Children born now may live in a world where the US can only produce half as much of its key food crops
By Madison Hall
News Article: https://www.cnn.com/2025/06/18/climate/food-crops-heat-rain
Research Article: https://www.nature.com/articles/s41586-025-09085-w
Background:
As global temperatures rise, the world's ecosystems will change. The effects of climate change on resources such as water and soil will cause changes in crop production, which will vary by region [1]. Major crops that may be affected by climate change include, but are not limited to, wheat, maize, soybeans, rice, sorghum, and cassava. It is meaningful to examine how these crops will be affected by climate change because they are widely considered to be staple crops and are grown in large quantities across the globe, making up significant proportions of the calories required for a standard diet [2]. To make projections, this paper uses both a high-emissions and moderate-emissions scenario, which correspond to RCP 8.5 and 4.5, respectively. RCPs, or representative concentration pathways, are projections of radiative forcing and can act as inputs for climate modeling [3].While it is accepted that climate change threatens global food systems, the degree to which adaptations can reduce losses is generally lesser-known. However, there is some research that suggests that an adaptation method that may offset crop loss due to climate change significantly is irrigation [4]. It is also important to consider the economic conditions faced by producers, as that will affect how well they are able to adapt to the changing climate.
The authors’ main goal was to quantify crop yield loss in the future, accounting for both the effects of climate change and adaptations made as a result of climate change. First, the article offers a brief explanation of the fact that the extent to which producers will adapt to climate change has not been systematically studied, and subsequently makes the point that although it is known that climate change will affect crop yields globally, current loss projections have not been able to account for producer adaptations. Next, the study’s methods are described. To make their projections of decreased crop yields accounting for both climate change and adaptation, researchers used data on staple crops over 12,658 subnational administrative units. These units were found in 54 countries which had varied socioeconomic conditions and local climates. Also selected were weather aspects which affect biophysical processes of crops, degree of producer adaptation, local adaptation benefits versus costs, and finally, differences in access to resources.
Figure 1. Global econometric analysis of longitudinal subnational administrative data enables empirical estimation of crop-specific climate impacts that vary with local economic and environmental conditions.
The authors also describe their final model and explain that the model for each of the six crops examined in this study (including rice, sorghum, cassava, wheat, maize, and soybeans) includes several weather measurements associated with climate measurements, along with income and irrigation. Their model is nonlinear, and dependent on the factors previously mentioned. They project yield impacts due to climate change to 24,379 administrative regions across the globe through the year 2100. Additionally, they include both high and moderate emissions scenarios. The projected estimate of effect of climate change on crop yield varies in different regions, due to differences in both initial climate and changes in their climate, as well as socioeconomic conditions. From their analysis, it becomes clear that changes in temperature have the greatest impact on local crop yields across all crops. Another pattern that emerges is the result that, in equatorial regions that experience high rainfall, such as central Africa, Southeast Asia, and South America, benefits from moderate temperatures (longer growing seasons) are magnified by increasing precipitation levels.
Next, the loss in yield of each of the six staple crops which this study examines are described. Notable losses in a high-emissions scenario include a loss of 40% of maize yield in the grain belts of the US, Eastern China, Central Asia, Southern Africa, and and the Middle East, 30-40% loss of wheat yield in China, Russia, the US, and Canada by the end of this century. The figure below shows these results:
Figure 2. Projected end-of-century change in crop yields resulting from climate change, accounting for adaptation to climate and increasing incomes.
Aggregating results from different regions and accounting for costs and benefits from adaptation, the study finds the following global yield impact projections for the end of the century (2100) under both high-emissions/moderate-emissions (RCP 8.5/RCP 4.5) scenarios: −27.8%/−12.0% (P = 0.258/0.308) for maize, −6.0%/−1.1% (P = 0.477/0.475) for rice, −35.6%/−22.4% (P = 0.185/0.206) for soybean, −29.8%/−12.8% (P = 0.179/0.248) for cassava, −21.7%/−5.9% (P = 0.329/0.417) for sorghum and −28.2%/−13.5% (P = 0.038/0.058) for wheat.
Figure 3. Global impact of climate change on staple crops.
It is clear in the figure above that yields due to heat impact are pronounced and nonlinear for many crops. However, global yields were not found to be decreased the most in the world’s hottest regions, but rather, the middle 50% that experience moderate temperatures. Additionally, global yields (and subsequently, global calorie production), disproportionately affect regions of different socioeconomic statuses. Lower-income regions tend to be located in warmer climates, where higher precipitation partially mitigates the impacts of increased temperatures. This is meaningful because higher-income regions, which contain many of the world’s ‘breadbaskets,’ or regions in which large quantities of grains and other crops are produced, will be more negatively affected. Next, using the projections of crop yields above, the paper estimates that a 1℃ increase in global mean surface temperature (GMST) correlates to -121 calories per day per person in the year 2100, or approximately 4.4% of current per capita recommended consumption for every degree. Finally, the paper estimates that, in a high-emissions scenario, producer adaptation may reduce impacts on global calorie production by approximately 23% in 2050 and 34% by the end of the century. Also discussed is the social cost of carbon (SCC) (value of economic harm that results from the emission of an extra ton of carbon dioxide). Researchers calculated the SCC resulting from yield changes in global crops. To do so, they assigned average prices by country to total calorie consumption. From this analysis, the SCC ranges from $0.99/ton of CO2 to $49.48/ton of CO2.
CNN article “Children born now may live in a world where the US can only produce half as much of its key food crops” by Laura Paddison begins with a brief summary of a key finding of the research article - the conclusion that production of some crops could decrease by as much as 50% by the end of the century. Paddison then lists the crops that the study used in its analysis (maize, soybeans, rice, wheat, cassava, and sorghum), as well as the fact that the study takes into account farmers’ adaptations to climate change. After this introduction, she reviews important data from the paper, and focuses primarily on percentages of crop losses in different regions of the world. Specifically, she includes that maize, wheat, and soybean yields could decrease by as much as 40, 40, and 50 percent, respectively, in various regions across the globe. Paddison also highlights the paper’s finding that every 1℃ increase in global temperature will decrease food production by approximately 120 calories per person per day. In this section the author also includes a figure from the research paper which visually depicts the percent change in crop yield by the year 2100.
In the next section of the news article, Paddison includes various quotes, the first one being from one of the paper’s authors. In the quote, Andrew Hultgren discusses the negative effects climate change will have on corn production in the midwest region of the United States (the “corn belt”). Then, Paddison explains that crop production in lower-income countries will also be affected by climate change alongside higher-income countries such as the US. Subsequently, she includes points from individuals who were not involved in the research which highlight the importance of the study’s findings but also its limitations. Finally, Paddison ends her article by stressing the urgency of climate change as it pertains to the negative effects it may have on crop production as reported in the research paper.
However, one issue I had with the article was its title. The inclusion of ‘children born’ felt sensationalized rather than informative. Additionally, while the article did at various points about both main sources that the research article uses as farmer adaptation to climate change, which were irrigation and increased income, it did not outright list them but rather mentioned them at different points in the news article. The technique of accounting for human adaptation is an integral part of the study and the research paper’s findings, so I think it would have been more effective for the author to have explicitly described them in the beginning of the article and put a greater emphasis on them.
Citations:
[1] https://www.climatehubs.usda.gov/croplands-changing-climate
[2] https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/staple-food
[3] https://sos.noaa.gov/catalog/datasets/climate-model-temperature-change-rcp-45-2006-2100/
[4] Abramoff, R. Z., Ciais, P., Zhu, P. Hasegawa, T. Wakatsuki, H., & Makowski, D. (2023). Adaptation strategiees strongly reduce the future impacts of climate change on simulated crop yields. Earth's Future, 11, e2022EF003190. https://doi.org/10.1029/2022EF03190
Madison, thank you for your analysis and for sharing this interesting article with us.
ReplyDeleteThe news article does a good job of emphasizing that the U.S. specifically may lose its ability to produce half as much of its key food crops. However, the peer-reviewed study it references is global in scope and not specific to the U.S.
If there is an optimal temperature range for growing staple crops, climate change will likely make some regions less suitable—but wouldn’t it also make other regions more suitable? For example, rice is mentioned as a crop that may benefit from warmer temperatures.
Looking at Figure 2, which shows percentage changes ranging from -100% to +100%, does this mean that while some areas may experience losses, others could see gains? If that’s the case, why does Figure 3 show an overall steady decline in crop yields? Wouldn’t new suitable regions offset some of the losses, especially in areas that historically haven’t grown these crops?
Additionally, while climate change will inevitably impact the types of crops we’re used to growing and the regions where they’re traditionally produced, it could also create opportunities for other regions to cultivate these crops—or even encourage the adoption of alternative crops not historically grown, such as amaranth and Fonio, which are better suited to hotter climates.
Finally, at the end of your analysis, you briefly mentioned the SCC. How is that relevant in this context? Is it the same as the high- and moderate-emissions scenarios? And does the high-emissions scenario imply greater radiative forcing compared to the moderate-emissions one?
Frozan, thanks for your feedback! In regards to effects of rising temperatures, the paper does discuss the fact that the middle 50% of climates will suffer the largest yield losses, while naturally hotter climates are already more adapted to heat, and that naturally colder regions could even see benefits from warming temperatures. These potential increases in crop yields across various regions is why Figure 2 has a percentage change range of -100% to 100%. You are correct that some regions may experience increased crop yields; however, globally, total crop production will decrease. This is the reason that Figure 3, which illustrates the global, rather than regional impacts of climate change on crop yield, shows a steady decline.
DeleteYour point about cultivating different crops in response to climate change is really interesting! The paper focuses only on the six staple crops mentioned at various points in my analysis, but I would be curious as to how crop diversification could factor into projected yields if it was treated as a method of adaptation.
SCC is used in this paper to contextualize future losses in global crop yields in the frame of current climate policy. I think that the paper's authors chose to include this information as an additional way to emphasize economic consequences of climate change on crop yields, as incomes and costs of adaptation are variables used in the study's analysis. In this section, it is stated that the SCC is calculated using factors such as discounting, flexible crop switching, movement of cropped land and trade, supply and demand, etc. It is presented as a range of values. Finally, the high-emissions scenario does imply greater radiative forcing compared to the moderate-emissions scenario. In my 'background' section, I noted that the paper uses RCP values of 8.5 (high-emissions) and 4.5 (moderate-emissions) in its analyses.
Hi Madison,
ReplyDeleteI really liked your overall analysis of the news-article. I agree that the CNN piece amplified aspects of the peer-reviewed article in a way that felt somewhat sensationalized. After reading the peer-reviewed article, I also agree that the authors should've mentioned the exclusion of human innovation from their statistical model earlier on. Because human innovation is not directly included, the statistical model likely gives a more pessimistic but realistic estimate if no major breakthroughs happen.
You include Figure. 3 in your discussion. Panel b in the figure shows that crop yields don’t drop the most in the world’s hottest areas. Instead, the biggest losses are projected in places with moderate average temperatures, many of which are major food-producing regions. The authors explain this observation because hot regions have already adapted to difficult climate conditions by changing their farming practices, like using irrigation. In contrast, the authors also mention that cooler regions haven’t needed to adapt as much in the past, so they are less prepared for future warming.
Panel b shows that crop yields in hotter regions don’t decline as much with rising temperatures, likely because those areas have already adapted. If past adaptation helped reduce climate damage in these regions, could similar strategies help protect cooler, high-producing regions in the future?
Hi Gergana, I appreciate your comment! I believe that similar strategies used in already-hot regions could be useful in adaptation to increased temperatures in naturally cooler regions. I think adaptation methods such as irrigation that are widely used in areas with hot climates would be essential in decreasing yield loss, which is why it is emphasized in the paper. Additionally, another commenter approached the idea of introduction of alternative, more heat-resistant crops in response to increased temperatures. One conclusion that the article makes is that in general, poorer regions that are also located in regions with hot climates will see lower impacts in total calorie production. The paper also discusses that often, these regions rely on staple crops like cassava rather than maize or other crops more frequently grown in wealthier countries. This opens a potentially interesting discussion and alludes to the conclusion that growing more heat-resistant, 'durable' crops may also be a strategy that naturally cooler regions could adopt as temperatures rise.
DeleteHi Madison! I really enjoyed your analysis of these articles. I also thought the CNN article did an excellent job of communicating accurate and engaging information about the topic. I find this topic really interesting because climate change is often not acknowledged for having more nuanced impacts on the world aside from strictly temperature changes. Breaking down how temperature increases have a significant impact on crop yields is important for the general public to understand because climate change feels like a more personal issue, and it shows how climate change has far-reaching impacts on the global population in a number of ways. I also really appreciated the distinction between lower and higher income agricultural areas due to its high relevance to this issue. Low income areas suffer the brunt of climate change's adverse effects, but also do the majority of the labor that supports higher income regions. Focusing our efforts on protecting those regions and populations is the most important part of climate activism, and the issue of lower crop yields symbolizes this very well.
ReplyDeleteEliza, thanks for your feedback. I agree that this article was really interesting and not a topic that I usually think of first when climate change is discussed. Similarly to what you mentioned, I feel like I tend to think more about increasing temperatures and rising sea levels in regards to climate change than other effects caused by warmer temperatures. I appreciated that socioeconomic status was such a significant part of the paper's discussion because it is a really meaningful factor in how different populations are/will be affected by climate change.
DeleteHi Madison, Excellent breakdown of this dense paper. You did a great job explaining how the study quantifies the role of adaptation, which is its key innovation.
ReplyDeleteThe finding that adaptation and economic development can alleviate about a third of the damages by the end of the century is a key piece of information. It confirms that adaptation is a valuable and necessary strategy. However, it also soberingly implies that even with these adaptations, two-thirds of the damage remains. This makes me think about their Social Cost of Carbon (SCC) calculation. Since their partial SCC of up to ~$49/ton already includes the benefits of adaptation, does this suggest that the true cost of climate change on agriculture, if we failed to adapt, would be significantly higher? It really puts the economic value of investing in adaptive technologies into perspective.
Siyu, thank you for your comment! I agree that the article's findings are very sobering. As to the calculation of the Social Cost of Carbon, the paper describes that its calculations considered adaptations such as shifting of cropped areas, trade, etc. Because the SCC reported in the paper accounts for adaptation, I believe that it is reasonable to assume that the cost would increase if there were to be no adaptation.
DeleteNice job Madison. Overall I would agree with your rating of 8.5/10. I felt the news article truly captured the points the study was trying to convey. I liked your point that explicitly listing the potential solutions for the future of agriculture at the beginning of the article would have been a more effective way to emphasize a solution to the challenges that based on this article we are set to face. Understanding how farmers and governments can respond, particularly through methods like irrigation or income-based support, is essential for identifying practical solutions for the future of agriculture.
ReplyDeleteOne part that stood out to me was how these impacts are unequally distributed. It is especially interesting that many of the countries projected to suffer the worst effects are also among those most responsible for emissions. I'm also curious what your thoughts are on how we are to create pressure or consequences for governments and corporations responsible for these emissions?
Thanks for your comment, Sarea! I agree that it is interesting that the study finds that the countries which are projected to experience the worst crop yield losses are also countries that produce high emissions. I think that first of all, research like that included in this study that quantifies negative effects from climate change is important. I believe that strict emissions regulations are essential in lessening large corporations' effects on climate change and warming global temperatures. However, I am not entirely sure what to recommend as what I think could be the best method of enacting regulations such as those, especially in today's current political climate. I would argue that reporting findings such as the ones included in this study and making results widely accessible is an important first step, though.
DeleteFascinating article that you picked, Madison! I think it's so interesting that the central latitudes, although facing hotter temperatures due to proximity to the equator, are also facing increased precipitation, which could mitigate the impacts of hotter temperatures on these staple crops. Of course, it's important to consider the the increased precipitation also negatively impacting people's homes in the cases of hurricanes and similar natural disasters, but obviously that's beyond the scope of the article here. The impact on the mid-latitudes' abilities to grow staple crops, though, does make me think about the GMO crops and the copy-written seeds that certain companies made, so as to not allow farmers to replant their seeds and instead force them to buy new seeds from the company. That may further impact growing capabilities, if and when the crops are impacted by the changing climate.
ReplyDelete