The Fifth National Climate Assessment (NCA5) is the U.S. Government’s preeminent report on climate change impacts, risks, and responses. It is a congressionally mandated interagency effort that provides the scientific foundation to support informed decision-making across the U.S. Released on November 14, 2023, it was assembled by teams of researchers from a range of climate change specialties and represents a synthesis of current research. As those following developments in agriculture know, climate impacts have become increasingly apparent since the fourth assessment was published in 2018.

This summary by Cathy Day, Ph.D., prioritizes aspects of the report most relevant to agriculture, presenting a national overview. Specific findings for the Southeast U.S. and Caribbean Territories have been highlighted here to reflect RAFI’s service area. This article was excerpted and reprinted with permission from the author and the National Sustainable Agriculture Coalition (NSAC).

While the NCA5 covers a lot of ground in several chapters, the primary message is that the risks to agricultural production are rising and will continue to rise as a result of climate change. The authors rank this evaluation as “very likely” with “very high confidence” of its accuracy. Despite the challenges ahead, there are substantial reasons for optimism, both in the proposed routes to emissions reductions and in the transformation toward increasingly robust farming systems.

The Physical Science

Some of the clearest reasons for concern about impacts on agriculture are laid out in the chapter on water. For example, increasing aridity in the Southwest and increasingly wet conditions throughout the northeast regions of the country — from the Midwest through New England — are likely to challenge crop and livestock production. Drought and torrential rain will frequently reduce productivity in all regions. Despite wetter conditions in parts of the country, researchers expect higher temperatures to reduce overall soil moisture in most regions. Climatic water deficit, a measure of the shortfall of water available for plants to meet their needs, gives an overall sense of the country’s water outlook. Particularly acute deficits are expected in much of the country west of the 100th meridian (a rough dividing line between the more humid eastern part of the country and the arid western part — from North Dakota through Texas). Along with these changes, USDA plant hardiness zones will continue to shift as temperatures continue to rise. Species and varieties that once functioned well in a given area may no longer be adapted to the warmer temperatures they experience as the climate changes.

The agriculture chapter notes that all dimensions of food security will be affected by climate change and that crop insurance costs have already risen in response to increased losses. Total Factor Productivity (TFP) is a measure used in economics to gauge the efficiency and effectiveness with which all inputs are turned into outputs in the production process. In agriculture, despite a steady growth since 1948 (primarily because of technological changes), the climate crisis has already dampened TFP growth, and agricultural TFP is expected to decline to pre-1980 levels by 2050 unless adaptation measures adequately respond. Because of increased crop specialization in the Midwest, TFP is more sensitive to increasing summer temperatures and moisture deficits. In short, much of the current system is more susceptible to climate impacts because of current monocultural practices.

Focus on Solutions

Although there are clear negative impacts for agriculture, the agriculture chapter effectively lays out the ways in which agriculture can respond constructively to increasing challenges. The authors identify the continued risks presented by “excessive tillage, overgrazing, and overreliance on agrochemicals.” In response, the chapter centers agroecological solutions like enhanced soil health and diversified landscapes. This focus represents a noticeable shift from the Fourth Assessment, where “climate-smart” solutions focused on improved technologies (e.g., high-efficiency irrigation and genetic modification) rather than systems approaches.

However, solutions to livestock methane focus on feed supplements and energy capture from liquid manure systems, rather than grazing systems. The authors do not discuss the advantages of highly managed pasture carbon sequestration outweighing the emissions of associated livestock. So, unfortunately, the increased systems approach of the chapter is not applied across all agricultural issues. On the other hand, the chapter’s assessment of alternative plant proteins is more measured, noting their potential to reduce greenhouse gas emissions but also identifying the clear downsides in terms of increased needs for infrastructure and energy.

Strong Environmental Justice Discussions

Another way in which NCA5 represents an advancement upon NCA4 is its strong discussions around environmental justice. The agriculture chapter’s Key Message 2, “Climate Change Disrupts Our Food System in Uneven Ways,” puts worsening heat stress among farm workers front and center. The authors also note ongoing and increasing “disruptions to the ability of subsistence-based peoples to access food through hunting, fishing, and foraging.” In addition to laying out how social and economic factors make some segments of society more vulnerable, the chapter also demonstrates how many of the same populations are developing their own solutions.

Beyond the agriculture chapter, each of the regional chapters also puts a spotlight on both the inequities built into U.S. systems and on how overburdened communities are identifying and building out unique solutions.

Southeast

The challenges highlighted for the Southeast are sea level rise and consequent saltwater intrusion (a notable issue in states like North Carolina), as well as the Southeast’s increasing droughts. Further, the authors note the health and livelihood impacts on outdoor workers because of rising heat. The Southeast is one of the regions most affected by heat waves. Hurricanes also present unique challenges, as seen with Hurricane Florence, which resulted in heavy flooding that left parts of the region covered in hog waste. The disproportionate impact of the climate crisis on BIPOC communities and on lower-resourced small-acreage farms is among the issues the chapter identifies as important for the Southeast to resolve.

Caribbean

The Caribbean chapter focuses on the U.S., including Puerto Rico and the U.S. Virgin Islands (USVI). Daily average temperatures in the region are increasing. Puerto Rico has no clear trend in rainfall except for an overall annual reduction by the end of this century and more drought. Other risks include increasing tropical cyclones and sea level rise.

Unfortunately, the exclusion of Puerto Rico and the Virgin Islands from many data collection processes limits the ability of decision-makers in the region to understand and adapt to climate change. Nonetheless, more extreme weather and the region’s high dependence on imported food (80% for Puerto Rico, 90% for the USVI) will leave the area increasingly vulnerable. High crop losses from recent hurricanes, including Maria in 2017, resulted not only from direct impacts from the storms but also from related energy, telecommunications, and water supply outages along with damage to roads and irrigation systems.

Higher temperatures can stress both crops and livestock. In fact, livestock are more vulnerable than they might be because many breeds have been imported from the U.S. mainland and are more adapted to mainland conditions.

Crop insurance, such as that provided by the Puerto Rico Crop Insurance Corporation (PRCIC), offers protection. However, 98% of PRCIC payouts in the last decade were from hurricanes, highlighting the steep adaptive needs presented by storms. In addition, the program does not cover the growing challenge of drought conditions.

Conclusion

The climate challenges that U.S. agriculture faces are steep and are expected to rise if emissions continue their current trajectory. However, communities around the country are recognizing their own role in reducing emissions and adapting to changes. As recognition of the value of Indigenous, Tribal, and other traditional knowledge systems improves, and as respect for data and decision sovereignty of those groups increases, new solutions may continue to emerge into the larger consciousness that may help with many of the challenges of agriculture.

Adaptation and community co-production of knowledge are important and must be valued. Such work will provide improved food security and livelihood stability in the future. However, the most important change will continue to be the reduction of greenhouse gas emissions. Agriculture, along with dozens of other forms of work, must continue to push hard to reduce its nitrous oxide, methane, and carbon dioxide emissions through equitable means that provide the best possible ecosystem and community outcomes across the country.

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Dr. Cathy Day is a consultant on climate change and agricultural policy based in Albuquerque, NM.