Climate Boundary Shifting East Due to Global Warming

The 100th meridian west (solid line) has long been considered the divide between the relatively moist eastern U.S., and the more arid West. Climate change may already have started shifting the divide eastward (dotted line). ( Columbia University )

Agriculture on the Great Plains in the coming decades may be adversely affected by a shifting of the climate boundary observed along the 100th meridian due to global warming. That’s the conclusion of new research published under lead author Richard Seager, a climate scientist at Columbia University.

The climate boundary that runs longitudinally along the 100th meridian through North America visibly separates the humid eastern part of the continent from the more arid western plains. Geologist and explorers observed the climate boundary nearly 150 years ago, and now Seager says that boundary may be shifting as much as 140 miles eastward.

In a statement, the researchers say the climate boundary is reflected by population and agriculture on opposite sides. Studying rainfall and temperature data since 1980, Seager and his colleagues found this climatic boundary has already shifted east about 140 miles so that it now sits closer to the 98th meridian. And it will continue to move east as warming global temperatures increase evaporation from the soil and change precipitation patterns.

The researchers believe the eastward movement of the climate boundary will almost certainly continue in the coming decades, expanding the arid climate of the western plains into what we call the Midwest. The implications for farming and other pursuits could be huge.

According to the press release by Columbia University’s Earth Institute, “Seager predicts that as drying progresses, farms further and further east will have to consolidate and become larger in order to remain viable. Unless farmers turn to irrigation or otherwise adapt, they will have to turn from corn to wheat or some other more suitable crop. 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.”