Border to arid western climate creeps closer to Iowa


1600px-Map_of_Great_Plains
The 100th Meridian, located at 100 degrees west, is shown dividing the United States’ Great Plains. This longitude line has long been considered the border between the arid west and humid east (from Wikimedia Commons).

Julia Poska | August 30, 2018

The divide between America’s dry west and humid east appears to have shifted two degrees east since the 1970’s, according to recent research from Columbia University.

Topography and atmospheric circulation from both coasts create a pattern of increasing aridity from east to west. The 100th meridian, which splits the Dakotas in half and continues south through Texas and into western Mexico, historically separated the United States’ arid and humid climate zones.

The new study, published in the journal Earth Interactions, places the wet and dry dividing line closer to 98 degrees west today. Researcher Richard Seager attributed this in part to rising temperatures in a National Public Radio interview.

The shifting climate has had major implications farms in between the 100th and 98th meridians. Corn requires warmth and humidity, while wheat can grow in more arid conditions, but both crops have suffered where the soil has dried.

Iowa’s westernmost point sits at about 96 degrees. If the western divide were to bring dry conditions another two degrees east, the results would be devastating for Iowa corn growers.

Climate projections for Iowa do anticipate further warming, but they also predict increased humidity rather than aridity (see the 2017 Iowa Climate Statement). Though Iowa is unlikely to dry out anytime soon,  climate change will nonetheless create other serious challenges for agriculture statewide.

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