Our directory of things of interest

University Directory

Eastward expansion: why the 100th meridian is on the move

American farmland (such as this one in South Dakota) could find itself being restructured as climate conditions move humid conditions more towards the east of the country American farmland (such as this one in South Dakota) could find itself being restructured as climate conditions move humid conditions more towards the east of the country
02 Jun
2018
As climate conditions at the 100th meridian, the traditional United States boundary between the humid east and the dry west, are shown to be on the move, could it mean a reshaping of America’s farmlands?

 In 1878, explorer John Wesley Powell travelled east to west across the US and noticed a change in the plants around him. Over a relatively small transect of land, prairie flowers gave way to drier shrubs, which in turn gave way to cacti. This gradual but strong transition, between the humid east and the dry west, extended in a straight line from north to south of the US, roughly following the 100th meridian. New research has now confirmed that this climate divide is gradually moving towards the east.

The divide can be seen from space, on Google Earth, and ‘is also plain to window seat passengers flying on airplanes across the continent’ say researchers from the the University of Columbia who have been looking into this territorial shift.

Though scientists largely agree that the climate divide along the 100th meridian exists, the Columbia study is the first to examine its causes. By looking at precipitation models, the team discovered the divide occurs for three reasons: the east is kept wetter by winter storms from the Atlantic and summer storms from the Gulf of Mexico that bend northeast. Meanwhile storms from the Pacific are wicked away by the Rocky Mountains, leaving the west dry.

us mapThe climate divide is readily visible on maps of the US

According to the findings, these dry conditions are moving eastwards. By analysing climate data from 1979 to 2015, the researchers found there had already been a noticeable trend eastwards of the arid climate, now putting the divide roughly at the 98th meridian. ‘There have also been contributions from declining precipitation but we think those might mostly be due to natural variability,’ says Richard Seager, lead author of the study. He believes it is rising temperatures that will increase evaporation and move the arid conditions further eastward. By linking these findings with climate change models, the team predicts that the easterly trend will continue to become more noticeable throughout the 21st century.

If the predictions become true, it could amount to big repercussions for land use along the 100th meridian. Already farming is largely dictated by the divide: moving west across it, farms become fewer and larger by land area, reflecting less available quantities of water. The majority of crops also change from moisture-loving corn, to plants that cope better with dry conditions, such as wheat. The researchers predict that these characteristics will need to be incorporated into the land around the 98th meridian in order to handle the warming conditions to come, potentially redrawing the agricultural maps of North and South Dakota, Nebraska, Kansas, Oklahoma and Texas.

This was published in the June 2018 edition of Geographical magazine

geo line break v3

Free eBooks - Geographical Newsletter

Get the best of Geographical delivered straight to your inbox by signing up to our weekly newsletter and get a free collection of eBooks!

geo line break v3

Related items

Subscribe and Save!

geo line break v3

Free eBooks - Geographical Newsletter

Sign up for our weekly newsletter today and get a FREE eBook collection!

geo line break v3

University of Winchester

geo line break v3

EDUCATION PARTNERS

Aberystwyth University University of Greenwich The University of Derby

TRAVEL PARTNERS

Ponant

Silversea

Travel the Unknown

NEVER MISS A STORY - Follow Geographical on Social

Want to stay up to date with breaking Geographical stories? Join the thousands following us on Twitter, Facebook and Instagram and stay informed about the world.

More articles in NATURE...

Geophoto

Mountains provide a dramatic sight at the best of times,…

Wildlife

A surge in reports of dead hares has resulted in…

Oceans

Four scientists have banded together to make the case against the farming of octopuses, arguing…

Climate

As planetary oil consumption hits the 100-million-barrel mark Marco Magrini…

Oceans

A ship that ran aground early in February has been…

Wildlife

Two whale populations on either side of the African continent…

Geophoto

March traditionally heralds the beginning of spring, a time of…

Wildlife

An innovative project to utilise Laos’ elephant experts in service…

Polar

Despite common belief that Antarctica is vastly uninhabited, humans are…

Wildlife

Javan rhinos survived the recent Krakatoa tsunami, but the species…

Energy

As the world turns away from fossil fuels, one question…

Geophoto

The winners of the Outdoor Photographer of the Year 2018…

Climate

New legislation in Florida aims to solve various environmental issues,…

Polar

The world’s magnetic model is getting an early update, as…

Climate

Marco Magrini looks at the financial pressures spilling out into the…

Geophoto

Few sights are more dramatic than a star-filled sky at…

Polar

A region of Antarctica previously known for relative stability is…

Tectonics

Everything we thought we knew about eruptions could be wrong

Oceans

Sea levels are rising across the globe, but along the…

Polar

Seismometers buried in the Ross Ice Shelf have revealed that…