Shifts in Crop and Grassland Incidence in the US and Canada: What Have We Seen and What May Be Driving the Movement
This paper documents a significant reshaping of North American agriculture from the late 1970s to the early 2020s, characterized by the northward and westward expansion of crops into Canada driven by climate change and policy factors like the US Renewable Fuel Standard, while warm-season crops retreated from the US Southeast due to rising heat and declining precipitation.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
The land that feeds us is not static. For centuries, farmers have planted seeds in the same valleys and pastures, relying on the predictable rhythm of seasons to grow food and feed livestock. But the climate that shaped these agricultural patterns is changing. As winters warm and summers grow hotter, the places where crops can thrive are shifting. This is not just a matter of weather; it is a fundamental rearrangement of where food comes from. When a region becomes too hot for corn or too dry for wheat, farmers must adapt, often by moving their operations to new areas or switching to different crops that can survive the new conditions. Understanding these movements is vital because the map of where our food is grown determines the stability of our food supply, the health of our ecosystems, and the economic future of rural communities.
A team of researchers from Texas A&M University has mapped these changes across the United States and Canada, looking at how the locations of ten major crops and two types of grassland have moved over the last forty years. By comparing data from the late 1970s with data from the early 2020s, they traced the journey of crops like corn, soybeans, wheat, and cotton, as well as the land used for grazing animals and hay. Their work reveals a clear, continent-wide reshaping of agriculture driven by a combination of a warming climate and shifting human demands.
The most striking pattern is a general drift toward the north and west. Crops that can tolerate cooler temperatures, such as canola, oats, barley, and spring wheat, have moved significantly into Canada. In the Canadian provinces of Alberta and Manitoba, these crops are now growing in areas that were once too cold for them. This shift is consistent with the warming of winters and the lengthening of the growing season in northwestern Canada, which has opened up new land for farming. At the same time, warm-season crops like corn and soybeans have also pushed northward, expanding into the Dakotas, Minnesota, and southern Ontario. However, this northward expansion has come at a cost to the south. In the United States, particularly in the Southeast, the area dedicated to corn and soybeans has shrunk. These grains are retreating from regions that are becoming hotter and drier, making it harder to grow them without excessive irrigation.
Not all crops are moving in the same direction. Cotton, which thrives in heat, has moved south and east, taking over land in Alabama, Georgia, and the Carolinas that was previously used for grains. This shift suggests that as the climate warms, heat-tolerant crops are replacing those that struggle in high temperatures. Similarly, the land used for grazing livestock and growing hay has seen its own changes. Pastureland has declined in the hot, dry regions of California and Arizona but has expanded in the cooler, wetter areas of British Columbia and northern Alberta. The movement of hay production is more complex, shifting southwest in some areas and northeast in others, reflecting a mix of climate factors and changes in farming technology.
While the changing climate is a major force behind these shifts, it is not the only one. The researchers found that government policies have played a powerful role, particularly in the United States. A law known as the Renewable Fuel Standard, which encourages the use of biofuels, has driven a massive increase in the planting of corn and soybeans. This policy demand pushed farmers to plant these crops even in areas where the climate is becoming less ideal, such as the northern Great Plains. In Canada, a similar push for biofuel production helped drive a huge expansion in canola farming. The study shows that where crops are expanding, they are generally moving into areas where the land is still productive. In many cases, the new farming regions in Canada are producing yields that are just as good as, or better than, the traditional farming areas in the United States.
The researchers also looked at what happens when you only look at one country. If you were to study only the United States, you would see a story of retreat: corn and soybeans leaving the south, and a general contraction of grain farming. You would miss the fact that these crops are simply moving across the border into Canada, where they are growing successfully. This highlights the importance of looking at North America as a single, connected system. The food supply is not disappearing; it is relocating. The study concludes that the map of North American agriculture is being redrawn by two main forces: the physical changes in our climate and the economic demands of our energy and food policies. As these forces continue to evolve, the places where we grow our food will continue to change, requiring farmers and policymakers to adapt to a new reality.
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