A historic climate boundary which marks the division between the humid eastern region of North America and the more arid western region has deviated 140 miles to the east of its original location — thanks to climate change. In a study recently published in Earth Interactions, scientists identified three factors that contribute to the formation of the visible division between North American climatic zones: the Rocky Mountains’ ability to disrupt moisture from reaching inland, Atlantic winter storms and summertime humidity that rises northeast from the Gulf of Mexico.
In the recent study, lead author and climate scientist Richard Seager of Columbia University sought to explore the boundary — and its history — as a prominent example of “psychogeography,” or the relationship between environmental conditions and human decision making. The climate boundary line that runs along the 100th meridian west was first marked in the late 19th century by geologist and explorer John Wesley Powell. “Powell talked eloquently about the 100th meridian, and this concept of a boundary line has stayed with us down to the current day,” Seager said in a statement. “We wanted to ask whether there really is such a divide, and whether it’s influenced human settlement.”
The 100th meridian climate boundary has affected historic development in the United States. Eastern lands have greater population density and infrastructure, and agriculture is dominated by corn, a moisture-loving plant. To the west of the divide, agriculture is dependent on larger farms with crops — such as wheat — that flourish in arid regions, and urban development is generally more scarce.
As climate change affects the historic rainfall and temperature trends of the region, the study predicts that human development will also adapt, with eastern farms adopting characteristics of those historically found west of the boundary line. “Unless farmers turn to irrigation or otherwise adapt, they will have to turn from corn to wheat or some other more suitable crop,” said Columbia University in a statement. “Large expanses of cropland may fail altogether, and have to be converted to western-style grazing range. Water supplies could become a problem for urban areas.”