequential activities. If, as some expect, growth in that and other aspects of the public sector is constrained in the future, the capacities described here will need to arise from private sector and civil society demand. That possibility could be illuminated through studies of the labor market.  

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100 Appendix A   # page/line 653 The goals as structured, do not address the criticality of integrating adaptation and mitigation. Further goal 7 does not warrant self standing. It is a sub element of either 5 or should fit elsewhere. 654 Is there a rationale for the ordering of the research areas identified? If they are not in a priority order, then that should be said. And they will have more impact if they are not listed in the same general order that they have been in previous reports. 655 In a time of stable or declining budgets, it would be very helpful to get priorities from a process like the National Assessment. Having just completed this huge and very well done exercise, no one is in a better place to make recommendations about what research is most needed to make the ongoing assessment process better. A list of 37 equal priorities is only of modest help. 656 Because of the heavy involvement of federal agencies, it would be useful for the research recommendations to indicate how they could be handled by existing programs and where new initiatives would be needed. For example, given RISAs, RCAs, CSCs, etc., who might effectively take up what part of the research agenda? 657 P1036/L21-28 If the goal is to provide better projections, then the better understanding of uncertainties needs to consider uncertainties in emissions scenarios that come from projections of population change, economic growth, technological change, preferences, etc. It seems appropriate to understand how much of uncertainty in future projections comes from the climate system (and our models of it) and how much comes from uncertainty about emissions trajectories. The contributions to uncertainty will of course vary depending on what is being predicted over what time scale and at what spatial resolution. 658 P1037/L7-8 This bullet deals with a critically important and complex line of research and needs a few sentences of elaboration. Also, the term “experiments” is not clear. To some disciplines experiments involve randomization and control groups, to other disciplines an experiment is large scale coordinated data collection. The former kind of experiment will play little role in expanding our understanding of the effects that are the point here. 659 P1037/L9-11 Tipping points and thresholds are important not just in climate systems but in coupled human and natural systems and need to be studied with high priority. 660 P1037/L12-15 The phrasing here is hard to follow: The importance for various kinds of decision making of various types and sources of uncertainty? 661 P1037 The difference between bullets 1 and 3 is not clear. Bullet 2 on federal clearinghouses (not sure what is meant, examples?) seems of much more narrow scope that the other priorities in this list. Bullet 4 mixes what is largely a problem in physical climate sciences (how well do various approaches to downscaling work?) with a social/ policy sciences question (what’s the best way to deploy such information and what information is really needed?). They are related but different people would actually  

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Appendix A 101 # page/line do the work for each, perhaps informing each other. On the last bullet: while it would be neat to know more about these strategies, to what extent are they actually useful, given the current technological organization of our communities? They may be very relevant, but the case should be made, as it’s not obvious. 662 P1038/L26-28 This makes it seem as if energy technology and economics are all that matter, when a variety of other social factors are important drivers of GHG emissions and human responses to climate change. See comments on the mitigation chapter. 663 P1039/L1-3 What is meant by “socio-economic analyses?” 664 P1039/L4-6 This seems very narrow compared to the rest of the items on the list. 665 P1039/L7-9 Why only with regard to mitigation? Why not drivers overall and decisions about adaptation? 666 P1039 Research Goal 4. It is admirable that the need for social data is mentioned at least in passing. But this needs elaboration. The social data needed is the only data on this list that is an orphan—with no federal agency in the GCRP with responsibility for it. What is needed should be specified in more detail. Specifying what is needed is essential given the lack of engagement with this kind of data by the GCRP agencies. Bullet 1 has the same problem—a mention without enough detail for anything operational to happen. 667 P1040/L17-20 While “socio-economic issues” (what this means is not entirely clear) influence use of information, so do cognitive factors on how people process information which makes the way in which information is generated and provided of great importance. As this para is phrased I don’t see that considered. 668 P1040 Bullet 1: It’s not clear whether this is about research on how to communicate effectively on the things in the list that follows (e.g. transferable vulnerability assessment techniques) or it’s about research on the processes listed themselves (e.g. improved understanding of consumption patterns and environmental consequences). 669 P1041/L31-37 Current education seldom provides an understanding of coupled human and natural systems. What is the rationale for the particular list given here at the end of the bullet point. For example, why only “economic” sustainability? 670 P1041/L33 Better to say “biological, physical and social” 671 P1042/L2-5 What about historically black colleges/universities? I would suspect that any vulnerability analysis would show that the African-American community also has high vulnerability and is underrepresented in the appropriate sciences. 672 P1042 Research Goal 7. Certainly much more can be done with scenarios. But it’s not clear how much of what is called for involves “downscaled” scenarios for levels of decision making involved in adaptation and resilience building. If that is intended, then some  

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102 Appendix A   # page/line discussion of the sharp rise in scenario uncertainty at the local to regional level is warranted. We are finding that downscaled climate models may not have sufficient skill to be useful for some key parameters in some regions, and the same may well be found for downscaled scenarios. Or perhaps what is meant is that given the importance of scenario uncertainty in generating uncertainty in projecting climate change and impacts, better global scenarios are needed because when one follows the chain of analysis down to the local to regional level, this would aid in adaptation planning. 673 Title does not reflect content in this chapter. The content focuses on research for the assessment process, but there is reason to be skeptical that research to support assessment is the same as research that actually can be transitioned into tools for decision-makers, products and policies that allow societies to make adaptation decisions, and investments that will lead to new energy and water systems. 674 While the chapter talks about more research on impacts and risk assessment, it does not take the step of the research needed to identify and quantify vulnerabilities and options for societal action. The latter would begin to engage communities, engineers, and scientists. 675 P1036 Research goal 1: The high priority research goal 1 needs do not mention ocean/coastal marine resource impacts and vulnerabilities. Going through the list: 676 P1036/L25-28 Missing coastal environments and healthy ocean 677 P1036/L29-34 Ocean circulation also important for not only global transfer of heat but also water cycle and carbon cycle 678 P1037/L1-6 Does not mention any of the ocean stressors: pollution, fishing practices, unsustainable resource extraction 679 P1037/L26 It is not just sea level change that produces risk but also the compounding effect of increased probabilities of storm surge from extreme events. 680 P1037/L17-19 Missing the largest part of the water cycle—the ocean—and the impact it might have on water availability (monsoons, etc) 681 Research Goal 2: The terms risk, vulnerability, adaptation, resilience are all used here and require some good definitions. Many of these bullets are not what one would necessarily call a research agenda, but rather are capacity building. It is surprising that indigenous knowledge is mentioned but not other experiential based knowledge. 682 Research Goal 3: It’s not clear how many of these bullets are going to lead to the exploration of options and actions. In order to better link the fate of carbon emissions with effectiveness and timescales of mitigation measures we need to have some proposed mitigation measures. The second bullet refers to land-based decision- making but is completely missing the increasing use of the ocean and coastal resources. The 4th and 5th bullets call out for “understanding” but how is this  

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Appendix A 103 # page/line understanding going to lead to action. Again, in the 5th bullet there should be mention of ocean energy development and water availability impacts. 683 Research Goal 4: Missing critical ocean state variables, extreme events, and the lack of an integrated coastal ocean observing system. There is no discussion of needed essential variables. 684 Research Goal 5: Is this list carried out via “desk studies” or does it require real experiments? 685 Research Goal 6: Why are Native American colleges and universities called out but not other minority institutions? 686 Research Goal 7: It seems as though this goal should include something about responsibilities at various levels (Local, state governments; industry; public; communities). 687 Research Goal 1: The only mention of health in this section is “healthy wetlands” (line 27) 688 Research Goal 4: Indicators should include trends and changes in all environmentally sensitive infectious diseases in addition to those that are vector-borne. 689 Overall, this chapter seems to take a different approach to social science than Advancing the Science of Climate Change or the GCRP Strategic Plan. Rather than being highlighted and identified as a priority in which there has been little investment and relatively little commitment by agencies, social science is there most often by inference in some of the topics mentioned. Perhaps this is because the authoring team included only two social scientists, both geographers who are world class experts on adaptation. So to them the need for social science efforts to address some of the topics listed is obvious, but this may not be true of the GCRP/ NCA agencies who have very limited social science capacity and thus struggle to include it despite apparently good intentions. One could argue that the NCA has to again make the point that we cannot carry out the research needed without a serious commitment to and investment in the kinds of social science research needed to support the overall agenda. 690 P1039-40 The absence of specific identification of the kinds of social science data needed is strking. 691 If the NCA is not capable of looking across the issues discussed and identifying research priorities, I wonder who would ever be in a position to do so. Granted the immense amount of work undertaken may not have left time to hammer out a consensus on research priorities. But for all the good work we have seen with the NCA and the GCRP strategic plan, we still have no set of research priorities, only lists. These lists are not as integrative as the ones available in the ACC reports. To be sure, the NCA is not the activity to adjudicate the relative priorities to be given to  

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104 Appendix A   # page/line basic science, mitigation and adaptation. But within the realm of adaptation/ vulnerability/ resilience it is well poised to say what is needed to do a better job in 5 years and 10 years. 30. THE NCA LONG-TERM PROCESS # page/line 693 P1050/L6 Since “a much larger effort” is proposed, it would be helpful to know which audiences are targeted now, and the rough cost estimated for the web and communications effort. NASA’s effort to gain users for its satellite data may be a useful benchmark. 694 Overall, language is cautious and unclear about the goals, breadth and depth of a sustained process. E.g. p 1048; lines 9-13. 695 P1049/L13- Should include “other energy-economic-climate models” not just IAMs. “projects’ are 15 referred to as “infrastructure”; this seems odd. Line 32 refers to “utility and timeliness of future synthesis reports” vs perhaps “informing robust decision making.” 696 P1050 Refers to “two-way” communication ‘among partners” vs “effective communications.” 697 The chapter does not make clear why we should have sustained assessments. How have assessments been used? What have been the tangible outcomes? What has changed in terms of taking action that incorporates climate change information in the multitude of decisions that are made? What new information products have come out of the assessment that is being sustained? 698 In this chapter the sustained assessments are to “evaluate the nation’s vulnerabilities to climate variability and change and its capacity to respond.” If this is the vision then one would expect the research agenda to be very different than what was proposed in the previous chapter. Also such an evaluation would require very different assessment than what has been done. However in lines 31-36t it would appear that the sustained assessment would be more of the same, rather academic, assessment strategy that currently is being used. 699 Sustained assessment of health impacts and adaptation must adopt a more comprehensive coverage of disease threats in addition to direct impacts (heat stress, allergy, mental health, etc.). This would require a multidisciplinary effort within the health sector (environmental health and infectious diseases) and cross-sectoral efforts between the health sector and ecosystems science, biodiversity, hydrology, forestry, etc, as well as capacity building.  

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Appendix A 105 APPENDIX 1: COMMONLY ASKED QUESTIONS # page/line 701 This may be one of the most-read sections of the report because informal science educators are asked these questions all the time, and many are nervous about responding to skeptics—particularly when they’re in front of an audience. The questions and answers are clear and simple, and they explain the science in terms that most people would understand. 702 It would be helpful to have definitions available for some terms—either by links, footnotes, or a glossary. Photographs would also be a useful addition for the people who struggle with charts and graphs (sea ice shrinkage, glaciers melting, etc.). 703 One of the most common misconceptions in the U.S. is that the scientific community is in widespread disagreement about the reality and causes of climate change (36%, as of Sept. 2012). The appendix has an excellent section clarifying the scientific consensus (CAQ J). But it would be good to see the text of the question be re-stated in terms of this issue, i.e., “Isn’t there a lot of disagreement among scientists about whether climate change is happening and whether humans are causing it?” 704 Terms that need definitions for lay readers: forcings, radiative, proxy data, feedback, infrared spectrum. 705 P1057 CAQ A: The text explaining the difference between weather and climate is excellent. It would be useful to expand the final paragraph, which is goes to the heart of the question. 706 P1065 CAQ D: The final paragraph refers to the “warmest winter everywhere except in the Southeast.” Should this say “...everywhere in the U.S. except...”? 707 P1067 CAQ E: The authors might consider adding a sentence stating how long emissions stay in the atmosphere; it brings home the point that rapid action is needed. 708 P1068 Figure 8: This is a great figure, but another showing just the U.S. would be a good addition. With a U.S. map, readers would be able to identify their home state, and everything that helps localize the issue for readers can increase their readiness to support mitigation efforts. 709 P1068 Figures 8 & 9: The two figures appear to be in conflict: Figure 8 shows no warming in the Southeast, but Figure 9 shows the region as increasing by about 1 degree. Figure 9 also appears to have a small error in the vertical axis, i.e., a -.05 above zero, as well as below it. 710 P1070 CAQ F: The second paragraph states that heat-trapping gases are transparent to the sun’s energy, but opaque to the heat radiating back from earth—the lay reader wonders why that would be so. A sentence or two clarifying the difference would be helpful, and can actually be found in the answer to the next question (i.e., G, third paragraph). Perhaps readers could be referred to G for further information. 711 P1074 CAQ H: This answer is particularly nice. The question is raised so often, and this answer refutes it clearly, simply and directly.  

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106 Appendix A   # page/line 712 P1076 CAQ I: An example or two would help lay readers understand the research being described here. The last sentence of the answer (increasing likelihood of extreme weather) could be dropped because it doesn’t address the question. 713 P1078 Figure 14: The data are impressive; I’d suggest deleting the map that is behind the graphs to make the page less busy and easier to read. 714 P1080 CAQ J: A climate skeptic could say in response to the last paragraph, well, how can you be so sure climate change will be harmful when you don’t know how sensitive the climate is to emissions, how emissions affect clouds, etc. While acknowledging what we don’t know is important, it’s also critical that we don’t give the skeptics more ammunition. Would it be possible to include what is known in all these areas? E.g., “We know sea levels will rise, but don’t know exactly how much—somewhere between one and four feet over this century.” The point made in the last sentence in the response to CAQ S would bear repeating here. 715 P1081 Figure 15: This figure is very complex and contains many terms that lay readers won’t understand. Anything that can be done to simplify the figure would be helpful. 716 P1082 Figure 16: The figure is redundant with Figure 14. Most readers probably won’t read all the questions in the appendix, however, so the redundancy may not be a real problem. 717 P1083 CAQ K: Again, an excellent response to one of the assertions often made by skeptics. 718 P1076/L16 Are there attribution studies that actually conclude it is impossible to explain many aspects of warming without human activities ? (EU heat wave in previous sentence is an example). 719 The use of questions is an effective communication tool, however, the choice of questions, tone, and lack of rigor can be both polarizing and argumentative and can detract from the credibility of the NCA. The questions largely are about climate science and not about the assessment for the U.S.; given the general nature of the questions, there are ample other sources of such information (for example, the IPCC assessments). And in some cases the informal answers (e.g. using analogies) can lead to inaccurate overgeneralization of scientific evidence. 720 The figures are not referenced in the text answers to the questions; and the captions, referencing, and traceable accounts are incomplete. 721 P1057/L15 The comparison between human choices and climate variability is a poor analogy for climate statistics especially since it has been argued by some (and perhaps in the NCA) that emissions scenarios cannot be assigned a probability. Suggest avoiding such analogies and focusing on climate. 722 P1057/L26 Asserting that we know the physics “relatively well” does not present a clear basis for the answer to the question. The lack of assessment of uncertainty of projections in the NCA and such a simple assertion leaves a very weak basis for the reader.  

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Appendix A 107 # page/line 723 P1058/L3 The figure does not fit the caption. For example, there are no day to day changes in the figure. 724 P1067/L18 Text erroneously states that the last decade (unequivocally) is the warmest in 2000 years. Analyses have attempted to answer this question and have estimated the likelihood that this may be true. 725 P1067/L22 This an overgeneralization (e.g. the specific time context is not given and therefore it may or may not be true) and does not apply to all time periods; the Earth has had periods of warming and cooling. 726 P1074/L16 Suggest removing “exactly”; pattern matches are not exact. 727 P1076/L16 Attribution studies have not found unequivocal results therefore “impossible” is incorrect. 728 P1076/L19 Attribution of extremes is of very limited confidence as assessed by the SREX. For example, SREX states (p9) “only low confidence of the attribution of any detectable changes in tropical cyclone activity to anthropogenic influences.” 729 P1077/L3 It is incorrect to claim attribution is certain for the systems in the figure. Even for temperature, attribution is a probability statement (e.g. very likely). For other features (e.g. floods), ability to attribute to climate (and other factors) is much poorer. 730 P1078/L2 The certainty of the assertion “only” in the figure and caption is not consistent with attribution studies or IPCC conclusions. 731 P1080/L16 “nothing short of remarkable” and 97% without reference seems argumentative. 732 P1085/L8 Suggest that the trend for both Antarctica and arctic sea ice be quantitatively described instead of saying simply “little trend.” 733 P1088/L1 This seems like a very small set of papers considering how many on climate change are published? 734 P1089/L10 “cannot be altered” is not true; it is insensitive to greenhouse gas emission reduction. 735 P1089/L25 12F is higher than shown in the chart on page 25 (or about 4C given in the scientific literature); why are uncertainties not given for all projections? 736 P1090/L7 Since no uncertainty is shown in the curves, one cannot tell how to compare sensitivity to scenario to uncertainty. Caption is confusing since only scenarios are mentioned. It is not mentioned how the curve is derived from models (median, average, ?). 737 P1091/L10 “many areas” is not consistent with the IPCC SREX which assessed that this may occur in some areas with medium to low confidence. Overconfidence is expressed with regards to projections of extremes throughout the NCA. 738 P1091/L16 “has clearly increased” implies high confidence in attribution which is not true for most weather extremes. This should state precisely for which extremes there is high  

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108 Appendix A   # page/line confidence attribution, otherwise this is providing misinformation. 739 P1091/L18 The analogy to steroids in not appropriate. If one reads the IPCC SREX response to the FAQ (is becoming more extreme, p.124) next to this paragraph, one is left with the impression that this draft is hype. 740 P1092 reference for the caption conclusions should be provided and validity assessed through traceable account (this is not commonly covered in assessments). 741 P1093/L24 “availability of calcium carbonate” does not make sense? Perhaps concentration of carbonate ion is what is meant? 742 P1095/L7 “supersaturated with calcium carbonate minerals” does not make sense. 743 P1095/L8 “concentration of these minerals” does not make sense. 744 P1095/L11 30% — shouldn’t this now be higher since CO2 has increased 40%? 745 P1095/L15 Should also mention that there are large variations in pH in ocean sediments. The 20 million only refers to inferred average ocean surface pH. 746 P1095/L23 The shell shown seems to not include the actual pteropod (only the shell). Is this all the evidence that we have (it is not convincing or particularly relevant since shells have always been dissolving on some parts of the sea floor)? 747 P1096/L1 This text does not answer the question of trust and the NCA largely does not discuss uncertainty of projections. Clearly we would not trust the models in the same way we trust those that, for example, control airplanes. 748 P1096/L14 “do a good job”? No proof provided. Projections of precipitation differ in sign between some models which is hard to describe as “good job.” 749 P1099 Should show estimates of uncertainties in projections. 750 P1100 This section seems to go further than the executive summary says we know about tipping points. It should be explained that there is not a consensus among models about major tipping points occurring this century. 751 P1108 Variability or vulnerability? This chart needs discussion if included. 752 P1109/L11 Biofuels? The land use and life cycle emissions of corn ethanol mean it cannot contribute significantly. 753 P1109 This page only describes end use and not power generation which has large scope for reducing emissions.