Global Warming

The arid US midwest just crept 140 miles east thanks to climate change

There’s a line that stretches down North America, singeing into the continent a border that separates an arid west from a humid east. And it’s on the move.

Called “the 100th Meridian,” the line slices through Canada, the Dakotas, Nebraska, Kansas, Oklahoma, Texas, and eastern Mexico. It exists because the Rocky Mountain range blocks moisture that would sweep into the Great Plains from the Pacific Ocean, while storms in the Atlantic Ocean push moisture into the US midwest, bumping against more moisture that barrels north and slightly east from the Gulf of Mexico during the summer.

Drawing on climate models, regional vegetation data, US Department of Agriculture data, land model simulations, and weather station data, Seager was able to confirm in a recent study (pdf) that the 100th Meridian is more or less as Powell predicted. Except, as he shows in an accompanying study, by now the line has shifted eastward 140 miles.

The 100th Meridian’s eastward march will eventually force changes to the US economy. There will need to be a farm economy adjustment to this because of the environmental changes, say the researchers. The places over the western parts of the high plains will become more arid.