The United States Global Change Research Program’s (USGCRP) National Climate Assessment (NCA) could serve as a crucial resource for objectively and comprehensively understanding the impacts of climate change. However, in its current form, the framing, methodology, and communication strategies employed by the NCA make it far less useful than its potential. It is currently (correctly) perceived as a political document, and thus, the Trump administration is likely to either overhaul or scrap it. Ideally, the NCA could be transformed into a document recognized as valuable by both sides of the political aisle instead of merely reflecting the perspective of the party in office at the time of its creation. Below are some brief recommendations for producing such a document. It would be seen as less political, more resilient to administrative changes, and provide clearer, more balanced, and more useful information for decision-makers and the public.

1. A Broader Framing of Research Questions

Seeing Climate Change in Terms of Both Threats and Opportunities

The current NCA presents climate change almost as if it is categorically detrimental, but there is no physical law dictating that a warmer climate and elevated CO₂ levels are exclusively harmful. To take just one example, higher temperatures and increased CO₂ may pose threats to U.S. corn yields, but they can also create opportunities for boosting U.S. wheat yields. Similarly, warming will increase adverse health outcomes due to hot temperatures but decrease adverse health outcomes due to cold temperatures. An even-handed and useful assessment should evaluate the full spectrum of impacts on both the positive and negative sides of the ledger without being overly focused on seeking out and highlighting negative impacts.

Total Risk vs. Additional Risk

The current NCA tends to focus narrowly on “additional climate risk,” which can leave false impressions by not putting the impact of climate change in the context of other relevant causal factors. Using a “total risk” framework, as recommended by former NCA and IPCC author Brian O’Neill, solves this problem and avoids the confusing rhetorical ambiguity where the direction of a trend is conflated with the direction of an impact. Placing climate impacts in the context of other relevant factors—such as technological innovation, economic and social changes—enables decision-makers to see a more complete view of the state of the problem.

2. Accounting for Exposure and Vulnerability

Going Beyond Physical Hazards

When it comes to understanding the economic and human impacts of extreme weather, the NCA should emphasize that disaster risk results from the interplay of three key elements:

• Physical Hazard: The frequency/intensity of physical weather and climate events (e.g., wildfires, extreme temperatures, precipitation events, droughts, hurricanes)
• Exposure: The amount of people and assets in harm’s way.
• Vulnerability: The susceptibility of people and assets to damage.

Previous NCA reports centered rising disaster costs with the implication that this was almost entirely due to increases in hazard frequency and intensity. However, increases in exposure likely dominate rising disaster costs, and thus, a useful report would acknowledge this. A NCA that systematically examines changes in exposure and vulnerability, in addition to changes in hazards, would provide a more accurate representation of total risk and thus provide more useful and actionable information to policymakers.

Acknowledging Adaptation and Resilience

Humanity has had tremendous success adapting to our often hostile climate but is nowhere near sufficiently adapted to its hazards (if it were, hurricanes, for example, would do no damage). Given this, the NCA should consider identifying sectors of society that would disproportionately benefit from increased resilience independent of the degree to which relevant hazards are changing. Enhanced infrastructure, early warning systems, and better urban planning can mitigate damage regardless of whether or how hurricanes and other hazards are increasing in frequency or strength. Identifying these gaps—sectors that would benefit the most from adaptation efforts—should be a priority within the NCA.

3. Synthesizing Knowledge with Systematic Reviews

Using Formal Guidelines for Literature Assessment

Assessment reports should attempt to avoid approaches where the author's subjective judgment, along with their social/professional affiliations, have a major influence on the narrative being presented and the research that is cited or promoted. Implementing established review frameworks—like the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)—can bring rigor and transparency to the research selection process by explicitly cataloging search terms and criteria for inclusion/exclusion (credit to Roger Pielke for this suggestion). Subsequent discussions that employ subjective analysis and value judgments regarding studies can follow afterward.

Systematically Delineate Between Different Kinds of Knowledge

Every section should conduct a systematic review of 1) observations/trends, 2) theoretical frameworks, and 3) modeling, accompanied by a thorough cataloging of the sensitivity of results to various observational datasets and models, as well as a discussion of competing theoretical explanations. The IPCC Working Group 1 Chapter 11 follows a format similar to this.

Addressing Publication Bias

The assessment should explicitly address potential selection effects within the published literature, particularly focusing on the concept of Publication Bias (commonly referred to as the file drawer effect). It is essential to evaluate whether the published literature accurately represents an unbiased sample of our comprehensive understanding of each topic. Should it be determined that the published literature is likely biased in a particular direction, the report should consider conducting fundamental original analyses aimed at uncovering null results or results that may not have been organically revealed through the research community’s inherent selection choices.

4. Improving Communication Style

Description Over Persuasion

An assessment aimed at informing should focus on presenting high-level observational metrics with as little pre-processing as possible before moving on to potential climate impacts. This style is exemplified by the Bulletin of the American Meteorological Society’s (BAMS) “State of the Climate” reports. Thus, prior to a discussion of the climate impacts on crop yields or health outcomes, changes in raw yields and health outcomes over the past should be shown.

Moving Away from Headline-Style Key Messages

The current “Key Messages” in the NCA often read more like calls to action than neutral statements of scientific findings—for example, “Climate Change Is Harming Human Health” “Systemic Racism and Discrimination Exacerbate Climate Impacts on Human Health”, “Climate Change Affects the Economy Directly,” “Self-Determination Is Key to Indigenous Peoples’ Resilience to Climate Change.” These do not necessarily provide the quantitative or comparative data that decision-makers need to understand the magnitude of the impact of climate change on various sectors of society. Replacing persuasive headings with neutral, data-focused summaries would enhance the report’s credibility and utility.

Reconsidering Frivolous Sections

An objective scientific report should focus on delivering robust and actionable information, not on promoting activism. For example, the current report includes a “ClimateXArt” section on “the understanding that, together, art and science move people to greater understanding and action.” An objective scientific report intended to inform rather than persuade would not include such a section.

5. Conclusion

The NCA can reform its current image as a political tool by presenting the total picture—considering both threats and opportunities, incorporating exposure and vulnerability into disaster cost analyses, leveraging systematic review methods, and communicating findings in an objective, data-centric manner. These reforms would not only make the report more useful but also allow it to be more robust to pendulum swings between administrations.