The 100th Meridian, Where the Great Plains Begin, May Be Shifting
Warming Climate May Be Moving Western Aridity Eastward
In 1878, American geologist and explorer John Wesley Powell drew an invisible line in the dirt—a long line. It was the 100th meridian west, the longitude he identified as the boundary between the humid eastern United States and the arid Western plains. Running south to north, the meridian cuts through eastern Mexico, Texas, Oklahoma, Kansas, Nebraska, the Dakotas, and the Canadian province of Manitoba on its way to the pole.
Powell, best known for exploring the Grand Canyon and other Western places, was wary of settlement in that often harsh region, and tried convincing Congress to lay out water and land-management districts crossing state lines to deal with environmental constraints. Western politicians hated the idea, fearing it might limit development and their own power, and it never went anywhere. It was not the first time politicians would ignore the advice of scientists.
Now, 140 years later, in two just-published papers, scientists examine how the 100th meridian has played out in history, and what the future may hold. They confirm that the divide has turned out to be real, as reflected by population and agriculture on opposite sides. They say also that the line appears to be slowly moving eastward, due to climate change, and that it will probably continue shifting in coming decades, expanding the arid climate of the western plains into what we think of as the Midwest. The implications for farming and other pursuits could be huge.
One can literally step over the meridian line, but the boundary it represents is more gradual. In 1890, Powell wrote, “Passing from east to west across this belt a wonderful transformation is observed. On the east a luxuriant growth of grass is seen, and the gaudy flowers of the order Compositae make the prairie landscape beautiful. Passing westward, species after species of luxuriant grass and brilliant flowering plants disappear; the ground gradually becomes naked, with bunch grasses here and there; now and then a thorny cactus is seen, and the yucca plant thrusts out its sharp bayonets.” Today, his description would only partly apply; the “luxuriant grass” of the eastern prairie was long ago plowed under for corn and other crops, leaving only scraps of original landscape. The scrubby growth of the far west remains more intact.
“Powell talked eloquently about the 100th meridian, and this concept of a boundary line has stayed with us down to the current day,” said Richard Seager, a climate scientist at Columbia University’s Lamont-Doherty Earth Observatory and lead author of both papers. “We wanted to ask whether there really is such a divide, and whether it’s influenced human settlement.” He calls the studies an example of “psychogeography”—the examination of how environment affects human decisions. They appear in the current edition of the journal Earth Interactions.
While the climate divide is not a literal line, it is about the closest thing around–arid on one side, relatively wet on the other. Powell noted correctly that the western plains are dry in part because they lie in the rain shadow of the Rocky Mountains, which rake off almost all the moisture blowing in from the Pacific Ocean. Seager’s team identifies two other factors. In winter, Atlantic storms bring plenty of moisture into the eastern plains and Southeast, but the storms don’t make it far enough to moisten the western plains. In summer, moisture from the Gulf of Mexico moves northward, but that also curves eastward, again providing the East with rain, while the West gets cheated. Seager says there is only one other such major straight-line climate divide on the global map: the one separating the Sahara Desert from the rest of Africa, also due to cutoffs of prevailing oceanic winds.
In the United States, the effects show up in obvious ways. To the west, population density drops sharply. There are fewer homes, commercial facilities and roads. Farms are fewer, but bigger, reflecting the economics of less water and lower productivity. To the east, 70 percent of the crop is moisture-loving corn; to the west, aridity-resistant wheat is dominant.
Now, warming climate appears to be pushing the divide east. In the northern plains, rainfall has not changed much, but temperatures are going up, increasing evaporation from the soil. Further south, shifts in wind patterns are causing less rain to fall. Either way, this is pushing aridity eastward. As a result, data collected since about 1980 suggests that the statistical divide between humid and arid has now shifted closer to the 98th meridian, some 140 miles east. (In Texas, this would move it roughly from Abilene to Fort Worth.) Seager says year-to-year weather variations may blur the data, and so far the changes are still too small and gradual to yet affect land use over wide areas. But he is confident that aridity will perceptibly move eastward during the 21st century, and eventually effect large-scale changes.
Seager predicts that farms further and further east will have to consolidate and become larger in order to remain viable. And unless farmers turn to irrigation or otherwise adapt, they will have to switch 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 also become a problem for urban areas.
Some historians say it could be argued that the meridian influenced even wider historical trends–everything from the end of slavery (plantations could not expand past the line, weakening the South) to the development of modern firearms (settlers’ single-shot muskets couldn’t compete with native peoples’ rapid-fire arrow attacks, until the settlers became the first, best customers for new Colt repeating revolvers and rifles). The meridian itself is still registered in popular imagination: among them, historical roadside signs, books such Wallace Stegner’s “Beyond the Hundredth Meridian”, and the Canadian rock hit “At the Hundredth Meridian.” “It’s a reminder that climate really matters, then as it does today,” said Seager.
Sooo…an imaginary line invented by Man is moving due to the weather. How does that work, exactly?
Clearly, the ‘bad weather is caused by humans’ Global Alarmist crowd doesn’t think much of the intelligence of the rest of us.
As for the shifting that the plains may be doing, so what? The Sahara has been moving throughout its history.
Impact farming? Really? I doubt the situation will change THAT drastically or rapidly. By the time it actually would make any REAL difference to farms, the farmers will have had plenty of time to adjust. On top of that, no farmer alive today will have to worry about it which is what makes this such a silly story to begin with. Not a lot they could do in the first place. We can also be 100% confident that people driving cars & flying planes has nothing whatsoever to do with it.
I own farmland east of the 100 meridian but west of the 98 meridian so this article has impact on my financial well-being. So there is no “so what” for me. I am also a scientist who builds and uses models to study potential impacts. This study is rigorously and for the most part correctly done. The limitation is that they have not considered the role of technology in changing farm sizes throughout the U.S.
Hello Numeosium! Would you mind shooting me an email at firstname.lastname@example.org? I’m working on a follow-up story here, and would love to chat with some landowners within these boundaries. Thanks!
You should come talk to actual farmers in Texas who are being impacted _today_ Most of them will tell you they don’t believe in “global warming” as a thing or is man made, but they know damn well the weather is changing year over year because it is affecting their pocket books today.
Lets see, When the federal goverment put warning labels on packs of cigarets, it was considered alarmist. Ohh and all those smokers who did not heed the warning? they like my uncle, my step dad, my former employer died from DENIAL. When the CDC adversied warning to wear a mask and wash hands, the men who denied it …are most likely dead. In both cases, Science was the tool to determine the consequence not not changing lifestyle to head the warning that they will die. Now, Earth has gone though at least five mass extinctions. Several were caused by massive injections of co2 from the burning of Coal, oil and natural gas. Did this FUCKING moron EVER consider whrere did Coal and Oil and Natrual gas come from? yes, it came from Plant life that was SUCKING up excess co2 and store it under ground so that life on earth would become habitable. Before plant life ever existed on earth, the planet was uninhabitable. global tempatures were from 300-400F. The first plant life was Cynobacteria and it helped to flood earth with at least part of the oxygen it needed. New plant life flooded earth and sucked up all that excess co2, the earths temperature plummeted from 30-400F to 59F before the start of the industrial revolution. Scientist went on top of of the Antarctic Ice sheet and drilled down 2 miles or 10, 560 feet to extract that ice and analys its ancient atmphere. they recovered 798,000 years of atmpheric air. They did samples testing of co2 for every period in that life span and found that co2 levels were stable from 798,000 year up until 1760 or the start of the industrial revolution. then after 1760, co2 levels kept climging with the global population. Good luck sirving ever increasing fire storms and floods and food scarcity and the future housing crisis. Its going to be a real killer for the planet
To promote future study have you any info as to where, lets call it the arid line, manifested it self in say 1828, 1778, 1728 and so on. Charts need to be drawn up on the speed of progression so a logical causation can be named. Also unless it’s an optical oddity it appears the arid line is slightly narrower at the north. Can/do we attribute this and possibly the whole theory/compulsion to climate diversion to say, ummm, a slight axial shift in earth due to a percieved magnetic pole flip that quite possibly is in the early stages of occuring and not to other issues that political forces wish to be the source.
As far as the aridity appearing narrower in North Dakota. I believe that’s due to season weather pattern. Artic fronts tend to blast down from Canada toward the SE across Minnesota, Iowa, and the Great Lakes.
I’m a KS native…I actually live literally on top of the 98th Merifian. Living in Iowa I noticed we had bi-annual shifts in weather direction. During the summer our weather would come from a W or SW direction. It would shift to the NW during the winter months. Kansas, for it’s part faces a straight westerly impact generally…even though its smack dab in the place for severe sudden weather…theres little rain involved in that.
I know that we don’t get the snow we did when I was a boy 30-40 years ago….and certainly not that of my parents in the 1950s.
Smaller farms came with the land grants in the 1830’s, and therefore stay to this day. The land grabs of the westward expansion allowed sections to be held, not acres. The larger farms came with the government grants originally- not the lack of water.
“no farmer alive today will have to worry about it which is what makes this such a silly story to begin with”
Yeah, heaven forbid a farmer alive today might worry about what their grandchildren will have to deal with!
I’m a 43 year old Kansas plainsman. I think older generations have given up on the notion that there will be land left for their grandchildren. Their CHILDREN no longer farm. The 1980s killed this region. It probably never truly recovered from the Dust Bowl.
Is there a map that continues on to Canada? Us up here would be very interested to know how we will be drying out.
Mike, As the story states, the line runs up through Manitoba. From there, into the Northwest Territories and Nunavut. Manitoba and other southerly provinces of course have the same Great Plains as the US. You guys even have the best song about it: “The 100th Meridian” by the great Ontario band The Tragically Hip.
I’d think your winter snow cover would help retain moisture. We don’t have that in Kansas. That stops in Nebraska for sure…perhaps even S Dakota. It’s brown winter here.
So how does this claim corroborate an earlier document at–https://nca2014.globalchange.gov/report/our-changing-climate/precipitation-change that show precipitation increases likely for the area and recent temperature and rainfall changes for Northwestern corn belt. I suspect the argument will be that the evapotranspiration in summer will be much higher, but recent weather changes since 1970s in this area have been to the contrary (fewer high summer day temps, mostly higher night time lows). From the mid-50 through the mid70s, Northwest Iowa and Eastern South Dakota, SW Minnesota would see significant crop reduction due to weather about once every 5 years. Many parts of Northwest Iowa haven’t had significant crop yield reduction because of weather since late 70s. If anything the corn growing region has significantly moved west in the last 4-decades. Modern technology? CO2 plant water eficiency?
Great article and an astute summary of a changing climate dynamic ! If only our nation had paid more attention to Powell’s observations and instituted federal programs to conserve water! Maybe the tragedy of the dust bowl would have been lessened !!!! YES – climate matters tremendously in how and whether life can adapt, including us. WE better wise up to the reality of climate changes.
The dust bowl was allowing open tiled plains ground go be subjected to plains winds. If we tilled like that now…itd do it all over again. We STILL get dust storms with open soil..especially as late winter rolls around. Cover crops helped immensely.
I am not sure where new boundary is but the 100th meridian is an absolute based on the angular distance from the prime meridian. The science of climate change is under attack by those who have a vested interest in preserving the status quo that got us where we are. What is more correct to say is the boundary is is moving east of the historical value which was the 100th meridian.
I live exactly on top of the 98th meridian. I’d have placed the line where the Flint Hills start at the East. This is basically Topeka.
Since the 100th meridian is a man-invented line, like state borders, it does not move because of climate change.
The southward expansion of the Sahara is more likely to be due to grazing practices of domesticated animals. The Gobi, on the other hand, is due to the rain shadow caused by the recent uplift of the Himalayas between the 4th and 14th centuries. At the time of Gengkis Khan, the Gobi was a grassland/great plain/veldt but was already drying. Typically, a negative change in resources leads to empire building.
It makes sense that warmer temperatures would contribute to more rapid evaporation thus encouraging the aridity moving eastward. I suggest that the continuing uplift of the Pacific coastal ranges may also be playing a part.
it’s not climate change that is the problem, it is the mismanagement of the Earth and the ever-present and 100 + years of monoculture. When you keep taking from the land or in this sense, land rape, there’s no question that adverse change is going to occur. We have seen this time and again and because of the greed, ignorance, and stupidity of the powers-that-be it will continue, until they’re brought down as part of those ruining the Earth as stated in Revelation.
Who would have ever thought “Urban Rooftop Garden’s” would ever become so important in feeding mankind. Seven plus billion people require a lot of wheat and rice. Scary thought no room for garden greens or veggies.
Climate change is BS. This change in the environment of this area has everything to do with man’s inept and destructive monoculture of the area as can be proved by the dust bowl after farming the area for only 50 years. Most people who farmed this area in the late 1800’s failed miserably because the land and climate was not suited for the type of farming employed. The government basically opened this area up to people knowing full well that it was an impossible endeavor, thus destroying the whole area.
Sure, if you stop the history at 1925. Since the 1930s we have had various cycles of rain and drought…this has probably gone on since time immemorial. We are also very good at crop management now. Winter ground coverage, crop rotation, new crops…cotton…even hemp now. Millions of acres have also been returned to range land as they should have been all along. The dirt here is like talcum powder…I’ve seen it blow through plastic bags! Leave it uncovered and it’s a dust storm.
It hasnt helped that Colorado has dammed the Arkansas rendering the region through KS without some of the water.
THip song holds true, 28 years later. Art leads reality.
The plates are moving and causing change. It has been doing so for many years.
Well here it is 2022 fall, and I live in missouri and can attest to the fact we are becoming more arid. We have little in the way of regular rain now. We get storms but they are far and few. This summer was one of the driest and its been getting that way for a while. The trees starting leaf dropping and browning in late july and august. According to the drought monitor we have been under a moderate drought for a year, and thats not normal for where we are. And every year we have some level of drought.
We are heavy forest lakes and rivers we normally have an abundance of rain, but for the last 10 years I have notice a shift in rainfall. It started in 2011,it was around that time we had one of the worst droughts. People were selling off herds cheap because there was no feed for them. The climate in this area is changing to a semi arid one. At the same time the mid country corridor is heating up, you should correlate the two events. They will both be linked.
The title of this article is disingenuous, misleading, and detracts from the studies it references. The Great Plains is not defined by climate & the 100th Meridian is not “Where the Great Plains Begin.” That’s cutesy but inaccurate.
In fact, the study actually states that the 100th Meridian BISECTS the Great Plains & delineates the arid/humid divide. They use it as a reference point to look at climate changes.
I agree with the premise of the studies, however. I’m a retired meteorologist, geologist, & engineer who grew up in North Dakota & now lives in Texas. Many family members are farmers & ranchers throughout the central US. My personal experience (altho anecdotal) shows that the line between wet/dry for our weather & climate has indeed shifted farther east.
I have driven and witnessed the line in Texas in the I10 it would be nice to see some photos of this.